ALBERT

Description: 〈h3〉Abstract〈/h3〉 〈p〉The scarcity of rainfall data is one of the main problems affecting the use of hydrological models. Several model satellite-based rainfall estimates (SREs) have been developed to provide an alternative to poorly or ungauged basins. The aim of this work was to evaluate the suitability of SREs for hydrological modeling using a semi-distributed model in the transboundary basin of Medjerda, shared by Tunisia and Algeria. Two satellite-based rainfall products (PERSIANN-CDR and CHIRPSv2) were first compared to rain gauge observations based on sub-basin and point-to-pixel analysis. The selected SREs products were then used as inputs to simulate discharge at a daily time-step over the 1996–2016 period. The simulated streamflows were compared to data measured at four runoff gauging stations and at the outlet of two dams. It was first shown that both SRE products perform weakly at daily scale but that the CHIRPSv2 product performs better at monthly scale. Second, comparison at sub-basin scale led to a better correlation with rain gauge observations than point-to-pixel analysis. Third, direct sampling can be reliably used to fill gaps in discharge time series by using auxiliary stations highly correlated with the target station. Finally, the CHIPRSv2 daily satellite rainfall product is more efficient and more suitable than the PERSIANN-CDR product for hydrological modeling. Thus, CHIRPSv2 can be used as an alternative or as a complementary source of information to simulate hydrological models in arid and semi-arid regions and can successfully solve the issue of missing rainfall data in transboundary catchments.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This paper presents an evaluation of the Weather Research and Forecasting (WRF) model in simulating wet and dry West African monsoon (WAM) rainfall seasons. Three model experiments with varying selected microphysics (MP), cumulus convection (CU), and planetary boundary layer (PBL) schemes based on previous study were performed. Each of the model combinations is used to run four WAM seasons that consist of two wet (2008 and 2010) and two dry years (2001 and 2011). To investigate the behavior of WAM in the context of wet and dry years, the four seasons were used to compute composites of wet and dry WAM seasons in terms of rainfall amount. The analyses majorly focus on the rainfall composites relative to rainfall from Global Precipitation Climatology Project (GPCP) and Tropical Rainfall Measurement Mission (TRMM) as well as temperature, moisture, and atmospheric circulation fields with respect to NCEP reanalyses. This study documents significant sensitivity in simulation of the West African monsoon to the choices of the MP, CU, and PBL schemes. The simulation with the combination of WRF single moment 5 (WSM5) MP, Yonsei University (YSU) PBL, and new Simplified Arakawa-Schubert CU (WSM5-YSU-nSAS) shows good spatial distribution pattern of rainfall and the dynamics associated with the monsoon. Quantitatively, the combination shows less agreement in distinguishing the selected WAM seasons compared with the Goddard MP, Mellor-Yamada-Janjic PBL, and Betts-Miller-Janjić CU (GD-MYJ-BMJ) and the WSM5, Mellor-Yamada-Nakanishi-Niino 2.5 level and new Tiedtke CU (WSM5-MYNN-nTDK). Also, the dynamical structures of the wet and dry WAM circulation composites are reasonably reproduced in GD-MYJ-BMJ and WSM5-YSU-nSAS. The GD-MYJ-BMJ was able to distinguish between wet and dry years and thus underscores its potential to reproduce climate change signals in future work.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The freeze/thaw process and the surface energy budget of the seasonally frozen ground in the source region of the Yellow River were investigated by using observed soil temperature and moisture and the energy flux from May 12, 2014, to May 11, 2015. Compared with the Maduo site, the starting date of the freezing process was later and the freezing depth was shallower at Maqu site. The maximum frozen depth was about 320 cm at Maduo site and 90 cm at Maqu site. The soil temperature of Maqu site was higher than of Maduo site due to lower latitude and altitude. The soil was the driest under the depth of 40 cm and 80 cm at Maduo and Maqu sites, respectively. The diurnal amplitudes of soil temperature of Maduo site were larger than of Maqu site at four freeze/thaw stages; the amplitudes were the largest in the completely thawed stage (9.19 °C and 4.35 °C) and minimal in the freezing stage (1.23 °C and 0.47 °C). The diurnal amplitudes of soil moisture of Maqu site were greater than of Maduo site at all stages. The net radiation Rn’s seasonal change was hardly influenced by the freeze/thaw process. The mean ground heat flux (G〈sub〉0〈/sub〉) was negative during the freezing and completely frozen stage and positive during the thawing and completely thawed stage. During the completely thawed and frozen stages, the latent heat flux (LE) and sensible heat flux (H) predominated in the surface energy distribution, respectively. Overall, the variations of fluxes were affected by both the monsoon and freeze/thaw process of the soil layer in seasonally frozen region. The freeze/thaw process had a significant effect on the diurnal change of G〈sub〉0〈/sub〉 during the freezing stage. The annual energy closure status of Maduo and Maqu sites was 0.77 and 0.58, respectively. The energy closure status was the highest during the completely thawed stage at Maduo site and during the thawing stage at Maqu site and lowest during the freezing stage among the four stages, due to the snow cover’s impact. Overall, the freeze/thaw process and the high albedo caused by snow cover had effects on the energy closure status.〈/p〉

Description: 〈p〉The presentation of Fig. 4 was incorrect.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The aim of this work was to investigate the microstructure and mechanical properties of 1vol%-Ni-added yttria-stabilized zirconia (YSZ) toughened alumina composites. First, Ni powders were heterogeneously precipitated in an alumina–zirconia powder mixture suspended in water; the prepared specimens were then pressureless sintered at 1550°C/2 h in a 90vol%Ar/10vol% H〈sub〉2〈/sub〉 atmosphere. The structure of phases and microstructure of the composites were characterized by X-ray diffraction and scanning electron microscopy, respectively. Mechanical characterization of the specimens was carried out through Vickers hardness, Vickers indentation toughness, and three-point flexural bending tests. The fine Ni particles were homogeneously dispersed throughout the alumina matrix because of the employed processing method. Furthermore, hardness and toughness values were found to increase by 8% and 50%, respectively, with Ni addition, whereas the relative densities and flexural strength values were found to remain unchanged.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study evaluates the monthly, seasonal, and annual characteristics of near-surface air temperature as a function of both elevation and geographical coordinates over Pakistan, using a climatic data set from 53 observation stations ranging between 5 and 2317 m asl and stepwise multiple regression. Forcing processes for temperature gradient (TG) variation were determined by analyzing its relationship with moisture flux (〈em〉qv〈/em〉) and gradients of rainfall and saturation vapor pressure (〈em〉e〈/em〉〈sub〉s〈/sub〉). The bi-model pattern of TG〈sub〉E〈/sub〉 (temperature gradient with topographic elevation), which earlier studies (TAAC 113(3):671-682, TAAC 132:1129-1141) from the southern slopes of the Himalayas have observed, is also consistent in this study region. However, the forcing strengths, mechanisms, and processes for the monthly variations in TGs magnitude and their diurnal range are somewhat different. The annual cycle of TG〈sub〉E〈/sub〉 in this study is inversely (positively) associated with the rainfall (〈em〉e〈/em〉〈sub〉s〈/sub〉) gradient. Monsoon and orographic controls for TG〈sub〉E〈/sub〉 are stronger in summer, especially in the day, while the influences of inversions and mountainous topoclimate are higher during the non-monsoon period, in particular in winter and at night. Mountain barrier effects are higher in summer, which considerably hamper the relationship between temperature and geographical coordinates and rainfall and elevations. Steeper values of mean TG〈sub〉E〈/sub〉s in the non-monsoon period are the result of strong dry convectional cooling at higher elevations due to high thermal forcing effects at lower elevations. Sensible heating reduction due to westerly-driven precipitation and cloud cover in daytime in the northern mountainous region (or higher latitudes) further strengthens the TG〈sub〉E〈/sub〉 value in this period. This effect is weaker in the surrounding regions; therefore, the TG〈sub〉E〈/sub〉 magnitude in this study is expected to be higher, especially in the pre-monsoon season. Gradients are more shallow in winter (excluding latitude), but values are greater than those in summer, due to distinct variations in moisture and cloud amount, i.e., lower in winter and higher in summer, particularly at lower elevations. Observed distinct differences in TG diurnal range between elevation (high) and latitude (low) in this study are due to a wide variation in temperature, topography, and elevations within the same latitudinal belts. In this study, the lowest gradient values for elevation are observed in August and the highest in May, 1 month later than observed in adjacent mountain regions due to the late arrival of monsoon moisture in summer and intense thermal forcing effects following the wet early pre-monsoon months. Distinct variability of gradient magnitudes between the northern mountainous region and the southern flat terrain is due to differences in topoclimates, moisture amounts, elevations, and geographical coordinates.〈/p〉

Description: 〈p〉The original version of this article unfortunately contained a mistake.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Land surface temperature (LST) plays a key role in the surface energy budget computation and land surface process studies. The Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard the Aqua and Terra satellites provide comprehensive global LST estimates at a fine spatial resolution. The MODIS products were recently upgraded to Collection 6, and shown to be more accurate than its predecessor Collection 5 products. In this study, LST and its variability have been examined across India from Collection 6 of the Aqua MODIS data at 0.05° spatial resolution for the period of 2003 to 2017. All-India mean LST characteristics show distinctive features as compared to the well-documented mean characteristics of near-surface air temperature. All land cover types except permanent snow and ice, and cold desert areas exhibit bimodal peaks in seasonal variations of daytime LST. The daytime LST over the coldest and high-altitude regions of northern India shows anomalous positive linear relationship with NDVI at a monthly scale. However, monthly domain-mean daytime LST of cropland regions is largely negatively correlated with NDVI as compared to other land cover types. Results reveal that about 17% of the Indian landmass received its hottest LST during 2010 followed by 2016. Linear trend analysis for the 15-year period of mean annual LST shows a decrease in diurnal temperature range over most parts of the country due to rather rapid increase in nighttime LST than daytime LST, similar as changes in near-surface air temperature across the country.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study presents the first comprehensive evaluation of the performance of the monthly TRMM rainfall product (3B43-v7) in capturing the rainfall patterns, on the geographic area of the central Mediterranean during the period 1998–2017. Monthly rainfall data from a network of ground-based stations were used to compute a series of spatiotemporal evaluation statistics for the satellite measurement accuracy. These statistics showed a satisfactory accuracy of the examined satellite products in capturing seasonal and annual rainfall patterns, having rather high correlation coefficients (0.75 to 0.96). Nevertheless, a slight 〈em〉overestimation〈/em〉 of the rainfall values (with a mean value lower than 15 mm) implied by the TRMM was found at seasonal basis with the exception of 〈em〉winter〈/em〉 when a small 〈em〉underestimation〈/em〉 (with a mean value amounting to 8 mm) was detected. The 〈em〉overestimation〈/em〉 tendency was mainly detected over the northern and the western parts of the studied domain, where the effect of the earth surface altitude seems to be important. An 〈em〉underestimation〈/em〉 tendency prevails over the marine regions and seems to be associated with the rain rate (in the sense that heavy rainfall episodes are underestimated more). The overall biases of the TRMM rainfall product in respect to the control ground-based station sample found to be within ± 0.2 of the local rainfall standard deviation and nonstatistically significant almost in half of the cases in all seasons except winter. The possible causes of the detected diversity of the seasonal error statistics behavior were further explored and discussed.〈/p〉

Description: 〈p〉Figures 3 and 4 were the same.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉A suite of Regional Climate Model (RegCM) experiments are performed over south Asia to examine the skill of RegCM to simulate the seasonal and sub-seasonal mean features of Indian summer monsoon (ISM). Because of coupled nature of ISM, three model experiments with RegCM are conducted to examine the skill of coupled and uncoupled configurations of RegCM by forcing it with observed SST (Exp1), coupling it to a simple slab ocean model (SOM) with constant mixed layer depth (MLD; Exp2) and with climatology of MLD (Exp3). The coupled experiments show an overall improvement in several aspects of ISM variability at seasonal and intraseasonal time-scales, despite bias in simulated SSTs. Between coupled experiments; Exp3 reduces biases in SST distribution over the region to the north of Arabian Peninsula, eastern Arabian Sea (AS), and broadly over north Indian Ocean (NIO). Noteworthy is the improved precipitation over central India (CI), head Bay of Bengal (BoB), as well as the representation of easterly wind shear in coupled experiments. At intraseasonal time scales, Exp3 produces spectral peaks above red noise at 25–50-day and 15–20-day periods closely representing the northward propagating intraseasonal mode and quasi-biweekly oscillating mode as in observed precipitation. The improved representation of spatial distribution of intraseasonal activity over NIO as well as the SST and precipitation relationships over head BoB and eastern AS is attributed to better representation of air-sea interaction in Exp3. In brief, the coupling improves the model skill for the true representation of mean ISM variability during boreal summer, and the thorough evaluation of model for longer periods is required to employ it as a downscaling tool for regional climate change studies.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Spatiotemporal changes of temperature and precipitation extremes from 1956 to 2015 were analyzed at 200 representative weather stations evenly distributed in the temperate continental zone (TCZ), temperate monsoon zone (TMZ), mountain plateau zone (MPZ), and (sub) tropical monsoon zone (SMZ) of China, using 16 extreme temperature and 11 extreme precipitation indexes. The results showed that warm days (TX90p) and warm nights (TN90p) increased significantly, while cool days (TX10p) and cool nights (TN10p) decreased significantly in the whole China. Overall increasing trends were found for maximum and minimum daily maximum temperature (TXx and TXn) and maximum and minimum daily minimum temperature (TNx and TNn). Warm indexes, including summer days (SU25), tropical nights (TR20), warm spell duration indicator (WSDI), and growing season length (GSL), showed increasing trends, whereas cold indexes such as frost days (FD0), ice days (ID0), cold spell duration indicator (CSDI), and diurnal temperature range (DTR) showed decreasing trends. These extreme temperature indexes exhibited high correlations with mean air temperature. MPZ exhibited the most remarkable change magnitudes among the four zones, while the smallest changes occurred in SMZ. An accelerating warming trend was particularly observed since 1986. Nationally, only daily rainfall intensity (SDII) showed significantly increasing trends, while the increasing trends of other precipitation indexes were not significant. Apart from consecutive wet days (CWD), changes of precipitation extremes presented increasing trends. PRCPTOT and R10mm exhibited the highest correlation coefficient across contrasting climatic zones. Regionally averaged precipitation totals were decreasing in TMZ during 1956–1985, but increasing trends were identified after 1985. The upward tendency of precipitation totals in MPZ and the west part of TCZ may alleviate the pressure of water shortage in arid and semi-arid regions of China, but the upward trend in SMZ, especially in the coastal areas of southeastern China, may aggravate the risk of flood-induced disasters in these regions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉To understand the formation and growth mechanism of the magnetite phase during the fluidized reduction of hematite, a high-purity hematite ore was isothermally reduced using a 20vol% CO?80vol% CO〈sub〉2〈/sub〉 gas mixture in a micro-fluidized bed to examine the process of the selective conversion of hematite to magnetite. The micro-structural characteristics of the magnetite phase were investigated using scanning electron microscopy (SEM) and the Brunauer, Emmett, and Teller (BET) method, and the thickness of the magnetite layer was measured and evaluated using statistical analysis. The experimental results showed that the fresh magnetite nuclei were dense needles of different lengths, and the original hematite grains became porous after complete reduction to the magnetite phase. The thickness of the magnetite layer increased with an increase in reduction temperature and reduction time. The growth kinetics of the magnetite layer was investigated, and the value of the activation energy 〈em〉E〈/em〉 was estimated to be 28.33 kJ/mol.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The separation of andalusite and quartz was investigated in the sodium oleate flotation system, and its mechanism was studied by solution chemical calculation, zeta-potential tests, Fourier transform infrared spectroscopic (FTIR), and X-ray photoelectron spectroscopic (XPS). The flotation tests results show that FeCl〈sub〉3〈/sub〉·6H〈sub〉2〈/sub〉O has a strong activation effect on andalusite and quartz and citric acid has a strong inhibitory effect on activated quartz, thus increasing the floatability difference between quartz and andalusite when the pulp pH is approximately 8. The FTIR, Zeta potential, and XPS analyses combined with the chemical calculation of flotation reagent solutions demonstrate that Fe forms hydroxide precipitates on the surface of andalusite and quartz and that oleate anions and metal ions adsorb onto the surface of the minerals. The elements Al and Fe can be chemically reacted. The anions in citric acid have different degrees of dissolution of Fe on the andalusite and quartz surfaces, thereby selectively eliminating the activation of the elemental Fe on andalusite and quartz and increasing the floatability of andalusite, leading to a better separation effect between andalusite and quartz.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉To inhibit the dissolution of Mg〈sup〉2+〈/sup〉 during the bioleaching process of high-magnesium nickel sulfide ore, the effect of major bi-oleaching factors on the dissolution of Mg〈sup〉2+〈/sup〉 from olivine and serpentine was investigated and kinetics studies were carried out. The results indicated that the dissolution rate-controlling steps are chemical reaction for olivine and internal diffusion for serpentine. The most influential factor on the dissolution of Mg〈sup〉2+〈/sup〉 from olivine and serpentine was temperature, followed by pH and particle size. A novel method of bi-oleaching at elevated pH was used in the bioleaching of Jinchuan ore. The results showed that elevated pH could significantly reduce the dissolution of Mg〈sup〉2+〈/sup〉 and acid consumption along with slightly influencing the leaching efficiencies of nickel and cobalt. A model was used to explain the leaching behaviors of high-magnesium nickel sulfide ore in different bioleaching systems. The model suggested that olivine will be depleted eventually, whereas serpentine will remain because of the difference in the rate-controlling steps. Bioleaching at elevated pH is a suitable method for treating high-magnesium nickel sulfide ores.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The objective of this work is to investigate the interaction between the climate indices precipitation concentration degree (PCD), precipitation concentration period (PCP), and oceanic patterns associated with drought disasters in the Northeast of Brazil (NEB). The average values of drought disasters were situated at the semi-arid zone, while the hotspots between 95 and 99% of significance were more centralized, particularly in the states of Ceará, Rio Grande do Norte, Paraíba, and Pernambuco, where significant areas were located. The PCD patterns showed that precipitation was concentrated in the north of this region and the wettest quarter happened from February to April, in accordance with PCP patterns. The analysis of variance (ANOVA) A showed evidence of the variability of PDC and PCP in relation to the well-known variability modes of the oceans. However, only two areas of NEB presented statistical significance.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Based on daily mean temperature data from 32 meteorological stations in the Qinling Mountains (QMs) of China, we analyzed the characteristics and differences of the spatiotemporal changes in the climatic growing season (CGS) in the QMs from 1964 to 2015. Our results are as follows. First, over the past 52 years, the temperature of the QMs significantly increased at a mean rate of 0.22 °C/decade (〈em〉P〈/em〉 〈 0.01) in over 98.04% of the area. Significant north–south spatial differences were observed in temperature changes; also, significant differences in the temperature changing trends were observed before and after the abrupt change in temperature. Second, the spatial distributions of the mean growing season start (GSS), end (GSE), and length (GSL) in the QMs varied based on regional differences in latitude and topography. Notably, the GSS, GSE, and GSL were gradually delayed, advanced, and shortened, respectively, as latitude and elevation increased. After the abrupt change in temperature, whether it is in the NSQM (northern slopes of the QMs) or the SSQM (southern slopes of the QMs), the GSS, GSE, and GSL expanded into high-elevation areas. Third, over the past 52 years, the GSS in the QMs exhibited a significant advancing trend of 2.7 days/decade, the GSE was delayed at a rate of 0.66 days/decade, and the GSL displayed a significant extension of 3.36 days/decade. Before the abrupt change in temperature, the GSS, GSE, and GSL exhibited non-significant changing trends; however, the trends in the GSS, GSE, and GSL were more significant after the abrupt change than before. Fourth, the GSS, GSE, and GSL trends in the QMs were significantly different in the NSQM and SSQM regions. After the abrupt change, the GSS, GSE, and GSL trends along the NSQM were more significant than those along the SSQM.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This paper reports a study on the reconstruction of broken Si-O-Si bonds in iron ore tailings (IOTs) in concrete. Limestone and IOTs were used to investigate the influence of different types of coarse aggregates on the compressive strengths of concrete samples. The differences in interfacial transition zones (ITZs) between aggregate and paste were analyzed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Meanwhile, X-ray diffraction (XRD) and infrared spectroscopy (IR) were used to study microscopic changes in limestone and IOTs powders in a simple alkaline environment that simulated cement. The results show that the compressive strengths of IOTs concrete or paste are higher than those of limestone concrete or paste under identical conditions. The Ca/Si atom ratios in the ITZs of IOTs concrete samples are lower than those of limestone concrete; the diffraction peak of the calcium silicate phase at 2〈em〉θ〈/em〉 = 29.5°, as well as the bands of Si-O bonds shifting to lower wavenumbers, indicates reconstruction of the broken Si-O-Si bonds on the surfaces of IOTs with Ca(OH)〈sub〉2〈/sub〉.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉An environmentally friendly organic biosorbent was fabricated using hay by succinylation. Metallic cation adsorption tests were performed using synthetic nickel(II) and cadmium(II) solutions to simulate heavy-metal recovery from aqueous solution. The adsorption efficiency was greater than 98% for both cadmium and nickel ions when the biosorbent concentration was 5.0 g/L and the initial metal concentrations were 50 mg/L. The surface of the biosorbent was characterized using Fourier transform infrared spectroscopy to investigate the changes in the surface functional groups. The functional groups changed according to the surface treatment, resulting in an effective biosorbent. The kinetics of the metals adsorption revealed that the reactions are pseudo-second order, and the adsorption isotherm well followed the Langmuir model. The maximum adsorption capacities predicted by the Langmuir model were 75.19 mg/g and 57.77 mg/g for cadmium and nickel, respectively. The fabricated biosorbent was regenerated using NaCl multiple times, with 2.1% for Cd and 4.0% for Ni in adsorption capacity after three regeneration cycles. The proposed biosorbent can be a good alternative to resin or other chemical adsorbents for heavy-metal recovery in metallurgical processing or municipal water treatment.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this work, the microstructure and the strain partitioning of lean duplex stainless steel 2101 (LDX 2101) during different hot-rolling processes are investigated by optical microscopy and electron-backscattered diffraction (EBSD). The results show that the LDX 2101 exhibits poor thermoplasticity at high temperature. The four-pass hot-rolled plates show fewer edge-cracking defects and superior thermoplasticity compared with the two-pass hot-rolled plates prepared at different temperature. The phase boundary is the weakest site in the LDX 2101. The cracks are initiated and propagated along the phase boundaries during the hot-rolling process. According to the EBSD analysis, the increase of the hot-rolling pass can dramatically improve the strain distribution in ferrite and austenite phases and promote the strain transmission in the constituent phases, thereby improving the coordinated deformation ability of the two phases. This effect further increases the thermoplasticity and reduces the formation of edge cracks in LDX 2101.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this study, antimony production from a stibnite concentrate (Sb〈sub〉2〈/sub〉S〈sub〉3〈/sub〉) was performed in one step using a molten salt electrolysis method and borax as an electrolyte. Electrochemical reduction of the stibnite concentrate was performed at 800°C under galvanostatic conditions and explained in detail by the reactions and intermediate compounds formed in the borax. The effects of current density (100–800 mA·cm〈sup〉−2〈/sup〉) and electrolysis time (10–40 min) on cathodic current efficiency and antimony yields were systematically investigated. During the highest current efficiency, which was obtained at 600 mA·cm〈sup〉−2〈/sup〉, direct metal production was possible with 62% cathodic current efficiency and approximately 6 kWh/kg energy consumption. At the end of the 40-min electrolysis duration at 600 mA·cm〈sup〉−2〈/sup〉 current density, antimony reduction reached 30.7 g and 99% of the antimony fed to the cell was obtained as metal.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Joining Mg to Al is challenging because of the deterioration of mechanical properties caused by the formation of intermetallic compounds (IMCs) at the Mg/Al interface. This study aims to improve the mechanical properties of welded samples by preventing the fracture location at the Mg/Al interface. Friction stir welding was performed to join Mg to Al at different rotational and travel speeds. The micro structure of the welded samples showed the IMCs layers containing Al〈sub〉12〈/sub〉Mg〈sub〉17〈/sub〉 (γ) and Al〈sub〉3〈/sub〉Mg〈sub〉2〈/sub〉 (β) at the welding zone with a thickness (〉 3.5 〈m). Mechanical properties were mainly affected by the thickness of the IMCs, which was governed by welding parameters. The highest tensile strength was obtained at 600 r/min and 40 mm/rnin with a welding efficiency of 80%. The specimens could fracture along the boundary at the thermo-mechanically affected zone in the Mg side of the welded joint.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉For a long time, coalbed gas has brought about various problems to the safety of coal mine production. In addition, the mining of gas and coalbed methane (CBM) has attracted much attention. The occurrence and migration of CBM are believed to be closely related to the micro-surface properties of coal. To further explore the characteristics of CBM occurrence and migration, in this study, the micro-surface topography, adhesion, and elastic modulus of five metamorphic coals were measured by atomic force microscopy (AFM). The results show that the microtopography of coal fluctuates around 40 nm, reaching a maximum of 66.5 nm and the roughness of the surface decreases with the increase of metamorphism. The elastic modulus of coal micro-surface varies from 95.40 to 9626.41 MPa, while the adhesion varies from 15.08 to 436.22 nN, and they both exhibit a trend of “M” shape with the increase of metamorphism. Furthermore, a high correlation exists between adhesion and microtopography fluctuation. In most cases, the adhesion is larger in the concavity area and smaller in the convexity area. The research results may provide a new method for revealing the occurrence and migration of CBM and ensure efficient and safe CBM exploitation.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This paper reports a piezoelectric nanogenerator (NG) with a thickness of approximately 80 μm for miniaturized self-powered acceleration sensors. To deposit the piezoelectric zinc oxide (ZnO) thin film, a magnetron sputtering machine was used. Polymethyl methacrylate (PMMA) and aluminum-doped zinc oxide (AZO) were used as the insulating layer and the top electrode of the NG, respectively. The experimental results show that the ZnO thin films annealed at 150°C exhibited the highest crystallinity among the prepared films and an optical band gap of 3.24 eV. The NG fabricated with an AZO/PMMA/ZnO/stainless steel configuration exhibited a higher output voltage than the device with an AZO/ZnO/PMMA/stainless steel configuration. In addition, the annealing temperature affected the open-circuit voltage of the NGs; the output voltage reached 3.81 V when the annealing temperature was 150°C. The open-circuit voltage of the prepared self-powered accelerometer increased linearly with acceleration. In addition, the small NG-based accelerometer, which exhibited excellent fatigue resistance, can be used for acceleration measurements of small and lightweight devices.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The stabilization of severely As-polluted soil has been a challenge, especially for the extremely toxic As(III) contaminants. In this study, soil with a high As concentration (26084 mg/kg) was availably stabilized by a H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 pre-oxidation assisted TMT-15 (Na〈sub〉3〈/sub〉S〈sub〉3〈/sub〉C〈sub〉3〈/sub〉N〈sub〉3〈/sub〉 solution with a mass fraction of 15%) and FeCl〈sub〉3〈/sub〉·6H〈sub〉2〈/sub〉O stabilization method. The results showed that the combination of the two stabilizers (i.e., TMT-15 and FeCl〈sub〉3〈/sub〉·6H〈sub〉2〈/sub〉O) presented a better stabilization behavior than either stabilizer used individually. The use of the H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 pre-oxidation assisted TMT-15 and FeCl〈sub〉3〈/sub〉·6H〈sub〉2〈/sub〉O stabilization approach not only converted the As(III) to As(V) but also reduced the toxic leaching concentration of As to 1.61 mg/L, which is a safe level, when the additions of TMT-15 and FeCl〈sub〉3〈/sub〉·6H〈sub〉2〈/sub〉O were 2 mL and 0.20 g, respectively. Thus, using only a simple H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 pre-oxidation to combine clean stabilization with non-toxic stabilizers TMT-15 and FeCl〈sub〉3〈/sub〉·6H〈sub〉2〈/sub〉O could render the severely As-contaminated soil safe for disposal in a landfill.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Monsoon rainfall exhibits the prominent diurnal variability. It is essential to capture the diurnal behaviour of the rainfall on the spatiotemporal scale by mesoscale models for its accurate prediction. The present study appraises the diurnal variability of simulated rainfall by Weather Research and Forecasting (WRF) model over the South Asian region during Indian summer monsoon seasons of the years 2008–2012. For examining the amplitude, phase, and variance of the simulated diurnal cycle of rainfall, harmonic analysis of model outputs are carried out and compared it with that of TRMM rainfall estimates to quantify errors. The model is overall successful in simulating the pattern of diurnal variation of rainfall, but underestimates its amplitude compared to the observed one especially over the western Himalayas, northeast India, central India, and the north Bay of Bengal (BoB). However, the amplitudes of the diurnal variation match well over south BoB. The simulated phases of the diurnal cycle either leads (over central India and NW India by 3 h) or lags (over the sub-Himalayan region by 12 h) than the observed phase angle. The simulated time of maximum rainfall matches over south Peninsula, while over the west coast, neither observation nor forecast shows pronounced diurnal cycle. The north BoB shows morning maxima in rainfall in both observation and forecast; however, over south BoB, the time of maximum simulated rainfall leads by 3 h. Even though the model is overall successful in representing the diurnal variation of rainfall, it requires improvement for proper representation of phase and sub-diurnal variation appropriately.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The bulk transfer method is commonly used to calculate the surface sensible heat (SSH) flux in climatology and in the numerical model, but in the calculation, the value of the bulk transfer coefficient for heat (〈em〉C〈/em〉〈sub〉〈em〉h〈/em〉〈/sub〉) is generally regarded as a fixed value (e.g., 0.004 in the Tibetan Plateau), without considering its seasonal variations and regional differences. In this study, a new method for upscaling data from the local to regional scale is proposed and tested to estimate 〈em〉C〈/em〉〈sub〉〈em〉h〈/em〉〈/sub〉 over the east-central Tibetan Plateau (TP) using the latest version Global Inventory Modeling and Mapping Studies (GIMMS), Normalized Difference Vegetation Index (NDVI) dataset, and micrometeorological observations collected at four field sites. Results suggest that the proposed method is capable of reflecting the variations in 〈em〉C〈/em〉〈sub〉〈em〉h〈/em〉〈/sub〉 at the regional scale in a climatic context. It is a relatively reliable way of estimating the value of 〈em〉C〈/em〉〈sub〉〈em〉h〈/em〉〈/sub〉 using satellite remote sensing data and field observations. Then, the monthly values of 〈em〉C〈/em〉〈sub〉〈em〉h〈/em〉〈/sub〉 and the SSH flux at 70 China Meteorological Administration (CMA) stations on the east-central TP during the period 1982–2012 are estimated. Results show that the value of 〈em〉C〈/em〉〈sub〉〈em〉h〈/em〉〈/sub〉 ranges from 0.0025–0.0050, with obvious seasonal variations and spatial differences. Because the surface vegetation coverage in the southeastern part of the TP is better than that in the north-central part, the values of 〈em〉C〈/em〉〈sub〉〈em〉h〈/em〉〈/sub〉 are higher than that in the north-central part of the TP throughout the year. The SSH flux also shows obvious seasonal variations and spatial differences, which is strongest in spring, followed by summer and autumn, and smallest in winter. Furthermore, the seasonal mean SSH has undergone a significant interdecadal transition in the early 2000s, from the previous weakening trend to the strengthening trend. Based on the results of this study, the values of 〈em〉C〈/em〉〈sub〉〈em〉h〈/em〉〈/sub〉 obtained from a limited number of local field observations on the plateau can be applied to more CMA stations at the regional scale. Such a method can improve the calculation accuracy of the SSH flux over the TP and aid studies of plateau meteorology and climatology.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study investigates the potential impacts of climate change on wind power over West Africa under various global warming levels. For the study, we analysed eleven multi-model multi-ensemble simulation datasets from the Coordinated Regional Climate Downscaling Experiment (CORDEX) project. The model simulations for the present-day climate were compared with available station observation data and two examples of reanalysis data (ERA-INTERIM and ERA-20C). The results show that model ensemble mean gives a realistic simulation of wind speed and wind power density (WPD) over West Africa, although it overestimates them. In agreement with the reanalysis, the models indicate that the strongest winds and largest WPD are in the Sahel zone, especially around Dakar. However, while the regional climate models (RCMs) show thirteen cities are viable for potential wind power generation in the historical climate, the reanalysis indicates only four Sahelian cities are suitable for it. The RCMs project an increase in monsoon wind speed and WPD over West African cities and the magnitude of the increase grows with the global warming levels. Nevertheless, the increase is not sufficient to make the cities in the Guinean and Savannah zones viable for wind power generation in the warmer climate. The results of the study may guide policymakers on harnessing wind power potential to meet the electricity demands of West Africa in the future.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Land surface air temperature (SAT) change is one of the core issues in monitoring and assessing regional climate change. In this study, the characteristics of SAT change over DPR Korea for the period 1918–2015 were investigated using a high-quality historical dataset. Results show that the region-averaged annual mean SAT increased 0.21 °C/decade for the period 1918–2015 on the basis of data from four stations and 0.19 °C/decade for the period 1941–2015 as estimated based on data from nine stations. Before the 1970s, Pyongyang station in the central region experienced the largest warming trend. Linear trends of seasonal mean SAT during 1941–1970 were negative for all seasons in eastern coast and for summer and autumn in western coast and northern inland areas. Since 1971, however, the annual and seasonal mean SAT trends have shifted to positive values in all regions, with winter experiencing the most rapid warming. During the period of global warming slowdown since 1998 or 2000, no significant seasonal warming trend of wintertime was detectable, and this caused the smallest winter warming for the last 45 years. Other seasons also witnessed a generally weakened warming during 1971–2015 compared to that of 1971–2000. The results of the study will help in understanding regional climate change and in assessing the impacts of climate change on economic and natural ecosystems in the country.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study attempts to make comparison between different parametric regressive models for the bivariate binary data with a machine learning technique. The data on sequential occurrence of rainfall in consecutive days is considered. The outcomes are classified as rainfall in both days, rainfall in one of the consecutive days, and no rainfall in both days. The occurrence of rainfall in consecutive days is analyzed by using statistical models with covariate dependence and classification tree for the period from 1980 to 2014. We have used relative humidity, minimum temperature, maximum temperature, sea level pressure, sunshine hour, and cloud cover in the model as covariates. The binary outcome variable is defined as the occurrence or non-occurrence of rainfall. Five regions of Bangladesh are considered in this study and one station from each region is selected on the basis of two criteria: (i) contains fewer missing values and (ii) representative of the regional characteristics geographically. Several measures are used to compare the models based on Markov chain and classification tree. It is found that for yearly data, both the Markov model and classification tree performed satisfactorily. However, the seasonal data show variation of rainfall. In some seasons, both models perform equally good such as monsoon, pre-monsoon, and post-monsoon, but in the winter season, the Markov model works poorly whereas classification tree fails to work. Additionally, we also observe that the Markov model performed consistently for each season and performs better compared with the classification tree. It has been demonstrated that the covariate-dependent Markov models can be used as classifiers alternative to the classification tree. It is revealed that the predictive ability of the covariate-dependent Markov model based on Markovian assumption performs either better or equally good compared with the classification tree. The joint models also consistently showed better predictive performance compared with regressive model for whole year data as well as for several seasonal data.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The rapid development of cities has led to the urban sprawl to the suburbs. Studies have shown that urban sprawl leads to the increasing intensity of heat island effect. This paper, based on the DMSP/OLS nighttime light data and the MODIS land surface temperature data during the years 2000, 2005, and 2013, discussed the spatial and temporal characteristics of urban sprawl, urban heat island intensity in China, and their relationship, respectively. The results show that (1) the national urban expansion index showed an upward trend. The urban area was 104,000 km〈sup〉2〈/sup〉 in 2000, 169,000 km〈sup〉2〈/sup〉 in 2005, and 312,000 km〈sup〉2〈/sup〉 in 2013.The average annual growth rate was 10.2% in 2000–2005, 8% in 2000–2013, and 8.8% in 2000–2013. (2) The national heat island index also showed an upward trend; total heat island intensity was 716.73 °C in 2000, 812.84 °C in 2005, and 995.46 °C in 2013. The annual average growth rate was 2.55% in 2000–2005, 2.57% in 2005–2013, and 2.56% in 2000–2013. (3) There is a positive correlation between urban spatial expansion and heat island intensity in China. The urban and suburban range of China can be objectively extracted from the DMSP/OLS nighttime light data every year and superimposed with the MODIS land surface temperature data of the same period, which ensures the correctness of the urban heat island intensity based on the actual changes of suburban areas and main urban areas in each city, and overcomes the calculation error of the traditional method, which neglects that some suburbs have become urban areas and are still regarded as suburbs. These results provide spatiotemporal changes characterization of urban area in China during recent decades, which are helpful in decision-making of land management and planning for sustainable development.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Storm is a convective cell much smaller than a mesoscale convective system (MCS) but typically larger than a cumulonimbus cloud and heavy precipitation and lightning are often associated with it. Storms contribute major fraction of the convective precipitation in MCSs. Storm characteristics and precipitation estimates around New Delhi (28.6°N, 77.2°E; an Indian land location) during June–September period of the year 2013 are reported here using data of C-band polarimetric Doppler weather radar. Storms, defined based on radar reflectivity thresholds (30 dBZ for simple storms and 40 dBZ for intense storms), are tracked and their properties are extracted. Our results show that about 80% of storms exist for 1 h or less. The areas of 90% of simple storms are less than 100 km〈sup〉2〈/sup〉 and the largest area averaged over storm lifespan does not exceed 400 km〈sup〉2〈/sup〉. The majority of storms (〉 80%) move with speeds less than 30 km h〈sup〉−1〈/sup〉. About 60–65% of simple/intense storms have echo top heights between 6 and 10 km, while only few of them exceed 17 km. The values of average thickness of simple and intense storms lie between ~ 2–10 and ~ 1–7 km, respectively. It is not the vertical extent of a storm but its area-time integral that correlates better with the total precipitation amount. Around the New Delhi area, daily accumulated precipitation derived from relations incorporating polarimetric variables is in good agreement with the rain gauge measurements while that obtained from relations based on radar reflectivity factor (Z〈sub〉〈em〉h〈/em〉〈/sub〉) alone highly underestimates precipitation. This suggests that polarimetric capability is needed in Doppler weather radars to get the realistic precipitation estimates. The mean precipitation water content derived from Z〈sub〉〈em〉h〈/em〉〈/sub〉 (~ 0.96 g m〈sup〉−3〈/sup〉) is about 30–40% less compared to that derived from polarimetric relations. Our findings on storm properties have implications for cloud parameterizations and in short-term weather forecasting.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Experimental beneficiation processes of quartz concentrate in arc plasma torches of two different types and electric powers were studied. An emission scanning electron microscope and a universal laser analyzer were used to investigate the structures as well as the size distributions of grains and microparticles. Inductively coupled plasma-mass spectrometry was used to determine the chemical compositions of nonstructural solid-phase mineral impurities in quartz concentrate. Results related to the modified grains’ structure and size distribution, the compositions of impurities, and the gas-liquid inclusions in the quartz concentrate were investigated. The total impurities concentrations in the processed grains were found to satisfy the IOTA-STD standard (industry standard for grading high quality fused quartz products). The optimal condition (i.e., the optimal specific plasma enthalpy) for the production of high-purity quartz in arc plasma torches was found to depend on the geological-genetic type and the structural and textural features (i.e., chemical composition and gas-liquid inclusions) of the quartz concentrate.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The evolution of mean annual minimum (TMIN) and maximum temperature (TMAX) on the Swiss Plateau shows distinct differences over the last 150 years. TMIN increased relatively steadily by about 3 °C. TMAX increased by only 1.5 °C with substantial decadal variability and hardly any increase until about 1940. However, in the most recent decades, TMAX trends are somewhat larger than TMIN trends. While most aspects of the TMIN evolution can be well explained by the global forcing and the modifying effects of the large-scale atmospheric flow alone, local sunshine duration (SD) information is crucial to explain major features of the TMAX series and the differences between TMIN and TMAX since about 1950. SD shows no clear trend until 1950, a decline from 1950 to 1980 and an increase since 1980 resembling the global dimming and brightening signal. TMAX is strongly influenced by SD and the TMAX evolution can be well reconstructed with local TMIN and SD. Strong TMAX declines are found from 1950 to the 1970s. TMIN shows no trend in this period. Between 1980 and about 2005, both TMIN and TMAX show strong increases caused by the greenhouse gas forcing, decreasing aerosols and probably also decreasing cloud cover. Since about 2005, the increases are weaker. The brightening has weakened and the warming effect of the continuously growing greenhouse gas forcing has additionally been reduced by cooling effects caused by large-scale atmospheric flow anomalies. The reasons for the considerable differences in the TMIN and TMAX evolution prior to 1950 remain unknown and further investigations are needed to shed more light on this disparity.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The goal of the present study is to improve the elevated temperature wear resistance of an Al−17wt%Si−5wt%Cu alloy (AR alloy) by a novel short duration heat treatment process. The elevated temperature (100°C) dry sliding wear behavior of an AR alloy was studied after microstructural modification using the proposed heat treatment. The study revealed considerable microstructural modifications after the heat treatment and the heat treated alloy was designated as HT (heat treatment) alloy. A higher hardness value was obtained for the HT alloy compared to the AR alloy. Accordingly, the wear rate for the HT alloy was found to be significantly lower compared to the as-cast AR alloy at all applied loads. Accelerated particle pull-out for the AR alloy at elevated temperatures resulted in poor wear behavior for it compared to the HT alloy. On the other hand, the Si particles remained intact on the worn surface of the HT alloy due to the good particle/matrix bonding that resulted from the isothermal heat treatment. Furthermore, the age hardening that occurred in the HT alloy during wear provided additional wear resistance. Thus, the HT alloy at 100°C exhibited a lower wear rate compared to the AR alloy even at room temperature for all applied loads. This improvement was attributed to microstructural modification upon isothermal heat treatment along with the age hardening effect.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The feasibility of aluminum recovery from secondary aluminum dross by extraction with NaOH solution and the subsequent synthesis of MgAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 spinel by sintering the extracted slag were studied. The extraction percentage of soluble aluminum from the dross reached 80% at a temperature of 353 K, liquid-to-solid ratio of 12 mL·g〈sup〉−1〈/sup〉, stirring speed of 300 r·min〈sup〉−1〈/sup〉, and an extraction time of 15 min; the hydrolysis percentage of AlN reached 40% with an extraction time of 30 min. The activation energies of the soluble aluminum and AlN extracted from the dross were 7.15 and 8.98 kJ·mol〈sup〉−1〈/sup〉, respectively, indicating that their kinetics were controlled by outer diffusion without a product layer. The extracted slag was sintered in the temperature range 1373–1773 K; MgAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 spinel with a compressive strength as high as 69.4 MPa was produced in the sample sintered at 1673 K for 3 h. This value exceeds the threshold (40 MPa) prescribed by the National Standard for the Magnesia and Magnesia−alumina Refractory Bricks of China (GB/T 2275–2007). These results establish the effectiveness of aluminum recovery from secondary aluminum dross and subsequent MgAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 spinel synthesis.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In the present study, the temperature data of 125 stations (1941 to 2012) over parts of India have been analysed to evaluate trends and homogeneity using various statistical tests. The annual average, maximum, and minimum temperature data showed a positive trend of 0.44 °C/100 years, 0.51 °C/100 years, and 0.19 °C/100 years, respectively. All the seasonal temperature variables exhibited a positive trend with exception of the minimum temperature of the monsoon season which showed the negative trend at the rate of 0.05 °C/100 years. The maximum temperature of monsoon season depicted a maximum increase at the rate of 0.80 °C/100 years. The results indicated that the process of urbanisation impacted over the change in temperatures. The homogeneity analysis showed the break years at 1972, 1974, and 1977 for annual average, maximum, and minimum temperatures, respectively, for entire India. The seasonal analysis exhibited that the minimum temperatures of both winter and monsoon seasons and the maximum temperature of the post-monsoon season were homogeneous in nature. The rate of change in magnitude for all annual and seasonal temperature variables showed a considerable increase after the break years.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Recent advances in variable-resolution (VR) global models provide the tools necessary to investigate local and global impacts of land cover by embedding a high-resolution grid over areas of interest in a seamless and computationally efficient manner. We used two eddy covariance tower clusters in the Eastern USA to evaluate surface energy fluxes (latent heat, λ〈em〉E〈/em〉; sensible heat, 〈em〉H〈/em〉; net radiation, 〈em〉R〈/em〉〈sub〉n〈/sub〉; and ground heat, 〈em〉G〈/em〉) and surface properties (aerodynamic resistance to heat transfer, 〈em〉r〈/em〉〈sub〉aero〈/sub〉; Bowen ratio, 〈em〉β〈/em〉; and albedo, 〈em〉α〈/em〉) by uncoupled point simulations of the land-only Community Land Model (PTCLM4.5) and two coupled land–atmosphere Community Earth System Model (CESM1.3) simulations. The CESM simulations included a 1° uniform grid global simulation and global 1° simulation with a 0.25° refined VR grid over the Eastern USA. Tower clusters included the following plant functional types—broadleaf deciduous temperate (hardwood) forest, C3 non-Arctic grass (grass), a cropland, and needleleaf evergreen temperate (pine) forest. During the growing season, diurnal cycles of λ〈em〉E〈/em〉 and 〈em〉H〈/em〉 for grass and the cropland were simulated well by PTCLM4.5 and VR-CESM1.3; however, λ〈em〉E〈/em〉 (〈em〉H〈/em〉) was biased low (high) at the hardwood and pine forested sites, contributing to biases in 〈em〉β.〈/em〉 Growing season 〈em〉R〈/em〉〈sub〉n〈/sub〉 was generally well simulated by CLM4.5 and VR-CESM1.3; however, modeled elevated albedo (indicative of snow cover) persisted longer in winter and spring leading to large biases in 〈em〉R〈/em〉〈sub〉n〈/sub〉 and 〈em〉α〈/em〉. The introduction of a VR grid does not adversely impact surface energy fluxes compared to 1° uniform grids and highlights the usefulness of this approach for future efforts to predict land–atmosphere fluxes across heterogeneous landscapes.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉When long time series are analyzed, two nearby periods may show significantly different trends, which is known as trend turning. Trend turning is common in climate time series and crucial when climate change is investigated. However, the available detection methods for climate trend turnings are relatively few, especially for the methods which have the ability of detecting multiple trend turnings. In this article, we propose a new methodology named as the running slope difference (RSD) 〈em〉t〈/em〉 test to detect multiple trend turnings. This method employs a 〈em〉t〈/em〉-distributed statistic of slope difference to test the sub-series trend difference of the time series, thereby identifying the turning points. We compare the RSD 〈em〉t〈/em〉 test method with some other existing trend turning detection methods in an idealized time series case and several climate time series cases. The results indicate that the RSD 〈em〉t〈/em〉 test method is an effective tool for detecting climate trend turnings.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Researchers have calibrated satellite signals successfully using novel artificial intelligence (AI) methods to estimate discharge at ungauged river sites accurately. However, common AI methods including neural networks have a recognized defect in time series forecasting known as input imitation error. The present study addresses this significant source of error by combining evolutionary polynomial regression (EPR) with the Nondominated Sorting Genetic Algorithm (NSGA-II) for multiobjective optimization. This new method of forecasting signal time series is called the evolutionary polynomial regression-time series predictor (EPR-T). EPR-T can simultaneously minimize the model prediction error based on traditional performance indices as well as a new index, peak similarity (PS), to prevent the model from imitating its input variables when forecasting. The prediction accuracy of the new EPR-T and traditional AI methods is compared for six case studies, namely the Connecticut, Missouri, Pee Dee, Red, White, and Willamette rivers. The results demonstrate the considerably superior accuracy of EPR-T over the regular EPR method.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Understanding the changing characteristics and related mechanisms behind precipitation extremes is crucial for developing adaptive measures of water resource management as well as flood risk management. Based on daily precipitation measurement taken at 57 meteorological stations from 1960 to 2016, the variability of precipitation extremes over the Yangtze River Delta (YRD) is analyzed utilizing a Mann-Kendall trend test as well as a Hurst exponent analysis. Moreover, the climatic teleconnection that occurs from large-scale atmospheric circulation and such precipitation extremes is also investigated with the help of a wavelet coherence analysis. Results indicate that most extreme precipitation indices predominantly exhibit significant positive trends, indicating a wetting trend in the YRD over the past 61 years. Meanwhile, the contribution of precipitation of very wet days to annual total wet-day precipitation increased significantly. Furthermore, the increasing trend of precipitation extremes in the YRD is found to be attributable to the frequency and intensity, rather than to the duration of extreme precipitation events. The patterns of variation in these precipitation extremes reveal dramatic spatial heterogeneity, with extreme events concentrated primarily along the coastal plains. Overall, the YRD will likely face more severe flood risks in the foreseeable future. This is especially the case for the southern and central-western regions of the YRD. In contrast, the northern region of the YRD is forecast to become drier over time. The increasing trends in precipitation extremes for the YRD observed in this study are found to be linked closely with the positive anomalies of the El Niño-Southern Oscillation as well as the negative anomalies of the East Asian summer monsoon.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉One of the solutions for resolving the problem of energy production deficit in Central Africa is to promote renewable energy sources. The knowledge of the solar variability represents a determining factor for design, dimensioning, performance assessment, and energetic management of renewable energy conversion systems. In this work, we analyze the behaviour of solar radiation from diurnal to seasonal time scales for the region of Douala, the largest industrial city of Cameroon. Observed data of temperature, sunshine duration and precipitation, and satellite estimates of solar radiation (from Soda Solar Project) and cloudiness (acquired from Meteosat Second Generation) were used. The results show that the solar radiation annual cycle at Douala can be decomposed into four seasons: the main dry season in December–January–February (DJF) which corresponds to the most illuminated season, the main rainy season in June–July–August–September (JJAS) which is the least illuminated, and two intermediate periods, March–April–May (MAM) and October–November (ON) which correspond to semi-illuminated periods. Using a hierarchical clustering analysis (HCA), we found that Douala usually experiences five main types of solar radiation diurnal cycles depicting very bright to obscure days. A characterization of sky conditions during these five diurnal cycles shows a predominance of low and high opaque clouds during obscure days.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉To solve the problem of low permeability and lower extraction rates of high-mud ores, a surfactant was added as a penetrant to the pregnant leaching solution during column leaching tests. On the basis of the theories of physical chemistry and seepage flow mechanics, the mechanism by which seepage is enhanced under the effects of the surfactant was analyzed. The results show that the action modes of the surfactant were divided into four aspects: changing the wettability of the ore, reducing the viscosity of the leaching solution, adsorbing onto the surface of ore, and enhancing the permeability effect. The findings of column leaching tests demonstrated that permeability was substantially improved by the surfactant. In the later period of leaching, the permeability coefficient was two times higher than that of the control group. Meanwhile, the ore extraction rate increased by approximately 10%. During the leaching process, the surface tension of the solution did not substantially change, and that of the solution with surfactant increased slightly. The kinetics analysis of ore column leaching illustrated that the leaching processes were controlled by both internal diffusion (principal factor) and chemical reaction.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The corrosion behavior and mechanical properties of 316L stainless steel (SS) fabricated via selective laser melting (SLM) were clarified by potentiodynamic polarization measurements, immersion tests, and tensile experiments. The microstructural anisotropy of SLMed 316L SS was also investigated by electron back-scattered diffraction and transmission electron microscopy. The grain sizes of the SLMed 316L SS in the 〈em〉XOZ〈/em〉 plane were smaller than those of the SLMed 316L SS in the 〈em〉XOY〈/em〉 plane, and a greater number of low-angle boundaries were present in the 〈em〉XOY〈/em〉 plane, resulting in lower elongation for the 〈em〉XOY〈/em〉 plane than for the 〈em〉XOZ〈/em〉 plane. The SLMed 316L was expected to exhibit higher strength but lower ductility than the wrought 316L, which was attributed to the high density of dislocations. The pitting potentials of the SLMed 316L samples were universally higher than those of the wrought sample in chloride solutions because of the annihilation of MnS or (Ca,Al)-oxides during the rapid solidification. However, the molten pool boundaries preferentially dissolved in aggressive solutions and the damage of the SLMed 316L in FeCl〈sub〉3〈/sub〉 solution was more serious after long-term service, indicating poor durability.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The relationship between blocking events and mean precipitation frequency (MPF) was investigated in this work for Turkey during 1977–2016. The overall MPF for the examined stations during blocked days (nonblocked days) fluctuated between 0.15 and 0.43 (0.12 and 0.38). The ratio of MPF during the blocked days to nonblocked days ranges between 12 and 38%. During the winter season, the country has higher MPF values during blocked days. The greatest ratio of MPF values during blocked days to nonblocked days is observed in summer due to smaller values of MPF occurring during this season overall. Higher MPF occurs when the event center was located between 0〈sup〉o〈/sup〉 and 30〈sup〉o〈/sup〉 E (mean 0.27, range 0.17–0.51). There is no relationship between blocking duration and MPF for all seasons. There is a positive relationship between blocking intensity and MPF during summer (CC = 0.35, significant at the 95% level) and fall (CC = 0.43, significant at the 95% level). The relationship between blocking longitudinal extent and MPF is significant at the 95% confidence level during the summer and fall seasons with correlation coefficients of 0.29 and 0.25, respectively. A composite of the 10 blocking events associated with the largest MPF demonstrated that there is moist advection via westerly flow into Turkey in all seasons. During winter, a greater proportion of these events is observed during the La Niña phase of El Niño Southern Oscillation, but during El Niño in spring and summer. For the blocking case study (31 October to 5 November 2009) associated with the largest MPF, the mean value across the country was 0.73. The mean total precipitation during this period was 63.4 mm.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, trends of minimum and maximum temperatures in Iran were studied using time series of daily minimum and maximum temperatures of 45 meteorological stations from 1976 to 2005 (as the baseline period). Mann-Kendall test, for maximum and minimum temperature, was obtained 1.85 and 3.56, respectively, which was positive and significant. The slope of the trend line for maximum and minimum temperature was obtained 0.23 and 0.39 °C decade〈sup〉−1〈/sup〉, respectively. In this study, the trend of extreme temperature indicators was also evaluated. According to the obtained results, in annual terms, TX10, FDO, TN10, and IDO indices have had a negative trend at most stations, but TX90, TR20, TNx, TNx, TXn, TN90, SDI, and SU25 indices showed a positive trend. In the seasonal scale, the indices of cold days (TX10) and cold nights (TN10) showed significant negative trends in most seasons. Warm days (TX90) and warm nights (TN90) showed significant positive trends at most stations. The results of future simulations using several general circulation models in different time periods showed that the highest increase in maximum and minimum temperature related to the RCP8.5 scenario in periods of 2071 to 2099. The results also showed that northwest of Iran would have the highest temperature rise. The results also showed that the probability density function of the minimum and maximum temperatures will shift to warmer temperatures. This could be an indication of climate change in the future decades in Iran.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This paper analyses a recently created continuous 305-year (1711–2016) monthly rainfall series for the island of Ireland. The findings are as follows. The excess skewness in the monthly series may be eradicated by using a Box-Cox transformation with parameter equal to 0.6: a value very similar to that found for the U.K. and its regions. There is no evidence of either an overall stochastic trend or of evolving monthly seasonal patterns, but positive linear trends are found for January, March, and December and a negative linear trend is found for July. Analysis of the seasonal and annual series (which require no transformation) confirms the implication from the monthly data that winters have become progressively wetter and summers progressively drier, with the positive linear trend for winter being twice the size of the negative summer trend. Since there is no trend in either spring or autumn rainfall, annual rainfall shows a positive linear trend. Given that the rainfall series exists for over three centuries, breaks and structural shifts in the model were investigated. Five breaks were identified, three of which occurred in the early portion of the series during the eighteenth century. However, trends were found to be much more stable from the middle of the nineteenth century. For the seasonal series, only a single break, at 1790 for the winter series, was found: it was only after this break that winters became wetter; before then, winter rainfall had a negative trend. In terms of predictability, predictions from the model were found to be more volatile during the second half of the eighteenth century and again from 1976 onwards.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Soil moisture (SM) feedback on climate variables especially temperature is an important aspect in land-atmosphere coupling. Based on the Global Land Data Assimilation System (GLDAS) V2.0 SM data and the gridded observational temperature data, we statistically analyze the thermal feedback of SM over North China (NC). The results show that SM exerts a decreasing trend under the background of evident warming over NC, inducing a decadal enhancement of SM feedbacks on the local temperature and extreme hot events. The SM feedback contributes 6% of the total air temperature variation during 1961–2012, while it reaches 36% after the regional warming during 1994–2012. Such SM affecting temperature is mainly reflected in its feedback on daily maximum temperature, which is also intensified during the warm period. The decadal intensification is also found in the feedback of SM on hot extremes. Further analyses show that the abnormal changes of the latent and sensible heat fluxes caused by the SM anomaly are the main reasons that affect the thermal conditions. Besides, the rising Bowen ratio indicates that upward thermal transfer on the land surface is enhanced in recent years, which suggests that the atmosphere is more sensible to the abnormal heating on the ground. This consequently translates into the decadal intensification of the local thermal feedback of SM in summer over NC.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Investigation of precipitation characteristics on daily, monthly, and annual time scales can contribute to gaining important information related to temporal and spatial distribution of precipitation or even flow rate challenges (e.g., hydrological droughts). The low levels of long-term precipitation and high variability in different time scales are considered the main inherent characteristics of climate in Iran. Due to the direct effects of precipitation on water resources, especially on the river flow rate, it is necessary to assess the efficient indices to visualize the variations in the components of water resources. One of the main indices is the precipitation concentration index (PCI) which is known as a strong indicator of the precipitation distribution generally used on annual and seasonal scales. In this study, drought analysis in the Lake Urmia Basin (LUB) located in northwest of Iran was performed with the daily river flow rate and monthly precipitation values within the period of 1984–2013. The results of changes in precipitation indicated that the irregularity of precipitation distribution had grown in spring months. Also, due to the diminishing precipitation trend on the annual time scale, PCI index also increased. It is concluded that LUB detected a significant descending trend on the annual, spring, and winter time scales in the last 30 years. The PCI values were proved high irregularity in summer with PCI amount of 20.1 and most regularity in winter with PCI amount of 10.4. This paper also aims to assess the effects of PCI on the river flow rate along with the flow shortness volume values using hydrometric and rain gauge stations within LUB. The results obtained from the changes in river flow rate and flow shortness volume revealed that the river flow rate has mostly a falling trend. Finally, it was observed that the time when the river flow rate data changed happened after beginning of changes in the precipitation data. A decrease in inflow from 900 million cubic meters up to 14 billion cubic meters with high flow shortness volume may happen in worst conditions. These results highlighted the importance of applying water resources management in LUB.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Cluster extreme event (CEE), which is characterized by large affected area and long duration of extreme weather, has been arousing the worldwide serious concerns due to its severe impact on society. The winter cluster extreme events of low temperature (LT_CEEs) in the northern hemisphere from 1979 to 2013 are identified with a simplified objective method based on ERA-Interim and JRA-25 daily minimum surface air temperature. The probability density function (PDF) distributions of most indices in the winter LT_CEEs derived from the two datasets are well consistent with each other, especially in the occurrence frequency, duration, and affected area. As expected, the downward trend of all indices in recent 35 years under global warming is congruously revealed from both reanalysis. Nevertheless, the various indices of the winter LT_CEEs after 1998 are generally stable accompanied with slight upward trend, which might be closely related to the speed slowdown of global warming but require further investigation. Similar analysis was carried out with the simulated results of BCC_CSM1.1 model under four scenarios of RCP2.6, RCP4.5, RCP6.0, and RCP8.5. The occurrence frequency of the winter LT_CEEs under RCP2.6 remains stable after 2050, but significantly decreases under RCP4.5 and RCP6.0, and disappears under RCP8.5 scenario. Overall, the descent rate of the winter LT_CEEs accelerates with the emission rise.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Surface sensible heat flux (〈em〉SH〈/em〉) and latent heat flux (〈em〉LH〈/em〉) are important variables linking the energy and hydrological cycles over the Tibetan Plateau (TP). Through comparison with eddy covariance observations of turbulent fluxes at two sites from 2013 to 2015 and at eight sites in August 2014 over the TP, five reanalysis flux products were evaluated for monthly mean biases and daily variations after bilinear interpolation. The results showed the JRA-55 and ERA-Interim reanalyses had optimal performances regarding 〈em〉SH〈/em〉, while NCEP2 had reasonable performance regarding 〈em〉LH〈/em〉. The 〈em〉SH〈/em〉 in the reanalysis data generally reached maximum negative biases in winter and minimum positive biases in summer, whereas the seasonal bias of 〈em〉LH〈/em〉 was found opposite to that of 〈em〉SH〈/em〉. The diurnal variation of reanalysis fluxes was found consistent with observed data at most sites, and the diurnal 〈em〉SH〈/em〉 and 〈em〉LH〈/em〉 maxima were all overestimated except 〈em〉SH〈/em〉 in the JRA-55 at Nagri. The 〈em〉SH〈/em〉 bias and the bias of the surface wind speed in NCEP2 were highly significantly correlated, suggesting the bias in the surface wind dominates the 〈em〉SH〈/em〉 bias over the TP in NCEP2. Large spreads of averaged biases and standard deviation errors were found among the five reanalysis bulk variables. In particular, the maximum-minimum ranges of the biases of surface wind speed and ground-air–specific humidity contrast were 〉 5 m s〈sup〉−1〈/sup〉 and 〉 15 g kg〈sup〉−1〈/sup〉, respectively.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Autumn rain of West China (ARWC), a typical climate phenomenon characterized by continuous rainfall, is prone to flooding and secondary disasters. The ARWC in 2017, the greatest one since the last 30 years, resulted in an economic loss of 1.9 billion dollars and serious social impacts. It is thus urgent to understand the cause for this anomaly. In this article, the atmospheric circulations affecting the 2017’s ARWC are identified. They are (1) a dipole pattern with the blocking over Europe and the trough over Lake Balkhash, which favors the southward outbreak of cold airs into West China, (2) increased water vapor transportation toward West China from the Pacific and Indian Oceans, and (3) a strengthening and northward displacement of the East Asian jet stream. The cold sea surface temperature anomaly (SSTA) in the equatorial central Pacific provides a superimposed effect. Further analysis reveals a synergic role in the interannual variability of the ARWC from the anomalies of the atmospheric circulation over Lake Balkhash and the SST in the equatorial central Pacific. The combination of anomalous trough over Lake Balkhash with cold SSTA in the equatorial central Pacific is most favorable for the increase of ARWC, while that of anomalous ridge with warm SSTA generally results in a decrease of ARWC. The combination of anomalous ridge with cold SSTA or that of anomalous trough with warm SSTA has no specific indication for ARWC anomalies.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Based on the principles of massive support and lateral support, a novel double-layered split die (DLSD) for high-pressure apparatus was designed to achieve a higher pressure-bearing capacity and larger sample cavity. The stress distributions of the DLSDs with different numbers of divided blocks were investigated by the finite element method and compared with the stress distributions of the conventional belt-type die (BTD). The results show that the cylinders and first-layer supporting rings of the DLSDs have dramatically smaller stresses than those of the BTD. In addition, increasing the number of divided blocks from 4 to 10 gradually increases the stress of the cylinder but has minimal influence on the stress of the supporting rings. The pressure-bearing capacities of the DLSDs with different numbers of divided blocks, especially with fewer blocks, are all remarkably higher than the pressure-bearing capacity of the BTD. The contrast experiments were also carried out to verify the simulated results. It is concluded that the pressure-bearing capacities of the DLSDs with 4 and 8 divided blocks are 1.58 and 1.45 times greater than that of the BTD. This work is rewarding for the commercial synthesis of high-quality, large-sized superhard materials using a double-layered split high-pressure die.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Herein, the effect of high chloride ion (Cl〈sup〉−〈/sup〉) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO〈sub〉2〈/sub〉 environment was demonstrated. The Cl〈sup〉−〈/sup〉 concentration was varied from 30 to 150 g/L and cyclic potentiodynamic polarization was conducted to investigate the influence of the Cl〈sup〉−〈/sup〉 concentration on the corrosion potential (〈em〉E〈/em〉〈sub〉corr〈/sub〉), passive breakdown potential (〈em〉E〈/em〉〈sub〉pit〈/sub〉), and repassivation potential (〈em〉E〈/em〉〈sub〉rep〈/sub〉). The results of the polarization curves revealed that 13Cr stainless steel is susceptible to pitting under high Cl〈sup〉−〈/sup〉 concentration. The passive breakdown potential and repassivation potential decreased with the increase of Cl〈sup〉−〈/sup〉 concentration. The semiconducting behavior of the passive film was investigated by Mott-Schottky analysis and the point defect model (PDM). It was observed that the iron cation vacancies and oxygen vacancies were continuously generated by autocatalytic reactions and the higher Cl〈sup〉−〈/sup〉 concentration resulted in higher vacancies in the passive film. Once the excess vacancies condensed at the metal/film interface, the passive film became locally detached from the metal, which led to the breakdown of the passive film.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The microstructures of doped tungsten deformed by multi-pass hot continuous rolling were investigated, and the stress and strain fields were simulated by finite element (FE) method. After the continuous rolling, the grains of the tungsten rod were refined, and the microhardness was improved; however, a ring region of abnormal grain growth was present at a distance of about 3/5R (R is the radius of the rod) from the center of the cross section. FE modeling results showed that the equivalent residual strains were minimum around the region of abnormal grain growth; this was due to the release of strain energy by severe plastic deformation, leading a situation where the migration force of grain boundaries was higher than the pinning force of potassium bubbles. By decreasing the initial rolling temperature and rolling speeds, the inhomogeneity of the equivalent residual stain decreased, improving the microstructure uniformity of the doped tungsten.〈/p〉

Description: 〈p〉The original version of this article unfortunately contained a mistake in the HTML version. The name of the cathode in abstract was incorrect. The correct version is given below:〈/p〉 〈p〉A high-energy-density Li-ion battery with excellent rate capability and long cycle life was fabricated with a Ni-rich layered LiNi〈sub〉0.8〈/sub〉Mn〈sub〉0.1〈/sub〉Co〈sub〉0.1〈/sub〉O〈sub〉2〈/sub〉 cathode and SiO-C composite anode. The LiNi〈sub〉0.8〈/sub〉Mn〈sub〉0.1〈/sub〉Co〈sub〉0.1〈/sub〉O〈sub〉2〈/sub〉 and SiO-C exhibited excellent electrochemical performance in both half and full cells.〈/p〉 〈p〉The original article has been corrected.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In the newly developed oxygen-enriched bottom-blowing copper smelting process (also known as the SKS copper smelting process), Cu loss in slag is one of the most concerning issues. This paper presents our research results concerning the relationship between the Cu content of the matte and slag in the SKS process; the results are based on actual industrial production in the Dongying Fangyuan copper smelter. The results show that the matte grade strongly influences Cu losses in slag. The dissolved and entrained losses account for 10%–20% and 80%–90% of the total SKS industrial Cu losses in slag, respectively. With increasing matte grade, the dissolved and entrained Cu losses in the SKS slag both increase continuously. When the matte grade is greater than 68%, the content of Cu in the smelting slag increases much more dramatically. To obtain a high direct recovery of copper, the matte grade should be less than 75% in industrial SKS copper production.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this study, the effects of heating temperature (850–1100°C) and holding time (30–150 min) on the grain growth behavior of austenite in medium-carbon alloy steel were investigated by conducting experiments. The abnormal grain growth and mixed grain structure phenomenon are explained using an equilibrium precipitation phase diagram calculated by Thermo-Calc software package. The AlN particles were observed by field-emission scanning electron microscopy (FESEM), and the amount of AlN precipitations was detected by electron probe microanalysis (EPMA). Based on the research results, it was found that the average grain size of austenite in the test steel increased continuously with the increase of temperature and holding time. Furthermore, the abnormal growth of austenite occurred in the test steel at 950°C, and the heating temperature affected the austenite grain size more significantly. In addition, the decline in the amount of AlN second-phase particle in the test steel, which weakened the “pinning” effect on austenite grain boundaries, resulted in abnormal growth and the development of mixed austenite grain structures. The prediction model for describing the austenite grain growth of medium-carbon alloy steel during heating was established by regression analysis of the experimental data, and the model was verified to be highly accurate.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The statistical characteristics of precipitation play an extremely important role in the risk assessment of drought and flood disasters and water resource management. In this paper, the precipitation concentration degree (PCD), precipitation concentration period (PCP) and precipitation concentration index (PCI) were used to analyse the spatiotemporal variation in precipitation concentration characteristics in China from 1960 to 2015. In addition, the cross-wavelet transform was used to analyse the possible dependencies and spatial characteristics between these three precipitation concentration indices (PCD, PCP and PCI) and monsoon indices (East Asian summer monsoon index, EASMI; South Asian summer monsoon index, SASMI; and South China Sea summer monsoon index, SCSSMI) of nine river basins in China. The results show that the spatial distribution of precipitation concentration indices in China has obvious north-south and east-west variability. China’s precipitation concentration indices are generally declining, with weak volatility. Among these indices, the PCD (〈em〉P〈/em〉 〈 0.05) and PCI (〈em〉P〈/em〉 〈 0.01) have decreased significantly at rates of − 0.005/10 year and − 0.006/10 year, respectively, while there has been no obvious decrease in the PCP. Compared with the PCD before 1978, the PCD in the rainy season after 1978 has decreased. In most areas, the rainy season is concentrated in July every year; however, the rainy season has been delayed in the middle and lower reaches of the Yangtze River and has advanced mainly in the other basins. The PCI has declined since 1978, indicating a decreasing contribution of heavy precipitation to the total annual precipitation, but this change in the PCI has occurred mainly at high-value stations (PCI 〉 0.7), and the PCI at low-value stations has increased. Most of China’s precipitation concentration indices and monsoon indices, as well as the NWRB, have small-scale (2–4 years) or medium-scale (12–15 years) oscillation periods. The oscillation periods between the precipitation concentration indices and monsoon indices in the Yangtze and Pearl River basins are more significant than those in other basins. The results of this study can help to understand the differences among the precipitation concentration characteristics in different basins in China and the intrinsic relationship between these characteristics and the summer monsoon and provide a reference for further research.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Water requirement is sensitive to the impacts of climate change, especially in Bangladesh because of limited freshwater availability in the dry season, despite the fact that the country’s agriculture sector requires large quantities of water for the crop production. Hence, gaining a better understanding of changes in water requirements in Bangladesh during dry periods is important in the management of agricultural water resources. This study assesses the recent impacts of climate change on the design water requirement (DWR) of the Boro rice–growing season in Bangladesh using a frequency analysis over a 5-year period. The reference evapotranspiration (ET〈sub〉ref〈/sub〉), crop evapotranspiration (ET〈sub〉p〈/sub〉), effective rainfall (ERF), and gross irrigation water requirements (GIWR) of Boro rice were estimated based on daily weather data for the period of 1984–2013 using the CROPWAT8.0 model. The results showed the significant decreasing trends of ET〈sub〉ref〈/sub〉 in most of these Boro rice growth stages in all districts. The GIWR of Boro rice and its trends demonstrated significant spatial heterogeneity in the last three decades due to significant changes in the ERF and ET〈sub〉p〈/sub〉. The DWR of Boro rice–growing season also supported the results of the GIWR, and the Weibull probability distribution function (PDF) is found to be an optimal PDF among eight PDFs for the estimation of DWR. Overall, the results indicate that a recent climate change does not only contribute to high water demands for the crop but also result in decrease water requirements due to variations in wind speed, sunshine hours, and relative humidity.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study assesses the high-resolution, 0.11° (12 km), Canadian Regional Climate Model Version 5 (CRCM5), interactively coupled to the one-dimensional Freshwater Lake model (FLake), to predict wintertime precipitation along the Canadian snowbelts of Lake Superior and Lake Huron. CRCM5–FLake was compared against various datasets to evaluate the 20-year (1995–2014) SWE and wintertime precipitation, seven lake-induced precipitation events and lake effect snowfall (LES) predictor variables during the months of December and January. The findings of SWE along both snowbelts in December and January show MBD ≤− 10 mm and ≤− 30 mm, respectively. Similarly, precipitation results along both snowbelts in December and January show MBD ≤− 5 mm and ≤− 10 mm, respectively. The negative biases in simulated SWE and precipitation, predominantly along the snowbelts, suggest that the model may un-realistically represent lake effect processes. Comparison of lake-induced precipitation events also indicates that the model mostly under-predicts the daily accumulated precipitation associated with each event but tends to accurately capture the timing and the general location of the squalls along the snowbelts, though not for highly localised snow bands. Furthermore, lake-wide results of LES predictor variables indicate that the model over-estimates lake surface temperature (LST) for both lakes during December and January and under-estimates ice cover concentrations for both lakes in December. The resultant biases could be attributed to limitations within the coupled RCM because the quality of reproducing lake-induced precipitation in this region is highly dependent on the performance of FLake.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study discusses the role of natural factors and related teleconnections for Indian summer monsoon (ISM) with a special emphasis on later two decades of the last century. The combined influence of the sun and volcanos on ISM is examined using observational data as well as CMIP5 model outputs. Possible mechanisms relating to a disruption of the usual ENSO-ISM teleconnection for those decades are explored. Observation suggested that the regional Hadley circulation, via the NAO in the northern hemisphere and Indian Ocean Dipole in the southern hemisphere, may have a role in the change in ISM behaviour. Such features though captured well in the observation are shown missing in models. Additionally, it indicates that differences among models mainly originate in a regional level, which could be due to inconsistency in representing regional teleconnection features. Interestingly, all models perform reasonably well in terms of global thermodynamic scaling arguments. The overall study underpins important areas, where natural factors influence regional climate, but models miss out and suggest discrepancies among each other. Such knowledge has major implications in regional as well as global scale. The modelling community will also greatly benefit by an improved representation of ENSO and ISM in models.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In the context of global warming, the future spatiotemporal distribution of aerosols in China is a common concern of the government and the scientific community. In this study, the regional climate model RegCM4 is used to simulate the spatiotemporal distribution of anthropogenic aerosols including sulfate, black carbon, and organic carbon in China around 2030 under the RCP4.5 and RCP8.5 scenarios and estimate the contributions of climate difference, emission difference, and extra-regional transport difference to the change of anthropogenic aerosol concentration in the study area. The results show that the annual average concentrations of anthropogenic aerosols around 2030 decreased significantly with respect to those around 2010, and the decrease amplitude of black carbon surface concentration is the smallest, especially in the RCP8.5 scenario. The annual averages for sulfate, black carbon, and organic carbon surface concentrations in the central and eastern parts of China will be 8.5, 1.7, and 3.7 μg m〈sup〉−3〈/sup〉, respectively, under the RCP4.5 scenario, whereas 10.0, 2.2, and 4.4 μg m〈sup〉−3〈/sup〉, respectively, under the RCP8.5 scenario. The surface concentration of sulfate is higher in summer and spring, while lower in winter and autumn. The surface concentrations of black carbon and organic carbon are higher in winter and lower in other seasons. The results of sensitivity experiments demonstrate that the future difference in local emissions between RCP8.5 and RCP4.5 scenarios has the greatest impact on the anthropogenic aerosol concentrations throughout China, while the effects of future climate difference and extra-regional transport difference are much smaller around 2030. For the aerosol column burdens, the effect of future local emission difference between the two scenarios is still dominant, and the effect of extra-regional transport difference becomes very significant during spring and winter for organic carbon and black carbon. The results of this paper suggest that the impacts of future climate difference and extra-regional transport difference between RCP8.5 and RCP4.5 scenarios on anthropogenic aerosols are non-negligible in certain regions and seasons besides the impact of future local emission difference in China around 2030.〈/p〉

Description: 〈p〉Equations 1–4 have been typed wrongly during the steps of corrections and some figures and tables are placed way too far from the citations.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉It is undeniable that winter weather is the most dangerous for all road users. Temperate climate creates winter weather conditions that are definitely challenging for road maintenance specialists: one year can be excessively snowy and relatively warm (high daily accident risk and maintenance costs), while the other would be cold and dry (lack of preparedness, lower maintenance, but higher standby costs). Therefore, with ongoing climate change, it is uncertain what weather can be expected in the future, especially with current predictions claiming climate change will bring higher variability and more frequent weather extremes. In order to estimate future impacts of climate change to road conditions (and traffic safety) during temperate winter, an analysis of climate model predictions was performed, using Lithuania as an example of such climate conditions. The focus of this analysis is on meteorological variables that are unfavourable for roads: number of days when air temperature fluctuates around 0 °C, number of days with snow and number of days with adverse driving conditions. Several time periods were chosen: reference (1986–2005), near-term (2016–2035) and long-term (2081–2100). The projections were made using Coupled Model Intercomparison Project Phase 5 (CMIP5) outputs of 4 Representative Concentration Pathways (RCP2.6, RCP4.5, RCP6.0 and RCP8.5). The data outputs of 3 global circulation models (GFDL-CM3, NorESM1-M and HadGEM2-ES) were statistically downscaled for meteorological stations in different regions of Lithuania in order to create distribution maps of climatic variables in the twenty-first century. Results showed that winter driving conditions should improve, and maintenance levels should decrease by the end of the twenty-first century. Nevertheless, a possibility remains that road maintenance and traffic safety might become less effective due to lack of awareness and preparedness, resulting in sudden and unexpected worsening of driving conditions on a day to day basis.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The gasification characteristics and gasification kinetics of coke in complex CO〈sub〉2〈/sub〉/CO/H〈sub〉2〈/sub〉/H〈sub〉2〈/sub〉O/N〈sub〉2〈/sub〉 systems similar to the gas system of industrial blast furnace (BF) were studied by the method of isothermal thermogravimetric analysis. The experimental gas compositions and the corresponding temperature were chosen according to data reported for industrial BFs. The gasification behavior of coke was described by the Random Pore Model (RPM), Volumetric Model (VM), and Grain Model (GM). Results showed that the gas composition of the coke gasification zone in BF changes slightly and that the temperature is the most important factor affecting coke gasification. The lower activation energy of coke samples (Coke Reaction Index (CRI) 〉 50) is due to the high Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 in the ash, lower degree of graphitization, and larger pore structure. In addition, the choice of kinetic model does not differ substantially in describing the gasification mechanism of coke in a BF.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉NiTi shape memory alloys (SMAs) was developed using the spark-plasma sintering (SPS) process with different average particle size (45 μm and 10 μm) under various temperature. The influence of particle size and temperature on the density, microstructure, and corrosion behavior of the NiTi in simulated body fluid was examined. The porosity decreased with increasing sintering temperature and decreasing particle size, which resulted in an increase in density of the alloy. Increasing the sintering temperature led to the formation of Ni- and Ti-rich intermetallic such as Ni〈sub〉3〈/sub〉Ti and NiTi〈sub〉2〈/sub〉. The formation of these secondary phases influenced the corrosion behavior of NiTi by changing its chemical composition. The planar structure of NiTi was transformed into a dendritic structure at 900°C, which resulted in the formation of uniform oxide and phosphate layers on the entire surface. A high corrosion potential and low corrosion current density were achieved with NiTi prepared with 10 μm particles at 900°C, which exhibited superior corrosion resistance.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The present paper aims to investigate the influence of the current density in the electroplating process on the microstructure, crystal texture transformations, and corrosion behavior of Ni/Co–pumice multilayer nanocomposite coatings. The Ni/Co–pumice composite coatings were prepared by deposition of Ni, followed by the simultaneous deposition of pumice nanoparticles (NPs) in a Co matrix via an electroplating process at various current densities. Afterward, the morphology, size, topography, and crystal texture of the obtained samples were investigated. Furthermore, electrochemical methods were used to investigate the corrosion behavior of the produced coatings in a solution of 3.5wt% NaCl. The results indicated that increasing the plating current density changed the mechanism of coating growth from the cell state to the column state, increased the coating thickness, roughness, and texture coefficient (TC) of the Co (203) plane, and reduced the amount of pumice NPs incorporated into the Ni/Co–pumice composite. The electrochemical results also indicated that increasing the current density enhanced the corrosion resistance of the Ni/Co–pumice composite.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The microstructure, mechanical, and corrosion properties of extruded low-alloyed Mg-〈em〉x〈/em〉Zn-0.2Ca (〈em〉x〈/em〉 = 0,1.0,2.0, 3.0) alloys were investigated in this study. Findings from scanning electron microscope, X-ray diffraction and transmission electron microscopy results indicate that the amount of ternary Ca〈sub〉2〈/sub〉Mg〈sub〉6〈/sub〉Zn〈sub〉3〈/sub〉 phase, as the only secondary phase in 1.0Zn, 2.0Zn, and 3.0Zn alloys, gradually increases with the addition of Zn, while the Mg〈sub〉2〈/sub〉Ca phase was observed in the Mg-0.2Ca alloy only. Zn has a strong effect on the orientation and intensity of textures, which also influence mechanical behaviors, as revealed by electron back-scatter diffraction. Among all the alloys, the Mg-2.0Zn-0.2Ca alloy obtains the maximum tensile strength (278 MPa) and yield strength (230 MPa). Moreover, Zn addition has an evident influence on the corrosion properties of Mg-〈em〉x〈/em〉Zn-0.2Ca alloy, and Mg-l.0Zn-0.2Ca alloy exhibits the minimum corrosion rate. This paper provides a novel low-alloyed magnesium alloy as a potential biodegradable material.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Recent developments in the use of diamond materials as metal-oxide-semiconductor field-effect transistors (MOSFETs) are introduced in this article, including an analysis of the advantages of the device owing to the unique physical properties of diamond materials, such as their high-temperature and negative electron affinity characteristics. Recent research progress by domestic and international research groups on performance improvement of hydrogen-terminated and oxygen-terminated diamond-based MOSFETs is also summarized. Currently, preparation of large-scale diamond epitaxial layers is still relatively difficult, and improvements and innovations in the device structure are still ongoing. However, the key to improving the performance of diamond-based MOSFET devices lies in improving the mobility of channel carriers. This mainly includes improvements in doping technologies and reductions in interface state density or carrier traps. These will be vital research goals for the future of diamond-based MOSFETs.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Low-dimensional nanomaterials such as graphene can be used as a reinforcing agent in building materials to enhance the strength and durability. Common building materials burnt red soil bricks and fly ash bricks were reinforced with various amounts of graphene, and the effect of graphene on the strength of these newly developed nanocomposites was studied. The fly ash brick nanocomposite samples were cured as per their standard curing time, and the burnt red soil brick nanocomposite samples were merely dried in the sun instead of being subjected to the traditional heat treatment for days to achieve sufficient strength. The water absorption ability of the fly ash bricks was also discussed. The compressive strength of all of the graphene-reinforced nanocomposite samples was tested, along with that of some standard (without graphene) composite samples with the same dimensions, to evaluate the effects of the addition of various amounts of graphene on the compressive strength of the bricks.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In current underground mining, the stability of the exposed backfill face is a basic issue associated with mining design and has been the subject of considerable research in mining safety and efficiency. In this study, an improved analytical solution for evaluating the safety of vertically exposed faces in backfilling was proposed. Based on a differential slice method, the proposed solution emphasizes the arching effect as having the advantages of more rigor and wider scalability. Feasibility of the proposed solution was validated with classic centrifuge results. Good agreement between compared results indicated that the proposed solution skillfully predicts the behavior of the paste centrifuge model. Additionally, calculation of exposed face safety in sequential filling was presented. The proposed solution has practical significance in mine backfill design.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The size of underground openings in rock masses in metal mines is critical to the performance of the openings. In this study, the mechanical and acoustic emission (AE) characteristics of brittle rock-like specimens containing a circular opening with different ratios of opening diameter to sample size 〈em〉λ〈/em〉 (〈em〉λ〈/em〉 = 0.1, 0.13, 0.17, 0.2, and 0.23) were investigated under uniaxial compression with AE monitoring. The results indicate that the opening size strongly affected the peak strength and the elastic modulus. Crack initiation first started from the upper surface of the specimens, not from the periphery of the openings. Tensile and shear cracks coexisted on the roof and floor of the specimens, whereas tensile cracks were dominant on the two sides. The fracture mode of samples with openings was partially affected by the relative size of the pillars and openings. The AE response curves (in terms of counts, cumulative energy, cumulative counts, and 〈em〉b〈/em〉-value) show that brittle failure was mainly a progressive process. Moreover, the AE information corresponded well with microcrack evolution in the samples and thus can be used to predict sample failure.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The high-throughput diffusion-multiple technique and thermodynamics databases were used to design new high-strength Ti alloys. The composition–microstructure–property relationships of the Ti64–〈em〉x〈/em〉Mo alloys were obtained. The phase fraction and composition of the α and β phases of the Ti64–〈em〉x〈/em〉Mo alloys were calculated using the Thermo-Calc software. After aging at 600°C, the Ti64–6Mo alloy precipitated ultrafine α phases. This phenomenon was explained on the basis of the pseudo-spinodal mechanism by calculating the Gibbs energy curves of the α and β phases of the Ti64–〈em〉x〈/em〉Mo alloys at 600°C. Bulk forged Ti64–6Mo alloy exhibited high strength and moderate plasticity after α/β-phase-field solution treatment plus aging. The tensile properties of the alloy were determined by the size and morphology of the primary and secondary α phases and by the β grain size.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The present work investigates the hot-corrosion behavior of carbon nanotube (CNT)-reinforced chromium oxide coatings on boiler steel in a molten salt (Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉-60wt%V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉) environment at 700°C under cyclic conditions. The coatings were deposited via the high-velocity oxygen fuel process. The uncoated and coated steel samples were subjected to hot corrosion in a silicon tube furnace at 700°C for 50 cycles. The kinetics of the corrosion behavior was analyzed through mass-gain measurements after each cycle. The corrosion products were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray analysis techniques. The results revealed that uncoated steel suffered spallation of scale because of the formation of nonprotective Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 scale. The coated steel samples exhibited lower mass gains with better adhesiveness of oxide scale with the steel alloy until the end of exposure. The CNT-reinforced coatings were concluded to provide better corrosion resistance in the hot-corrosion environment because of the uniform dispersion of CNTs in the coating matrix and the formation of protective chromium oxides in the scale.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The weldability of the ZhS6U nickel-based superalloy, which is prone to solidification cracking during electron-beam welding (EBW) repair processes, was investigated. The effects of two different pre-weld heat-treatment cycles on the final microstructure before and after welding were examined. Welds were made on flat coupons using an EBW machine, and the two heat-treatment cycles were designed to reduce γ′ liquation before welding. Microstructural features were also examined by optical and scanning electron microscopy. The results showed that the change in the morphology and size of the γ′ precipitates in the pre-weld heat-treatment cycles changed the ability of the superalloy to release the tensile stresses caused by the matrix phase cooling after EBW. The high hardness in the welded coupons subjected to the first heat-treatment cycle resulted in greater resistance to stress release by the base alloy, and the concentration of stress in the base metal caused liquation cracks in the heat-affected zone and solidification cracks in the weld area.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Effective silver recovery is usually restricted by either environmental pollution or high recovery costs. To tackle the issues, this study introduces a novel method for the effective recovery of silver by utilizing the alkaline sodium thiosulfate-potassium ferricyanide leaching system. The reaction kinetics of silver dissolution in this system was investigated via the rotating disk electrode technology. The influences of important parameters, including the rotation speed, sodium thiosulfate concentration, potassium ferricyanide concentration, and temperature, on the silver dissolution rate were systematically investigated. The activation energy was measured to be 17.96 kJ·mol〈sup〉-1〈/sup〉 when the silver dissolution was controlled by a diffusion process. When the silver dissolution was in the region of mixed control, the reaction orders of ferricyanide and thiosulfate were found to be 0.57 and 0.19, respectively, and the reaction orders of ferricyanide and thiosulfate were 0.55 and 0.22, respectively, when the silver dissolution was controlled by surface reaction. This study has great potential for the development of an environmentally friendly silver recovery process from end--of-life products.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The aim of the present study was to investigate the effect of element segregation on the microstructure and γ′ phase in a γ/γ′ cobalt- based superalloy. Several samples were prepared from a cast alloy and homogenized at 1300°C for different times, with a maximum of 24 h. A microstructural study of the cast alloy using wavelength-dispersive spectroscopic analysis revealed that elements such as Al, Ti, and Ni segregated mostly within interdendritic regions, whereas W atoms were segregated within dendrite cores. With an increase in homogenization time, segregation decreased and the initial dendritic structure was eliminated. Field-emission scanning electron microscopy micrographs showed that the γ′ phases in the cores and interdendritic regions of the as-cast alloy were 392 and 124 nm, respectively. The size difference of γ′ was found to be due to the different segregation behaviors of constituent elements during solidification. After homogenization, particularly after 16 h, segregation decreased; thus, the size, chemical composition, and hardness of the precipitated γ′ phase was mostly uniform throughout the samples.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The climatic characteristics of 260 East Asian tropical monsoon depressions (EAMDs) are investigated using the ERA-Interim reanalysis dataset and a tracking dataset of global monsoon low-pressure systems. Most EAMDs form over the South China Sea (SCS) and the western tropical Pacific Ocean in July–October and have an average lifetime of 10 days. The vertical structures of EAMDs are usually upright or tilt slightly westward with height. The warm-over-cold thermal structure is a distinctive characteristic of EAMDs and two potential vorticity (PV) centers are related to the warm core in the upper level and the specific humidity center in the lower level, respectively. We divided the EAMDs into four groups: eastward-moving, westward-moving, turning, and northwestward-moving EAMDs. Most of the eastward-moving EAMDs form over the SCS in May and June, whereas the westward-moving EAMDs form over both the SCS and the western Pacific Ocean in July–October. The turning and northwestward-moving EAMDs are mainly generated over the western Pacific Ocean and have longer lifetimes. The structures of the eastward-moving and turning EAMDs show common characteristics in each stage. Their vertical structures change from upright in the developing and peak stages to northeast tilting with height in the attenuating stage, especially for the specific humidity. By contrast, the structures of westward- and northwestward-moving EAMDs show little change during their lifetime. They are symmetrical relative to the vertical axis of the EAMDs over their whole lifetime and only vary in strength.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉For any given time series, how to optimize its forecast strategies and what prediction model is adopted are of great importance. In order to reach this goal, insight from analyzing predictability of series with known structure information is necessary. Time series generated by theoretical models with four kinds of known predictive structures, i.e., short-term correlation, long-term correlation, and multifractal and chaotic patterns, are applied to demonstrate that there is a well-defined relation between series’ intrinsic predictability and prediction accuracy of any specific prediction model. And results show that both intrinsic predictability and prediction accuracy are enhanced by these well-defined structures. There are different regimes in the relation between intrinsic predictability and prediction accuracy for series with different known deterministic or stochastic predictive structures. These regimes in the relation between intrinsic predictability and prediction accuracy can guide us to preselect a suitable prediction model and forecast strategies for any underlying series by only analyzing the permutation entropy of a given series. Results from three pieces of climate series further confirm that insights from theoretical series with known structure information indeed work well.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Industrial experiments with three types of slags were performed to investigate the effect of slag on oxide inclusions during electroslag remelting (ESR) process. G20CrNi2Mo bearing steel was used as the consumable electrode and remelted using a 2400-kg industrial furnace. The results showed that most inclusions in the electrode were low-melting-point CaO−MgO−Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. After ESR, all the inclusions in ingots were located outside the liquid region. When the slag consisted of 65.70wt% CaF〈sub〉2〈/sub〉, 28.58wt% Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, and 4.42wt% CaO was used, pure Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 were the dominant inclusions in ingot, some of which presented a clear trend of agglomeration. When the ingot was remelted by a multi-component slag with 16.83wt% CaO, a certain amount of sphere CaAl〈sub〉4〈/sub〉O〈sub〉7〈/sub〉 inclusions larger than 5 μm were generated in ingot. The slag with 8.18wt% CaO exhibited greater capacity to control the inclusion characteristics. Thermodynamic calculations indicated that the total Ca and Mg in ingots were attributed from the relics in electrode and strongly influenced by the slag composition. The formation of ingot inclusions was calculated by FactSage〈sup〉TM〈/sup〉 7.0, and the results were basically in accordance with the observed inclusions, indicating that a quasi-thermodynamic equilibrium could be obtained in the metal pool.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this study, we investigate spatial differences in thermal comfort conditions using the net effective temperature (〈em〉NET〈/em〉) considering the synthetic effects of air temperature, relative humidity, and wind speed. Using a daily-scale dataset of maximum air temperature (〈em〉T〈/em〉〈sub〉max〈/sub〉), relative humidity, and wind speed from 518 stations during 1960–2016 across China, we analyze the influence of different climate conditions on 〈em〉NET〈/em〉 or 〈em〉T〈/em〉〈sub〉max〈/sub〉 at three different levels of hot conditions (35 °C 〈 〈em〉T〈/em〉〈sub〉max〈/sub〉 〈em〉〈〈/em〉 37 °C, 〈em〉NET〈/em〉〈sub〉〈em〉T〈/em〉max35〈/sub〉 for 〈em〉HT〈/em〉〈sub〉35〈/sub〉 cases; 37 °C 〈 〈em〉T〈/em〉〈sub〉max〈/sub〉 〈em〉〈〈/em〉 40 °C, 〈em〉NET〈/em〉〈sub〉〈em〉T〈/em〉max37〈/sub〉 for 〈em〉HT〈/em〉〈sub〉37〈/sub〉 cases; 〈em〉NET =〈/em〉 27 °C, 〈em〉NET〈/em〉〈sub〉27〈/sub〉 cases). In 〈em〉HT〈/em〉〈sub〉35〈/sub〉 (〈em〉HT〈/em〉〈sub〉37〈/sub〉) cases, 〈em〉NET〈/em〉〈sub〉〈em〉T〈/em〉max35〈/sub〉 (〈em〉NET〈/em〉〈sub〉〈em〉T〈/em〉max37〈/sub〉) can reach up to 32 °C (34 °C) in southern China and also can be less than 29 °C (31 °C) in western Northwest China. In 〈em〉NET〈/em〉〈sub〉27〈/sub〉 cases as the threshold for the thermal sensation of very hot, 〈em〉T〈/em〉〈sub〉max〈/sub〉 should be over 33 °C in western Northwest China and was less than 30.5 °C in southern China, by contrast. With global warming, there is an increasing trend in the number of extreme hot days in most part of China, but a decreasing trend is detected in the part of Jianghuai region, partly due to the decreasing trend in 〈em〉T〈/em〉〈sub〉max〈/sub〉〈em〉.〈/em〉〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Iran is a part of the arid and semi-arid regions of the world and many of its areas suffer from repeated droughts. Due to the fact that recent droughts have put a lot of pressure on water supply systems, drought management have a particular importance. For this purpose, monitoring and forecasting systems can be considered as appropriate tools. In this research, monitoring and prediction of drought in the Urmia synoptic station in short-, medium-, and long-term timescales were investigated using the SPEI (standardized precipitation and evapotranspiration drought index) and gene expression programming model. For this purpose, the SPEI was calculated for timescales 1, 3, 6, 12, 24, and 48 months with using monthly rainfall and temperature data from 1951 to 2009, and its performance was compared with standard precipitation index (SPI). The results showed that the correlation coefficient of SPEI and SPI in the 3-, 12-, and 48-month timescales were 0.84, 0.845, and 0.776, respectively. The monitoring results showed two long periods of drought-related years 1959–1967 and 1998–2009 during the statistical period. After drought monitoring based on SPEI time series, drought was predicted using gene expression programming models with delays of 1 to 5 months. According to the results, the prediction accuracy was increased by increasing the scale of SPEI so that the correlation coefficient in the test stage in the one-month scale (SPEI1) increased from 0.215 to 0.984 in 48-month scale (SPEI48) and the overall accuracy of the model increased from 60.1 in SPEI1 to 92.3% in SPEI48.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Since the extra-tropical eddies carry a huge amount of moisture, heat, and momentum from their source regions to remote places, the long-term changes in their properties can lead to substantial changes in the Earth’s major climatic zones with huge socio-economic consequences. We present the long-term variability and trends in the spatial properties of the Rossby wave packets (RWPs) in the Northern Hemisphere in all seasons for the period of 1980–2013 using NCEP reanalysis for the three major storm track regions: Eurasian, North Pacific, and North Atlantic. A region of high-amplitude meandering flow in the upper troposphere that in the mid-latitudes travel in coherent wave train structures or wave packets is often referred to as a RWP. We found that the activity volume of the RWPs is largest during winter in all storm track basins. Our results suggest that the highest variability of the activity volume is in the North Atlantic region, while the minimum variability of this quantity is found during summer in the Eurasian basin. The largest relative frequency of significant wave packets is found in winter in the North Atlantic basin; however, the largest variability of this quantity is found in the North Pacific region during spring. The largest variability of the long-term daily maximum of WPA is found in the Eurasian region in winter and the minimum variability of this quantity is found in summer in the North Pacific region. The long-term northernmost point of the Rossby wave packets (which is an indicator of the meridional extent of the RWPs) shows that during autumn in the North Atlantic basin, the Rossby wave packets meander more than other seasons and regions. The minimum value of this quantity is found in the summer season in the Eurasian region. The largest variability of the northernmost edge of the RWPs is found in the autumn season in the Eurasian basin, while the minimum variability of this quantity is found in the autumn season in the North Atlantic region. We employ the non-parametric Mann-Kendall test to identify the statistically significant trends in the spatial properties of the Rossby wave packets. No significant trend is found for any diagnostic tools in any region and any season. This suggests that the global mean temperature rise or other climatic changes (over the 34-year period of this study) do not have a detectable impact on the Rossby wave packets.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Examining the physical mechanisms through which large-scale climate indicators, e.g., El Niño–Southern Oscillation and Indian Ocean Dipole, affect hydroclimatic variables in the tropics and extratropics is a forefront scientific challenge. We examined climatic teleconnections between large-scale climate indices and temperature variability over South Korea. To do this, we calculated not only leading patterns of observed monthly mean and extreme temperature through an empirical orthogonal teleconnection (EOT) decomposition technique but also statistical correlations on a monthly basis using cross-correlation and lag regression analyses for the leading modes and global atmospheric circulation dataset. As a result, the spatial pattern of the leading EOT modes for mean (extreme high) temperature represents an eastern (southern) coastal mode for boreal summer and a northern (middle) inland mode in boreal winter, while extreme low EOTs exhibit a northern inland mode in summer and a western coastal mode in winter. The temporal evolution of the leading EOT modes exhibits a mostly increasing trend and an interdecadal oscillation. The leading EOT modes of mean temperature explain more variance than those of extreme temperature during warm and cold seasons. The findings from this study illustrate that tropical ENSO forcing has a coherent association with August and December temperature patterns, while the Indian Ocean Dipole is identified as a driver for temperature variability during fall season. The monsoon circulation over the western North Pacific also exhibits a significant negative correlation with the December temperature EOTs. The leading EOTs for October temperature exhibit the positive correlation with the tropical cyclone variability, while the leading EOTs for mean and extreme high temperature exhibit significant negative correlations with the snow depth over northeastern Eurasia in November. The leading patterns of the August and December mean temperature time series are predictable at up to 5-month lead time from the tropical Pacific sea surface temperatures (SSTs), while a predictable response from Indian Ocean SSTs was detected at up to 4-month lead time.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The characteristics of eolian sand activity are greatly influenced by the wind regime, and wind regimes have been changing around the world in response to climate change. This has also been true in the desert area of northwestern China since 1965, and these changes have changed the region’s landforms, sandstorm frequency, and desertification. In this study, we analyzed the temporal and spatial variation of the region’s near-surface wind field since 1965. We found an average annual wind speed during this period of 1.7 m s〈sup〉−1〈/sup〉, with a decreasing trend from 1965 to 2000 and an increasing trend from 2000 to 2015. The maximum rate of decrease occurred in the spring and in the eastern Taklimakan Desert. The variation of the average wind speed depended on the frequency of winds strong enough to entrain sand (with a wind speed 〉 6 m s〈sup〉−1〈/sup〉). We also found that variations of the drift potential were primarily controlled by three prevailing wind groups (winds from the northwest, north, and northeast), but showed complex changes between seasons and regions. The wind direction in the Taklimakan Desert is characterized by two characteristics of branch and steering, the branch line is swinging in the direction of the east and the west (81.5° E~84° E). The changes in wind speed were mainly caused by a decreased frequency of strong winds, precipitation, and urban development. However, the variation of wind speed had less impact on the desert environment than the variation of wind direction.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The paper focuses on investigation of ‘twin’ subtropical oceanic highs of the Northern Hemisphere, i.e. the Azores High (AH) and the Hawaiian High (HH) in January and July based on gridded 2.5° × 2.5° data of Reanalysis Project of the National Center for Atmospheric Research for the period 1948–2018. The aim is to answer three questions: (1) Are there any connections between AH and HH (both within and between the systems)? (2) What is the long-term variability and trends of the basic characteristics of AH and HH? (3) Do the AH and HH move, and if so, in what directions? The most important results are as follows: (1) the long-term trend of sea level air pressure in the AH centre in January is positive, statistically significant with the increase of 0.63 hPa/10 years, (2) pressure in both centres significantly relates with the latitude of each system; variables characterising the HH in January explain 11% of variation of the variables of the AH in July, (3) the NE-SW/SW-NE index proves the shifting of the AH in January from the south-west to the north-east from the 1990s of the twentieth century and again to the south-west in the twenty-first century, (4) the HH in January and July moved generally from the north-east to the south-west until the end of the twentieth century and shifted again to north-east during the twenty-first century, (5) the AH in July was characterised by complicated displacement system with the prevalence of the shifting from the north-east to the south-west with the exception for the period 1980–1990. In winter, the AH moves towards the land area of Europe in the second half of the twentieth century, while the HH moves towards the open Pacific. The statistically significant increase of pressure in the centre of the AH in January is closely related to the shifting of the system to the north-east. The positive pressure trend in the centre of the AH in January combined with the zero trend in July is the cause of diminishing difference between summer and winter air pressure value of the high. Due to increased sea surface temperature of the Atlantic, the AH does not lose its strength in winter as it used to a few decades ago.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this study, the long-range relationships between North Atlantic Oscillation (NAO) and precipitation data obtained from Climate Prediction Centre (CPC) Merged Analysis of Precipitation (CMAP) from 1979 to 2016 are investigated using Detrended Fluctuation Moving Average Cross-Correlation Analysis (DMCA). In the atmosphere, teleconnections through strong convective processes sporadically affect various climatic regimes in Europe, Mediterranean basin, North Africa, Middle East, and Caucasus. The NAO is one of the teleconnection processes and results in heavy rainfall in the Mediterranean basin during its negative phase while it gives rise to rain in Europe during its positive phase. The DMCA technique shows that the NAO fluctuation series exhibit different long-range cross-correlation coefficients, ρDMCA(〈em〉s〈/em〉) with “s” being the moving average time window length, between the precipitation values and NAO. Large ρDMCA(〈em〉s〈/em〉) coefficients with time window(s) larger than 12 months were obtained particularly over the Mediterranean basin, near the North Pole including northern Europe. Furthermore, the ρDMCA(〈em〉s〈/em〉) coefficients were grouped into clusters using K-mean method to distinguish the similar patterns. The 1st cluster refers to the negative phase of the NAO indicating warm-rainy conditions and dry spells, which is especially evident in the Mediterranean basin. The 2nd cluster represents the long-range cross-correlation with respect to the positive phase of NAO and precipitation values, particularly for the Western and Northern Europe. Conversely, the 3rd cluster is evaluated as power law of long-range cross-correlations between the precipitation and NAO with respect to the different time scale processes.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Many hydrometeorological studies have evaluated the impact of climate variability on hydrologic extremes. Recent studies have shown that the varying state of climatic cycles has intensified the regional hydrologic cycle within a wide range of geographical regions in the state of Texas. These climatic cycles define numerous sea surface temperature and pressure anomalies which lead to heavy precipitation in a region. The objective of this paper is to quantify the impact of five major Atlantic and Pacific Ocean related climatic cycles, including (i) Atlantic Multidecadal Oscillation (AMO), (ii) North Atlantic Oscillation (NAO), (iii) Pacific Decadal Oscillation (PDO), (iv) Pacific North American Pattern (PNA), and (v) Southern Oscillation Index (SOI), on maximum daily precipitation within a year in various climate regions of Texas, using a weighted correlation approach incorporating Leave-One-Out Test (LOOT). The uncertainty in the estimated correlation coefficient is factored in by determining the sample correlation coefficient at the 95% confidence interval. The influence of these global scale climatic cycles on the regional hydrologic cycle is found to be governed by the integrated hydrometeorological properties of weather stations, including (i) station elevation, (ii) average temperature, and (iii) average total precipitation, in the months of extremes. Results of this study will help regional water boards prepare for extreme hydrometeorological events in a changing climate.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Updating the urban land cover information has been proved a necessary method for the numerical studies of urban climate and urban atmospheric environment in China, a fast urbanizing country. However, there are uncertainties in the urban land use/cover (ULUC) information in different datasets due to the uncertainties in raw data sources and produce methods. In this study, the Weather Research and Forecasting model is used to simulate the summer climate over the Yangtze River Delta in July and August 2013, when a heatwave episode occurred. Five numerical experiments are designed; one is the baseline experiment (non-urban land cover (NOURB)) in which all urban land covers are removed, and different urban land use/cover (ULUC) experiments from four different global land cover datasets are used in other four experiments. The differences between the ULUC experiments and the NOURB experiment are used to observe the urbanization effects. The results show a remarkable urbanization effect in all the ULUC experiments, and the urbanization influences are most different over the 〈em〉union-urban〈/em〉 area, which defined as the area marked as urban area by at least one land cover dataset, because the uncertainties in urban land cover information are greatest in this area. All the ULUC experiments show the regional influence of urbanization as well, which means urbanization effects are not limited in cities. The Climate Change Initiative (CCI) experiment using the European Space Agency CCI 2013 dataset showed the greatest urbanization influence and the highest effect index in all analyzed variables, because of the largest urban land cover area in the analysis domain. The urban land cover area in the Global Land Cover experiment is the smallest among the ULUC experiments, but it distributes in a more concentrated way than in other experiments; it indicates that both city size and city shape affect the regional influence.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Over the past century, extreme precipitation events have posed many problems on socio-economic status of India, a country that spans over a wide variety of climate regimes. Assessment of past changes in precipitation associated climate change indicators is very essential for effective management of the hydroclimatic risks. Present study evaluates spatio-temporal variation of eleven precipitation-based climate change indices over three 35-year epochs, i.e., 1906–1940, 1941–1975, and 1976–2010. The analysis is undertaken with the annual and monsoon season (June–September) daily precipitation data separately. Regions of significant changes are identified across the country, reflecting different characteristics (magnitude, frequency, intensity, and duration) of precipitation-based climate change indices. The results indicate a clear temporal evolution in the spatial distribution of trends over the years. During the recent epoch (1976–2010), a split is noticed with segregated increasing trends in southern region and patches of decreasing trends in northern region of the country. In contrast to the indices derived with monsoonal daily precipitation, significant trends over the country were more prominent for the indices derived with annual daily precipitation. Duration of annual maximum dry spell (wet spell) is found to significantly increase (decrease) over most of the regions. However, there is no change in total precipitation indicating an increase in short spell heavy rainfall events. The analysis and the results offer an opportunity to identify the regions of interest and to adopt revised water management policies in the future through revised water allocations, alteration of cropping pattern, etc.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this study, an attempt has been made to analyze long-term annual and seasonal rainfall trends along with change point of annual rainfall in West Bengal, India for 102 years (1901 to 2002) using monthly rainfall data of 18 rainfall stations. The Mann-Kendall test is used to identify trend in rainfall time series and Theil-Sen’s slope estimator to assess the magnitude of this trend. Trend-free pre-whitening method is used to eliminate the influence of significant lag-1 correlation from the series. Change in magnitude is derived in terms of percentage change over mean rainfall. Pettitt-Mann-Whitney and standard normal homogeneity test have been used to identify change point of annual rainfall. The results show that significant trend is found at five stations in annual rainfall, six stations in monsoon rainfall, and eight stations in postmonsoon rainfall. Maldah station has recorded highest negative change in magnitude in annual (− 14%) as well as monsoon rainfall (− 20.48%). South 24 Parganas rainfall station exhibits highest positive change in magnitude in annual (+ 13.98%) and monsoon (+ 13.27%) rainfall. Postmonsoon rainfall portrays positive change in magnitude at 16 rainfall stations with highest change in Birbhum station (+ 40.07%). Three most probable change point years of annual rainfall, viz. 1956, 1967, and 1952 have been observed for the rainfall stations situated in northern, southern, and western part in West Bengal. In the post change point period, the number of rainfall stations with decreasing trend has risen in northern and western part whereas it has lessened in southern part.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The article deals with annual and multiannual courses of the highest monthly precipitation in the Polish and the Ukrainian Carpathians on the basis of the data from 27 measuring stations in the period from 1984 to 2013. The monthly precipitation variability in terms of the highest values in the annual, decadal and the 30-year dimension, taking into consideration the spatial coverage, is the key to the understanding of the precipitation climates of the Carpathian mountain regions with distinctive local features of climate change. The highest monthly amounts of precipitation are regularly observed in the period from May to September and only occasionally in the rest of the months. In winter months, the frequency of occurrence of the highest monthly precipitation totals does not exceed 1%. The highest monthly total precipitation in the whole period out of all the stations was recorded in the most western part of the Polish Carpathians and in the central part of the Ukrainian Carpathians. July 2008 was the only month when the highest monthly precipitation in a year was observed at all stations. The range of the highest monthly precipitation values is broader in the Ukrainian part. Cyclonic circulation patterns are the predominant cause of the highest monthly precipitation in both the Polish and the Ukrainian Carpathians. The findings suggest no significant trends, no apparent patterns in the temporal and spatial distribution of the highest monthly precipitation cases with the biggest number of the highest monthly precipitations cases in the last decade and the prevalence of the cases in the warm period.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The synthesis of a copper(II) oxide-montmorillonite composite and its application in the removal of lead(II) ions in solution were investigated. The Acros Organics (ACOR) montmorillonite was activated using potassium hydroxide solution. The activated ACOR mont-morillonite was titrated with copper(II) nitrate solution to produce the copper(II) oxide-montmorillonite composite. Adsorption experiments were conducted using batch-mode techniques under reducing conditions at ambient temperature. The reaction mechanism indicated a higher proton coefficient, greater intraparticle diffusion, and higher mass transfer rates compared with those achieved with bare montmorillonite. The intraparticle diffusion constant derived from the slope was 2.93〈sup〉-3〈/sup〉 (mg.g〈sup〉-1.〈/sup〉min〈sup〉-0.5〈/sup〉), and the intercept 〈em〉C〈/em〉 was 9.86, # 0. In the presence of a CuO coating, the adsorption efficiency was 85.55% at pH 4 and 89.62% at pH 7. Therefore, the copper(II) oxide-montmorillonite composite, as a novel adsorbent with a very high adsorption capacity, exhibited substantially enhanced adsorption of Pb〈sup〉2+〈/sup〉 ions compared with bare montmorillonite.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The combustion characteristics of two kinds of unburned pulverized coal (UPC) made from bituminous coal and anthracite were investigated by thermogravimetric analysis under air. The reaction kinetics mechanisms between UPC and CO〈sub〉2〈/sub〉 in an isothermal experiment in the temperature range 1000-1100°C were investigated. The combustion performance of unburned pulverized coal made from bituminous coal (BUPC) was better than that of unburned pulverized coal made from anthracite (AUPC). The combustion characteristic indexes (〈em〉S〈/em〉) of BUPC and AUPC are 0.47 × 10〈sup〉−6〈/sup〉 and 0.34 × 10〈sup〉−6〈/sup〉 %2·min〈sup〉−2〈/sup〉·°C〈sup〉−3〈/sup〉, respectively, and the combustion reaction apparent activation energies are 91.94 and 102.63 kJ·mol〈sup〉−1〈/sup〉, respectively. The reaction mechanism of BUPC with CO〈sub〉2〈/sub〉 is random nucleation and growth, and the apparent activation energy is 96.24 kJ·mol〈sup〉−1〈/sup〉. By contrast, the reaction mechanism of AUPC with CO〈sub〉2〈/sub〉 ollows the shrinkage spherical function model and the apparent activation energy is 133.55 kJ·mol〈sup〉−1〈/sup〉.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Historical temperature records are often partially biased by the urban heat island (UHI) effect. However, the exact magnitude of these biases is an ongoing, controversial scientific question, especially in regions like China where urbanization has greatly increased in recent decades. Previous studies have mainly used statistical information and selected static population targets, or urban areas in a particular year, to classify urban-rural stations and estimate the influence of urbanization on observed warming trends. However, there is a lack of consideration for the dynamic processes of urbanization. The Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), and Pearl River Delta (PRD) are three major urban agglomerations in China which were selected to investigate the spatiotemporal heterogeneity of urban expansion effects on observed warming trends in this study. Based on remote sensing (RS) data, urban area expansion processes were taken into consideration and the relationship between urban expansion rates and warming trends was investigated using data from 975 meteorological stations throughout China. Although urban areas constitute less than 1% of land in China, more than 90% of the meteorological stations experienced urban land use change and the average urban expansion rate was 0.33%/a. There was also a significant positive relationship between observed warming trends and urban expansion rates. Background warming, without the influence of urbanization and extra warming induced by urbanization processes, was estimated using a linear regression model based on observed warming trends and urban expansion rates. On average, urbanization led to an additional annual warming of 0.034 ± 0.005 °C/10a. This urbanization warming effect was 0.050 ± 0.007 °C/10a for minimum temperatures and 0.008 ± 0.004 °C/10a for maximum temperatures. Moreover, it appeared that urbanization induced greater warming on the minimum temperature during the cold season and maximum temperature during the warm season.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Due to increasing heat-related health risks, as well as the human requirements on energy and side effects, this study attempts to figure out a methodology of quantifying the potential requirements on human thermal comfort and air humidity towards the achievements of the Sustainable Development Goals (SDGs). Based on the Köppen-Geiger climate classification and the selected 11 climate types with sample cities, the methodology has been detailed. Meanwhile, the quantified thermal and humid conditions in each city, as the primary representation of each climate type, have been presented. According to the potential application of the quantified information and based on the qualitative analysis of SDGs text, the correlation between the information of human thermal comfort and air humidity, and 12 SDGs has been summarised. Furthermore, the difference of the qualitative description between the original Köppen-Geiger climate classification and the quantified information has been discussed. For instance, obvious difference appeared in the same climate zone (e.g. climate zone C); comparing with the original climate classification, there is a different order of hot/cold conditions or wet/dry conditions. The identified differences are regarded as the enlightenments for further studies.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This study uses a multi-model ensemble (MME) for the assessment of the spatial and temporal variations of rainfall in peninsular Malaysia under climate change scenarios. The past performance approach was used for the selection of GCM ensemble from a pool of Coupled Model Intercomparison Project Phase 5 (CMIP5) GCMs. The performances of four bias correction methods, namely, scaling, gamma quantile mapping, generalized quantile mapping, and power transformation were assessed to select the most suitable method for the downscaling of daily rainfall of selected GCMs based on APHRODITE rainfall at a spatial resolution of 0.25° × 0.25°. The downscaling model was used for the projections of daily rainfall for the period 2010–2099 for four representative concentration pathways (RCP) scenarios, namely, RCP2.6, RCP4.5, RCP6.0, and RCP8.5. Random forest regression algorithm was used to develop the multi-model ensemble (MME) mean of GCM-projected rainfall for different RCPs in order to show the changes in rainfall for three future periods, 2010–2039, 2040–2069, and 2070–2099. The results revealed four GCMs, BCC-CSM1.1(M), CCSM4, CSIRO-Mk3.6.0, and HadGEM2-ES as the most suitable GCMs for the projection of daily rainfall of peninsular Malaysia. The power transformation was found as the most suitable method for the correction of biases in GCM daily rainfall. The MME mean of projected rainfall showed the increase in rainfall in peninsular Malaysia for all the scenarios and future periods. The maximum increase in annual rainfall was projected by 15.72% during 2070–2099 for RCP8.5. The variability of future rainfall was also found to increase along with mean rainfall. The increase in rainfall variability was projected by 26.15% for RCP8.5 during 2070–2099. The spatial pattern of rainfall changes revealed more variability in future rainfall in the northeast where frequency of hydro-climatic disasters is higher compared to other regions. The results indicate the possible increase in hydro-climatic disaster in peninsular Malaysia due to climate change.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The Taiwan government has been following the green energy policy for decades to cope with drastic climate change due to global warming and tremendous urbanization. Forming a database to assist Taiwanese policy makers in using the concept of energy efficiency and environmental comfort in urban planning and architectural design is required. This paper depicts how the field and CFD studies for an industrial region located in rural and monsoon wind prevailed district of the mid-western coast Taiwan were conducted, and how the data are used to construct building layout principles for regions having similar climate conditions. For the purpose of analyzing field data and forming database, measured atmospheric and microclimate parameters, such as the physiological equivalent temperature (PET), were first converted into empirical relations. Then, these empirical equations were used as the input and validating values for the CFD simulation model based on the FLUNENT software. Five field-observed wind profiles were used as the inlet conditions, and the computed results of the five-street canyon aspect ratio, and of four-building arrangements, are analyzed to construct the building layout principles. The study results show that the principles for a monsoon wind prevailed region should better be the following: (1) the street canyon aspect ratio is 0.1 and not over 0.3; (2) the building layout is a single open arrangement, avoiding a staggered setting.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The present study examines the prominent patterns of Indian Ocean dipole (IOD) associated with the recent changes in the Pacific Ocean variability centered around 1998. EOF analysis of boreal fall (September through November (SON)) Indian Ocean sea surface temperature anomaly (SSTA) reveals that EOF1 (32% variability) is dominated by East Pacific El Niño-IOD co-occurring pattern during 1980–1998 (period 1). During period 2 (1999–2016), central Pacific El Niño also influence EOF1 (26% variability) and the IOD co-occurrence is reduced. EOF2 with 22% variability has central Indian Ocean dipole pattern co-occurred with El Niño Modoki during period 1, and it became basin-wide south-north dipole pattern in period 2 with reduced (20%) variability. At the same time, local Indian Ocean variability induced by SST anomalies centered on western side of Australia (Ningaloo Niño/Niña) is found to be related to EOF2 in both the periods and its influence is stronger after 1998, when its association with El Niño weakens. Third mode is ENSO independent IOD pattern in both the epochs and has more variability in period 2. Thus, during period 1, both East Pacific and central Pacific El Niño events are well separated as major two modes of tropical Pacific Ocean. These two flavors are associated with two different IOD patterns. But in the second period, first mode of Pacific Ocean is strongly related to both the El Niño flavors and reduced the co-occurrence of IOD with the El Niño modes and the effect of local Indian Ocean processes in the IO variability is intensified.〈/p〉