ALBERT

Description: We describe herein a measurement of the Antarctic surface “roughness” performed by the balloon-borne ANITA (ANtarctic Impulsive Transient Antenna) experiment. Originally purposed for cosmic-ray astrophysics, the radio-frequency (RF) receiver ANITA gondola, from its 38 km altitude vantage point, can scan a disk of snow surface 600 km in radius. The primary purpose of ANITA is to detect RF emissions from cosmic rays incident on Antarctica, such as neutrinos which penetrate through the atmosphere and interact within the ice, resulting in signal directed upwards which then refracts at the ice-air interface and up and out to ANITA, or high-energy nuclei (most likely irons or protons), which interact in the upper atmosphere (at altitudes below ANITA) and produce a spray of down-coming RF which reflects off the snow surface and back up to the gondola. The energy of such high-energy nuclei can be inferred from the observed reflectedsignal only if the surface reflectivity is known. We describe herein an attempt to quantify the Antarctic surface reflectivity, using the Sun as a constant, unpolarized RF source. We find that the reflectivity of the surface generally follows the expectations from the Fresnel equations, lending support to the use of those equations to give an overall correction factor to calculate cosmic ray energies for all locations in Antarctica. The analysis described below is based on ANITA-II data. After launching from McMurdo Station in December, 2008, ANITA-II was aloft for a period of 31 days with a typical instantaneous duty cycle exceeding 95%.

Description: [1]  The Role of aerosols effect on two tropical cyclones over Bay of Bengal are investigated using a convection permitting model with two-moment mixed-phase bulk cloud microphysics scheme. The simulation results show the role of aerosol on the microphysical and dynamical properties of the cloud and bring out the change in efficiency of the clouds in producing precipitation. The tracks of the TCs are hardly affected by the changing aerosol concentrations, but the intensity exhibits significant sensitivity due to the change in aerosol concentration. It is also clearly seen from the analyses that higher heating in the middle troposphere within the cyclone center is in [2]  response to latent heat release as a consequence of greater graupel formation. Greater heating in the middle level is particularly noticeable for the clean aerosol regime which causes enhanced divergence in the upper level which, in turn, forces the lower level convergence. As a result, the cleaner aerosol perturbation is more unstable within the cyclone core and produces a more intense cyclone as compared to the other two aerosol perturbations. This study along with previous simulations show the robustness of the concept of TC weakening by storm ingestion of high concentrations of CCN. The consistency of these model results gives us confidence in stating there is a high probability that ingestion of high CCN concentrations in a TC will lead to weakening of the storm but has little impact on storm direction . Moreover, as pollution is increasing over the Indian sub-continent, this study suggests pollution may be weakening TCs over the Bay of Bengal.

Description: [1]  In this paper, temporal and spatial analyses are employed to detect seismo-ionospheric precursors (SIPs) in the ionospheric total electron content (TEC) during 16 October 1999 M w 7.1 Hector Mine earthquake. To discriminate anomalies caused by global effects, such as solar radiations, magnetic storms, etc., and local effects, such as earthquake, we cross-examine the GPS TECs and their gradients in the eastward and northward directions at epicenter/centers of the Hector Mine area and the other two reference areas at similar magnetic latitudes in Europe and Japan. Temporal variations of the northward TEC gradient suggest SIPs most likely appearing day 6-5 before the earthquake. A global search by using the TEC of GIM (global ionosphere map) shows that the TEC increase and decrease anomalies continuously and specifically appear around the epicenter day 5 before the earthquake.

Description: Abstract Heterogeneous ice nucleating particle (INP) concentrations are reported for a site on the eastern margin of Beijing, China during the period 4 May – 4 June 2018. INP concentrations were measured continuously at ‐20, ‐25 and ‐30 °C in a repeating cycle by a newly developed, automated continuous flow diffusion chamber, and reached concentrations as high as 2800 sL‐1 during dust‐impacted periods. Study‐average concentrations were 70 ± 70, 230 ± 290 and 430 ± 500 sL‐1 at ‐20, ‐25, and ‐30 °C. There was no clear relationship between pollution periods, identified based on fine‐mode particle concentration increases, and INP concentrations or characteristics. Other anthropogenic emissions, such as non‐combustion industrial or agricultural activities play an unresolved role.

Description: Abstract Atlantic Meridional Overturning Circulation (AMOC) disruption during the last deglaciation is hypothesized to have caused large subsurface ocean temperature anomalies, but records from key regions are not available to test this hypothesis, and other possible drivers of warming have not been fully considered. Here, we present the first reliable evidence for subsurface warming in the South Atlantic during Heinrich Stadial 1, confirming the link between large‐scale heat redistribution and AMOC. Warming extends across the Bølling‐Allerød despite predicted cooling at this time, thus spanning intervals of both weak and strong AMOC indicating another forcing mechanism that may have been previously overlooked. Transient model simulations and quasi‐conservative water mass tracers suggest that reduced northward upper ocean heat transport was responsible for the early deglacial (Heinrich Stadial 1) accumulation of heat at our shallower (~1,100 m) site. In contrast, the results suggest that warming at our deeper site (~1,900 m) site was dominated by southward advection of North Atlantic middepth heat anomalies. During the Bølling‐Allerød, the demise of ice sheets resulted in oceanographic changes in the North Atlantic that reduced convective heat loss to the atmosphere, causing subsurface warming that overwhelmed the cooling expected from an AMOC reinvigoration. The data and simulations suggest that rising atmospheric CO2 did not contribute significantly to deglacial subsurface warming at our sites.

Description: Based on the experiments of pulverized coal pneumatic conveying using nitrogen as carrier, the influences of riser inlet height above the gas distribution plate, riser diameter, pulverized coal external moisture content, and supplemental gas flow rate on the conveying characteristics such as pulverized coal mass flow rate and solid-gas ratio were investigated in a laboratory-scale experimental setup of a top-discharge blow tank under atmospheric pressure. There exists an optimal riser inlet height for a given top-discharge blow tank. The supplemental gas is one of the critical factors affecting the conveying stability and continuity. A model for material mass flow rate prediction with errors ranging from –25 % to +15 % is presented. Dense-phase pneumatic conveying of pulverized coal has been widely employed to feed the coal to the gasifier. The blow tank is one of the most important instruments in the dense-phase conveying system. The influences of riser inlet height, riser diameter, pulverized coal external moisture content, and supplemental gas flow rate on the conveying characteristics are investigated.

Description: Achieving higher canopy photosynthesis rates is one of the keys to increasing future crop production; however, this typically requires additional water inputs because of increased water loss through the stomata. Lowland rice canopies presently consume a large amount of water, and any further increase in water usage may significantly impact local water resources. This situation is further complicated by changing environmental conditions such as rising atmospheric CO 2 concentration ([CO 2 ]). Here we modeled and compared evapotranspiration of fully developed rice canopies of a high-yielding rice cultivar ( Oryza sativa L. cv. Takanari) with a common cultivar (cv. Koshihikari) under ambient and elevated [CO 2 ] (A-CO 2 and E-CO 2 , respectively) via leaf ecophysiological parameters derived from a free-air CO 2 enrichment (FACE) experiment. Takanari had 4–5% higher evapotranspiration than Koshihikari under both A-CO 2 and E-CO 2 , and E-CO 2 decreased evapotranspiration of both varieties by 4–6%. Therefore, if Takanari was cultivated under future [CO 2 ] conditions, the cost for water could be maintained at the same level as for cultivating Koshihikari at current [CO 2 ] with an increase in canopy photosynthesis by 36%. Sensitivity analyses determined that stomatal conductance was a significant physiological factor responsible for the greater canopy photosynthesis in Takanari over Koshihikari. Takanari had 30–40% higher stomatal conductance than Koshihikari; however, the presence of high aerodynamic resistance in the natural field and lower canopy temperature of Takanari than Koshihikari resulted in the small difference in evapotranspiration. Despite the small difference in evapotranspiration between varieties, the model simulations showed that Takanari clearly decreased canopy and air temperatures within the planetary boundary layer compared to Koshihikari. Our results indicate that lowland rice varieties characterized by high stomatal conductance can play a key role in enhancing productivity and moderating heat-induced damage to grain quality in the coming decades, without significantly increasing crop water use. This article is protected by copyright. All rights reserved.

Description: Microlites (minute spherulitic, dendritic, skeletal, acicular and poikilitic crystals) diagnostic of crystallization in quenched melt or glass in fault rocks have been used to infer fossil earthquakes. High-pressure microlites and crystallites are described here in a variably eclogitized gabbro, the wallrock to the coesite-bearing eclogite breccia at Yangkou in the Chinese Su-Lu high-pressure metamorphic belt. The studied hand specimens are free of discernible shear deformation, although microfractures are not uncommon under the microscope. In the least eclogitized gabbro, the metagabbro, stellate growths of high-pressure minerals on the relict igneous minerals are common. Dendritic garnet crystals (〈1−5 μ m) grew around rutile and/or phengite replacing ilmenite and biotite, respectively. Skeletal garnet also rims broken flakes of igneous biotite and mechanically twinned augite. Radial intergrowths of omphacite and quartz developed around relict igneous orthopyroxene and are rimmed by skeletal or poikilitic garnet. Acicular epidote, kyanite, and phengite crystallites are randomly distributed in a matrix of Na-rich plagioclase, forming the pseudomorphs after igneous plagioclase. In the more eclogitized gabbro, the coronitic eclogite located closer to the eclogite breccia, all the igneous minerals broke down into high-pressure assemblages. Thick coronas of poikilitic garnet grew between the pseudomorphs after igneous plagioclase and ferromagnesian minerals. The igneous plagioclase is replaced by omphacite crystallites, with minor amounts of interstitial phengite and kyanite. Thermodynamic modelling of the plagioclase pseudomorphs shows an increase in P-T in the wallrock from the metagabbro to the coronitic eclogite, and the P-T variation is unrelated to H 2 O content. The pressure overstepping scenario due to lack of fluid is unsupported both by phase diagram modelling and by whole-rock chemical data, which show that the various types of eclogitized gabbro are all fairly dry. A large pressure difference of 〉2 GPa between the metagabbro and the coesite-bearing eclogite about 20 m apart cannot be explained by the subduction hypothesis because this would require a depth difference of 〉60 km. The microlites and crystallites are evidence for rapid crystallization due to rapid cooling because constitutional supercooling was unlikely for the plagioclase pseudomorphs. Therefore, the eclogitization of the wallrock to a eclogite breccia was also coseismic, as proposed earlier for the eclogite-facies fault rocks. The lack of annealing of the broken biotite and augite overgrown by strain free skeletal garnet is consistent with a transient high- P-T event at a low ambient temperature (〈300 °C), probably in the crust. The outcrop-scale P-T variation and the transient nature of the high- P-T event are inconsistent with the existing tectonic models for high-pressure metamorphism. The fact that the less refractory, but denser biotite, is largely preserved while the more refractory but less dense plagioclase broke down completely into high-pressure microlite assemblages in the metagabbro indicates a significant rise in pressure rather than temperature. Given that the metamorphic temperatures are far below the melting temperatures of most of the gabbroic minerals under fluid-absent conditions, stress-induced amorphization appears to be the more likely mechanism of the coseismic high-pressure metamorphism. This article is protected by copyright. All rights reserved.

Description: A packed-bed reactor was established to study the effect of temperature on the controlled air oxidation (CAO) performance of a mixture of polypropylene and sawdust at a fixed feed gas flow rate. The reactor temperature was varied from 400 to 800 °C. Attention was focused on product distribution, compositions of liquid and gas products, and technical parameters. The chemical composition of the liquid products was analyzed by gas chromatography/mass spectrometry. The results indicated an obvious impact of the temperature on the described parameters. The increase in temperature led to the decrease in solid fraction and a convex shape curve for the gas yield as well as to a decrease of alkanes and alkenes, and favored the generation of oxygen-containing hydrocarbons. According to criteria of CAO conversion, the optimum temperature in the primary chamber was found to be 700 °C. A mixture of polypropy-lene and sawdust was chosen to study the effects of temperature on the oxidation performance of simulated medical waste in a packed-bed reactor. Detailed information in terms of product yields, compositions of liquid and gas products, and technical parameters is provided for a better understanding of the controlled air oxidation process.

Description: [1]  We present a statistical analysis of the occurrence probability of equatorial spread F irregularities measured by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite during 2008-2012. We use different criteria (plasma density perturbations, Δ N , and relative density perturbations, ΔN / N 0 ) to identify the occurrence of ionospheric irregularities. The purpose of this study is to determine whether the occurrence probability of irregularities is the same for different criteria, whether the patterns of irregularity occurrence vary with solar activity and with local time, and how the patterns of irregularity occurrence are correlated with ionospheric scintillation. It is found that the occurrence probability of irregularities and its variation with local time are significantly different when different identification criteria are used. The occurrence probability based on plasma density perturbations is high in the evening sector and becomes much lower after midnight. In contrast, the occurrence probability based on relative density perturbations is low in the evening sector but becomes very high at all longitudes after midnight in the June solstice. We have also compared the occurrence of ionospheric irregularities with scintillation. The occurrence pattern of the S4 index and its variation with local time are in good agreement with the irregularity occurrence based on plasma density perturbations but are significantly different from those based on relative density perturbations. This study reveals that the longitude-month pattern of the occurrence probability of equatorial ionospheric irregularities varies with local time and that only the occurrence probability of irregularities based on plasma density perturbations is consistent with the occurrence of scintillation at all local times.