ALBERT

Description: Soil moisture content is one of the most important parameters as input conditions in forecasting model systems of dust storm, but it can not be directly obtained from daily routine weather report. In this paper, a scheme is developed to calculate the surface soil moisture content in China by using both precipitation and evaporation. Precipitation is directly from routine weather report, while evaporation is indirectly calculated by using meteorological elements which are also from routine weather report. According to the formula by Penman, evaporation can be considered as a linear composition of dynamic evaporation and thermodynamic evaporation caused by radiation. First, an equation for calculating daily global radiation within China is given by using regression analysis and the data of global radiation and cloud cover from 116 meteorological stations in China. Then, an equation for calculating evaporation within China is given by using regression analysis and the data of cloud cover, air temperature, precipitation, relative humidity, and wind velocity from 701 meteorological stations. Finally, a scheme for calculating soil moisture content within China is established by using regression analysis and the soil moisture content, precipitation, and evaporation at 79 agro-meteorological stations. Validation results show that the forecasting accuracy of the Chinese dust numerical model can be clearly increased by using this scheme.

Description: Soil moisture content is one of the most important parameters as input conditions in forecasting model systems of dust storm, but it can not be directly obtained from daily routine weather report. In this paper, a scheme is developed to calculate the surface soil moisture content in China by using both precipitation and evaporation. Precipitation is directly from routine weather report, while evaporation is indirectly calculated by using meteorological elements which are also from routine weather report. According to the formula by Penman, evaporation can be considered as a linear composition of dynamic evaporation and thermodynamic evaporation caused by radiation. First, an equation for calculating daily global radiation within China is given by using regression analysis and the data of global radiation and cloud cover from 116 meteorological stations in China. Then, an equation for calculating evaporation within China is given by using regression analysis and the data of cloud cover, air temperature, precipitation, relative humidity, and wind velocity from 701 meteorological stations. Finally, a scheme for calculating soil moisture content within China is established by using regression analysis and the soil moisture content, precipitation, and evaporation at 79 agro-meteorological stations. Validation results show that the forecasting accuracy of the Chinese dust numerical model can be improved by using this scheme.

Description: Heterogeneous processes on dust particles are important for understanding the chemistry and radiative balance of the atmosphere. This paper investigates an intense Asian dust storm episode observed at Mount Heng (1269 m a.s.l.) in southern China on 24–26 April 2009. A set of aerosol and trace gas data collected during the study was analyzed to investigate their chemical evolution and heterogeneous photochemistry as the dust traveled to southern China. Results show that the mineral dust arriving at Mt. Heng experienced significant modifications during transport, with large enrichments in secondary species (sulfate, nitrate, and ammonium) compared with the dust composition collected at an upwind mountain top site (Mount Hua). A photochemical age "clock" (−Log10(NOx/NOy)) was employed to quantify the atmospheric processing time. The result indicates an obvious increase in the abundance of secondary water-soluble ions in dust particles with the air mass atmospheric processing time. Based on the observations, a 4-stage evolution process is proposed for carbonate-containing Asian dust, starting from fresh dust to particles coated with hydrophilic and acidic materials. Daytime-enhanced nitrite formation on the dust particles was also observed, which indicates the recent laboratory result of the TiO2 photocatalysis of NO2 as a potential source of nitrite and nitrous acid.

Description: Growing evidence suggests that the size-resolved mixing state of carbon-containing particles is very critical in determining their optical properties, atmospheric lifetime, and impact on the environment. However, still little is known about the mixing state of particles in the urban area of the Pearl River Delta (PRD) region, China. To investigate the mixing state of submicron carbon-containing particles, measurements were carried out during spring and fall periods of 2010 using a single-particle aerosol mass spectrometer (SPAMS). Approximately 700 000 particles for each period were detected. This is the first report on the size-resolved mixing state of carbon-containing particles by direct observations in the PRD region. Cluster analysis of single-particle mass spectra was applied to identify carbon-containing particle classes. These classes represented ~80% and ~90% of all the detected particles for spring and fall periods, respectively. Carbon-containing particle classes mainly consisted of biomass/biofuel burning particles (Biomass), organic carbon (OC), fresh elemental carbon (EC-fresh), internally mixed OC and EC (ECOC), internally mixed EC with sulfate (EC-Sulfate), vanadium-containing ECOC (V-ECOC), and amines-containing particles (Amine). In spring, the top three ranked carbon-containing particle classes were ECOC (26.1%), Biomass (23.6%) and OC (10%), respectively. However, the fraction of Biomass particles increased remarkably and predominated (61.0%), while the fraction of ECOC (3.0%) and V-ECOC (0.1%) significantly decreased in fall. To highlight the influence of monsoon on the properties of carbon-containing particles in urban Guangzhou, their size distributions, mixing state, and aerosol acidity were compared between spring and fall seasons. In addition, a case study was also performed to investigate how the formation of fog and haze influenced the mixing state of carbon-containing particles. These results could improve our understanding of the mixing state of carbon-containing particles, and may also be helpful in modeling the climate forcing of aerosol in the PRD region.

Description: The Tropical Niche Conservatism Hypothesis (TCH) tries to explain the generally observed latitudinal gradient of increasing species diversity towards the tropics. To date, few studies have used phylogenetic approaches to assess its validity, even though such methods are especially suited to detect changes in niche structure. We test the TCH using modeled distributions of 1898 woody species in Yunnan Province (southwest China) in combination with a family level phylogeny. Unlike predicted, species richness and phylogenetic diversity did not show a latitudinal gradient, but identified two high diversity zones, one in Northwest and one in South Yunnan. Despite this, the underlying residual phylogenetic diversity showed a clear decline away from the tropics, while the species composition became progressingly more phylogenetically clustered towards the North. These latitudinal changes were strongly associated with more extreme temperature variability and declining precipitation and soil water availability, especially during the dry season. Our results suggests that the climatically more extreme conditions outside the tropics require adaptations for successful colonization, most likely related to the plant hydraulic system, that have been acquired by only a limited number of phylogenetically closely related plant lineages. We emphasize the importance of phylogenetic approaches for testing the TCH.

Description: A scientific borehole, CO2W55, was drilled into an onshore anticline, near the town of Green River, Utah for the purposes of studying a series of natural CO2 reservoirs. The objective of this research project is to recover core and fluids from natural CO2 accumulations in order to study and understand the long-term consequences of exposure of supercritical CO2, CO2-gas and CO2-charged fluids on geological materials. This will improve our ability to predict the security of future geological CO2 storage sites and the behaviour of CO2 during migration through the overburden. The Green River anticline is thought to contain supercritical reservoirs of CO2 in Permian sandstone and Mississippian-Pennsylvanian carbonate and evaporite formations at depths 〉 800 m. Migration of CO2 and CO2-charged brine from these deep formations, through the damage zone of two major normal faults in the overburden, feeds a stacked series of shallow reservoirs in Jurassic sandstones from 500 m depth to near surface. The drill-hole was spudded into the footwall of the Little Grand Wash normal fault at the apex of the Green River anticline, near the site of Crystal Geyser, a CO2-driven cold water geyser. The hole was drilled using a CS4002 Truck Mounted Core Drill to a total depth of 322 m and DOSECC’s hybrid coring system was used to continuously recover core. CO2-charged fluids were first encountered at ~ 35 m depth, in the basal sandstones of the Entrada Sandstone, which is open to surface, the fluids being effectively sealed by thin siltstone layers within the sandstone unit. The well penetrated a ~ 17 m thick fault zone within the Carmel Formation, the footwall damage zone of which hosted CO2-charged fluids in open fractures. CO2-rich fluids were encountered throughout the thickness of the Navajo Sandstone. The originally red sandstone and siltstone units, where they are in contact with the CO2-charged fluids, have been bleached by dissolution of hematite grain coatings. Fluid samples were collected from the Navajo Sandstone at formation pressures using a positive displacement wireline sampler, and fluid CO2 content and pH were measured at surface using high pressure apparatus. The results from the fluid sampling show that the Navajo Sandstone is being fed by active inflow of CO2-saturated brines through the fault damage zone; that these brines mix with meteoric fluid flowing laterally into the fault zone; and that the downhole fluid sampling whilst drilling successfully captures this dynamic process.

Description: Studies on the formation of the ancient Diexi barrier lake on the Mingjiang River, southwest China, have long been carried out. However, investigations into the correlation between the paleoclimate and paleoenvironment and the paleoseismic events in this area are rarely found in literature. The present study took sediments from the ancient Diexi barrier lake to investigate the paleoclimate, paleoenvironment and paleoseismic events. A drilling at the center of the barrier lake was conducted and the core of about 260 m long was examined. The paleoclimate and paleoenviornment indicators (sporo-pollen, carbon and oxygen isotope, organic matter, calcium carbonate, granularity) from the sediments have been tested and analyzed, which indicate that there were ten climatic and environmental periods in between 30 000 a BP and 15 000 a BP. The discovered disturbance segments in the core indicate there were at least ten seismic events during that period. The consistency between climate change and seismic event indicates that a strong seismicity is normally accompanied by a climatic variation. This may be a useful supplement for the climate and geohazard prediction for the future.

Description: We use a novel statistical approach-MGPD to analyze the joint probability distribution of storm surge events at two sites and present a warning method for storm surges at two adjacent positions in Beibu Gulf, using the sufficiently long field data on surge levels at two sites. The methodology also develops the procedure of application of MGPD, which includes joint threshold and Monte Carlo simulation, to handle multivariate extreme values analysis. By comparing the simulation result with analytic solution, it is shown that the relative error of the Monte Carlo simulation is less than 8.6 %. By running MGPD model based on long data at Beihai and Dongfang, the simulated potential surge results can be employed in storm surge warnings of Beihai and joint extreme water level predictions of two sites.

Description: Studies on the formation of the ancient Diexi barrier lake on the Mingjiang River, southwestern China, have long been carried out. However, investigations into the correlation between the palaeoclimate and palaeoenvironment and the palaeoseismic events in this area are rarely found in literature. The present study took sediments from the ancient Diexi barrier lake to investigate the palaeoclimate, palaeoenvironment and palaeoseismic events. A drilling at the centre of the barrier lake was conducted and the core of about 260 m long was examined. The palaeoclimate and palaeoenvironment indicators (sporopollen, carbon and oxygen isotopes, organic matter, calcium carbonate, granularity) from the sediments have been tested and analysed, and indicate that there were 10 climatic and environmental periods between 30 000 and 15 000 a BP (before present). The discovered disturbance segments in the core indicate there were at least 10 seismic events during that period. The consistency between climate change and seismic events indicates that a strong seismicity is normally accompanied by a climatic variation. This may be a useful supplement for climate and geohazard predictions in the future.

Description: Based on a controlled laboratory experiment, numerical simulations of micro-tidal and meso-tidal conditions simulate the initiation and long-term evolution of back-barrier tidal networks. The simulated pattern formation is comparable to the morphological growth observed in the laboratory which is characterised by relatively rapid initiation and slower adjustment towards an equilibrium state. The simulated velocity field is in agreement with natural reference systems such as the micro-tidal Venice Lagoon and the meso-tidal Wadden Sea. Special attention is given to the concept of drainage density which is measured on the basis of the exceedance probability distribution of the unchannelled flow lengths. Model results indicate that the exceedance probability distribution is characterised by an approximately exponential trend, similar to the results of laboratory experiments and observations in natural systems. The drainage density increases greatly during the initial phase of tidal network development while it slows down when the system approaches equilibrium. Due to the larger tidal prism, the tidal basin has a larger drainage density for the meso-tidal condition (after the same amount of time) than the micro-tidal case. In both micro-tidal and meso-tidal simulations, it is found that there is an initial rapid increase of the tidal prism which soon reaches a relatively steady value (after approximately 40 yr) while the drainage density adjusts more slowly. In agreement with the laboratory experiments, the initial bottom perturbations play an important role in determining the morphological development and hence the exceedance probability distribution of the unchannelled flow lengths. Overall, our study indicates an agreement between the numerical and experimental tidal networks on the geometric characteristics.