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Numerical Simulation of Fluxes Generated by Inhomogeneities of the Underlying Surface over the Jinta Oasis in Northwestern China

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Advances in Atmospheric Sciences 2011年第4期28卷 887-906页

作者：李万莉吕世华傅慎明孟宪红 H.C.NNAMCHI Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences Institute of Atmospheric Physics Chinese Academy of Sciences Department of Geography University of Nigeria

Using land-use types derived from satellite remote sensing data collected by the EOS Moderate Resolution Imaging Spectroradiometer （EOS/MODIS）, the mesoscale and turbulent fluxes generated by inhomogeneities of the underlying surface over the Jinta Oasis, northwestern China, were simulated using the Regional Atmospheric Modeling System （RAMS4.4）. The results indicate that mesoscale circulation generated by land-surface inhomogeneities over the Jinta Oasis is more important than turbulence. Vertical heat fluxes and water vapor are transported to higher levels by mesoscale circulation. Mesoscale circulation also produces mesoscale synoptic systems and prevents water vapor over the oasis from running off. Mesoscale circulation transports moisture to higher atmospheric levels as the land-surface moisture over the oasis increases, favoring the formation of clouds, which sometimes leads to rainfall. Large-scale wind speed has a significant impact on mesoscale heat fluxes. During the active phase of mesoscale circulation, the stronger large-scale winds are associated with small mesoscale fluxes; however, background wind seems to intensify the turbulent sensible heat flux and turbulent latent heat flux. If the area of oasis is enlarged properly, mesoscale circulation will be able to transport moisture to higher levels, favoring the formation of rainfall in the oasis and protecting its ＂cold island＂ effect. The impact of irrigation on rainfall is important, and increasing irrigation across the oasis is necessary to protect the oasis.

关键词： inhomogeneities RAMS mesoscale circulation turbulence heat flux

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On the Relationship between Climatic Variables and Pressure Systems over Saudi Arabia in the Winter Season

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Advances in Atmospheric Sciences 2015年第5期32卷 690-703页

作者： H.M.HASANEAN H.Abdel BASSET M.A.A.HUSSEIN Department of Meteorology Faculty of Meteorology Environment and Arid Land AgricultureKing Abdulaziz University Department of Meteorology and Astronomy Faculty of Science Al-Azhar University

The synoptic circulation over Saudi Arabia is complicated and frequently governed by the effect of large-scale pressure systems. In this work, we used NCEP–NCAR global data to illustrate the relationship between climatic variables and the main pressure systems that affect the weather and climate of Saudi Arabia, and also to investigate the influence of these pressure systems on surface air temperature（SAT） and rainfall over the region in the winter season. It was found that there are two primary patterns of pressure that influence the weather and climate of Saudi Arabia. The first occurs in cases of a strengthening Subtropical High（Sub H）, a weakening Siberian High（Sib H）, a deepening of the Icelandic Low（Ice L）, or a weakening of the Sudanese Low（Sud L）. During this pattern, the Sub H combines with the Sib H and an obvious increase of sea level pressure（SLP） occurs over southern European, the Mediterranean, North Africa, and the Middle East. This belt of high pressure prevents interaction between midlatitude and extratropical systems, which leads to a decrease in the SAT,relative humidity（RH） and rainfall over Saudi Arabia. The second pattern occurs in association with a weakening of the Sub H, a strengthening of the Sib H, a weakening of the Ice L, or a deepening of the Sud L. The pattern arising in this case leads to an interaction between two different air masses： the first（cold moist） air mass is associated with the Mediterranean depression travelling from west to east, while the second（warm moist） air mass is associated with the northward oscillation of the Sud L and its inverted V-shape trough. The interaction between these two air masses increases the SAT, RH and the probability of rainfall over Saudi Arabia, especially over the northwest and northeast regions.

关键词： climatic variables pressure system surface air temperature rainfall relative humidity Saudi Arabia

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Evaluation of the WRF-Lake Model over Two Major Freshwater Lakes in China

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Journal of Meteorological Research 2019年第2期33卷 219-235页

作者： Yuanyuan MA Yi YANG Chongjian QIU Chenghai WANG Key Laboratory for Semi-arid Climate Change of the Ministry of Education College of Atmospheric SciencesLanzhou University Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences

This paper evaluates the performance of the Weather Research and Forecasting(WRF) model coupled with a lake scheme over the Lake Poyang and Lake Dongting regions. We choose several cases with different weather characteristics, including winter with/without precipitation and summer with/without precipitation, and conduct a series of experiments(without the lake model, with the default lake model, and with a calibrated lake model that adjusts the water absorption, extinction coefficients, and surface roughness length) for each case. The results show that the performance of the lake model is significantly affected by the weather conditions. For the winter with precipitation cases, the performance of the default lake model is even worse than without the lake model, but the calibrated lake model can obviously reduce the biases of 2-m temperature and dew-point temperature. Although the performance of the default and new calibrated models is intricate for other cases, the new calibrated model has prominent advantages for 2-m dew-point temperature. Moreover, a long-term simulation of five months also shows that the new calibrated coupled lake model performs better than the default one. These imply that the new calibrated coupled lake model is more suitable to be used in studies of the effects of Lake Poyang and Lake Dongting on regional weather and climate.

关键词： atmosphere-lake coupled model Lake Poyang Lake Dongting calibration weather characteristics

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Effect of rangeland rehabilitation on the herbaceous species composition and diversity in Suswa catchment,Narok County,Kenya

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Ecological Processes 2017年第1期6卷 427-435页

作者： N.J.Ombega S.M.Mureithi O.K.Koech A.N.Karuma C.K.K.Gachene Department of land Resource management and Agricultural Technology(LARMAT) University of NairobiP.O Box 29053Nairobi 00625Kenya Sustainable land management(SLM)Agro-Pastoral Project Kenya NairobiKenya

Introduction:land degradation is a serious environmental problem of our *** Kenya,it is estimated that 30%of the total land mass is severely *** catchment within Narok County is a good example with gullies of over 25 m deep and 30 m *** response to the increasing land degradation in the area,the Sustainable land management(SLM)project rehabilitated the catchment through establishment of soil and water conservation structures such as cutoff drains,semicircular bunds,and water retention *** the various rehabilitation approaches carried out,little research has been done to ascertain their effect on successful vegetation *** coupled with the fact that many restoration approaches have failed in East Africa and Kenya in particular gave drive to the *** objective of this study was to determine the effects of rangeland rehabilitation on herbaceous species composition and diversity in a severely degraded ***:To assess the diversity of aboveground herbaceous layer in the rehabilitated and degraded areas along a slope(upper,middle,and lower),line transect and quadrat count methods were *** each slope position,three 100-m-long transects were placed across the hill parallel to one another 30 m apart using a *** species hit,the closest species to the hit,and hits on bare ground were *** the same transects,1-m2 quadrats were placed 25 m apart and aboveground biomass determined by the use of the destructive *** the determination of species richness,diversity,relative abundance,percentage cover,and species composition,the Shannon-Wiener diversity index was *** collected on vegetation attributes was subjected to analysis of variance(ANOVA)using Genstat and Tukey’s HSD post hoc used in means separation where F values were ***:The results showed that percent cover(74.67%),aboveground biomass(1459 kg/ha),relative abundance,richness,composition,and diversity of perennial grass

关键词： Rehabilitation land degradation Slope,Herbaceous layer Biodiversity

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Legume green manure can intensify the function of chemical nitrogen fertilizer substitution via increasing nitrogen supply and uptake of wheat

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The Crop Journal 2024年第4期12卷 1222-1232页

作者： Jingui Wei Zhilong Fan Falong Hu Shoufa Mao Fang Yin Qiming Wang Qiang Chai Wen Yin State Key Laboratory of arid land Crop Science Lanzhou 730070GansuChina College of Agronomy Gansu Agricultural UniversityLanzhou 730070GansuChina

Achieving the green development of agriculture requires the reduction of chemical nitrogen(N)fertilizer *** studies have confirmed that returning green manure to the field is an effective measure to improve crop yields while substituting partial chemical N ***,it remains unclear how to further intensify the substituting function of green manure and elucidate its underlying agronomic *** a split-plot field experiment in spring wheat,different green manures returned to the field under reduced chemical N supply was established in an oasis area since 2018,in order to investigate the effect of green manure and reduced N on grain yield,N uptake,N use efficiency(NUE),N nutrition index,soil organic matter,and soil N of wheat in *** results showed that mixed sown common vetch and hairy vetch can substitute 40%of chemical N fertilizer without reducing grain yield or N ***,mixed sown common vetch and hairy vetch under reduced N by 20%showed the highest N agronomy efficiency and recovery efficiency,which were 92.0%and 46.0%higher than fallow after wheat harvest and conventional N application rate,*** increase in NUE of wheat was mainly attributed to mixed sown common vetch and hairy vetch,which increased N transportation quantity and transportation rate at pre-anthesis,enhanced N harvest index,optimized N nutrition index,and increased activities of nitrate reductase and glutamine synthetase of leaf,***,mixed sown common vetch and hairy vetch under reduced N by 20%improved soil organic matter and N ***,mixed sown common vetch and hairy vetch can substitute 40%of chemical N fertilizer while maintaining grain yield and N accumulation,and it combined with reduced chemical N by 20%or 40%improved NUE of wheat via enhancing N supply and uptake.

关键词： Legume green manure Reduced N input Wheat N uptake and supply Agronomic mechanism

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Species composition,distribution patterns and ecological functions of biological soil crusts in the Gurbantunggut Desert

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Journal of arid land 2010年第3期2卷 180-189页

作者： Zhang, YuanMing Wu, Nan Zhang, BingChang Zhang, Jing Chinese Acad Sci Xinjiang Inst Ecol & Geog Key Lab Biogeog & Bioresource Arid Land Urumqi 830011 Peoples R China

As one of the most important biological factors that maintain the stability of the largest fixed and semi-fixed desert in China,the Gurbantunggut Desert,the biological soil crusts (BSCs) develop well and play critical ecological roles in the desert ecosystem. In this paper,we briefly summarize our research findings since 2002 including species composition,distribution pattern and ecological functions of BSCs in the desert. Our results indicate abundant species diversity of BSCs in the Gurbantunggut Desert in comparison to other deserts in China. At the scales of sand dune or whole desert,the distribution patterns of BSCs are location-specific. The existence of BSCs in this desert could:(1) accelerate the formation of desert soil and the weathering of minerals; (2) accumulate organic matter in surface soil through related species in soil crusts; (3) enhance the abilities of sand surface to resist wind erosion; (4) influence seed germination of vascular plants; and (5) enhance the production of dew deposition on sandy soil surface.

关键词： biological soil crusts species diversity location-specific distribution desert ecosystem

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Research progress and developing trends on microorganisms of Xinjiang specific environments

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Journal of arid land 2010年第1期2卷 51-56页

作者： Pan, HuiXia Cheng, ZhengMing Zhang, YuanMing Mu, ShuYong Qi, XiaoLing Chinese Acad Sci Key Lab Biogeog & Bioresource Arid Land Xinjiang Inst Ecol & Geog Urumqi 830011 Peoples R China

Microorganisms and its metabolic types are diverse in Xinjiang because of those extreme/special environments of drought, high or low temperature, saline and alkaline, oligotrophy. This article reviewed the research progress and achievements of various microbial resources (bacteria, fungi and actinomycete) in the special environments from the point of its ecology, development and application. Meanwhile, the development trend, protection and sustainable utilization of the microorganism resources were discussed.

关键词： Xinjiang microorganism special environment research progress trend development

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The Dynamic Plateau Monsoon Index and Its Association with General Circulation Anomalies

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Advances in Atmospheric Sciences 2012年第6期29卷 1249-1263页

作者：荀学义胡泽勇马耀明 Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences Inner Mongolia Autonomous Region Meteorological Observatory Institute of Tibetan Plateau Research Chinese Academy of Sciences

Based on monthly ECMWF reanalysis-Interim （ERA-Interim） reanalysis data, along with monthly precipitation and temperature data, the Dynamic Plateau Monsoon Index （DPMI） is defined. The results of a contrast analysis of the DPMI versus the Traditional Plateau Monsoon Index （TPMI） are described. The response of general circulation to northern Qinghai-Xizang Plateau summer monsoon anomalies and the correlation of the DPMI with general circulation anomalies are investigated. The results show that, the DPMI reflected meteorological elements better and depicted climate variation more accurately than the TPMI. In years when the plateau summer monsoon is strong, the low over the plateau and the trough near the eastern coast of Asia are deeper and higher than normal over South China. This correlation corresponds to two anomalous cyclones over the plateau and the eastern coast of Asia and an anomalous anticyclone in South China. The plateau and its adjacent regions are affected by anomalous southwesterly winds that transport more moisture to South China and cause more precipitation. The lower reaches of the Yangtze River appear to receive more precipitation by means of the strong westerly water vapor flow transported from the ＂large triangle affecting the region＂. In years when the plateau summer monsoon is weak, these are opposite. The plateau monsoon is closely related to the intensity and position of the South Asian high, and the existence of a teleconnection pattern in the mid-upper levels suggests a possible linkage of the East Asian monsoon and the Indian monsoon to the plateau summer monsoon.

关键词： Qinghai-Xizang Plateau Dynamic Plateau Monsoon Index center position general circulation

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Estimation of Turbulent Fluxes Using the Flux-Variance Method over an Alpine Meadow Surface in the Eastern Tibetan Plateau

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Advances in Atmospheric Sciences 2013年第2期30卷 411-424页

作者： WANG Shaoying ZHANG Yu LU Shihua LIU Heping SHANG Lunyu Key Laboratory of land Surface and Climate Change in Cold and arid Regions Cold and Arid RegionsEnvironmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 Laboratory for Atmospheric Research Department of Civil and Environmental Engineering Washington State University Pullman WA

The flux-variance similarity relation and the vertical transfer of scalars exhibit dissimilarity over different types of surfaces, resulting in different parameterization approaches of relative transport efficiency among scalars to estimate turbulent fluxes using the flux-variance method. We investigated these issues using eddycovariance measurements over an open, homogeneous and flat grassland in the eastern Tibetan Plateau in summer under intermediate hydrological conditions during rainy season. In unstable conditions, the temperature, water vapor, and CO2 followed the flux-variance similarity relation, but did not show in precisely the same way due to different roles （active or passive） of these scalars. Similarity constants of temperature, water vapor and CO2 were found to be 1.12, 1.19 and 1.17, respectively. Heat transportation was more eft% cient than water vapor and CO2. Based on the estimated sensible heat flux, five parameterization methods of relative transport efficiency of heat to water vapor and CO2 were examined to estimate latent heat and CO2 fluxes. The strategy of local determination of flux-variance similarity relation is recommended for the estimation of latent heat and CO2 fluxes. This approach is better for representing the averaged relative transport efficiency, and technically easier to apply, compared to other more complex ones.

关键词： flux-variance method relative transfer efficiency eddy-covariance method homogeneous landsurface turbulent flux

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Influence of advection on the characteristics of turbulence over uneven surface in the oasis and the Gobi Desert

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Science China Earth Sciences 2014年第11期57卷 2242-2258页

作者： CHEN JinBei HU YinQiao Lü ShiHua YU Ye Key Laboratory of land Surface Process and Climate Change in Cold and arid Regions Cold and arid Regions Environment and Engineering Institute Chinese Academy of Sciences

Utilizing experimental data of the atmospheric surface layer in the Gobi Oasis of Jinta in a comparative study, we demonstrate that under the condition of unstable stratification, the normalization variances of temperature in the oasis and Gobi Desert meetφs （z∧）= φθ（Z/∧） =αθ（-Z/ ∧）-1/3 while normalization variances of both humidity and CO2 in the oasis meet φ（Z/∧）= αs （1 - βs z /∧）-1/3 ; the normalization variance of temperature in the oasis is large due to disturbance by advection, whereas variance of CO2 in the Gobi Desert has certain degree of deviation relative to Monin-Obukhov （M-O） scaling, and humidity variance completely deviates from variance M-O scaling. The above result indicates that under the condition of advection, hu-midity variance meets the relation δ2 sm=D2 δ2SA ＋ δ2SB and it is determined by relative magnitude of scalar variance of ad- midity variance meets the relation δsm = D2δsA ＋ δsB vection transport. Our study reveals that, if the scalar variance of humidity or CO2 transported by advection is much larger than local scalar variance, observation value of scalar variance will deviate from M-O scaling; when scalar variance of advection transport is close to or less than local scalar variance, the observation value of scalar variance approximately meets M-O scal- ing.

关键词： atmospheric surface layer (ASL) turbulence similarity theory advection uneven surface

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