Analysis of the Microphysical Properties of a Stratiform Rain Event Using an L-Band Profiler Radar   总被引：2，自引：0，他引：2       下载免费PDF全文

RUAN Zheng  MING Hu  MA Jianli  GE Runsheng  BIAN Lingen 《Acta Meteorologica Sinica》2014,28(2):268-280

This paper investigates spatial and temporal distributions of the microphysical properties of precipitating stratiform clouds based on Doppler spectra of rain particles observed by an L-band profiler radar.The retrieval of raindrop size distributions（RSDs） is accomplished through eliminating vertical air motion and isolating the terminal fall velocity of raindrops in the observed Doppler velocity spectrum.The microphysical properties of raindrops in a broad stratiform region with weak convective cells are studied using data collected from a 1320-MHz wind profiler radar in Huayin,Shaanxi Province on 14 May 2009.RSDs and gamma function parameters are retrieved at altitudes between 700 and 3000 m above the surface,below a melting layer.It is found that the altitude of the maximum number of raindrops was closely related to the surface rain rate.The maximum number of large drops was observed at lower altitudes earlier in the precipitation event but at higher altitudes in later periods,suggesting decreases in the numbers of large and medium size raindrops.These decreases may have been caused by the breakup of larger drops and evaporation of smaller drops as they fell.The number of medium size drops decreased with increasing altitude.The relationship between reflectivity and liquid water content during this precipitation event was Z = 1.69×10~4M~（1.5）,and the relationship between reflectivity and rain intensity was Z = 256I~（1.4）.  相似文献   

The Response of First Flowering Dates to Abrupt Climate Change in Beijing   总被引：1，自引：0，他引：1  

BAI Jie  GE Quansheng  DAI Junhu 《大气科学进展》2011,28(3):564-572

Phenological data on the First Flowering Date(FFD) of woody plants in Beijing from 1963-2007 are analyzed.The correlation between each species’ yearly FFD and the mean monthly temperatures for every year over a 45-year period is used to identify the month in which temperature has the most effect on FFD. Through further analysis,the FFDs of 48 woody plant species are shown to have advanced an average of 5.4 days from 1990-2007 compared to 1963-1989.The results indicate that 70.8%of species flowered significantly earlier(7 days on average) during the period 1990-2007,while only one species(2.1%) flowered significantly later.Moreover,the responses of FFD to climate change are shown to be different in two climatic stages, defined by an abrupt climate change point.Thirty-three species which first flower in March and April are sensitive to temperature are examined.The correlation coefficients between FFD and temperature for 20 species during the latter period(1990-2007) are shown to be larger than during the former period(1963- 1989),with a difference of around -0.87 days per 1℃on average.The paper concludes that with the warming of climate,the linear trend of FFD variation,as well as its responsiveness to temperature,became more prominent during 1990-2007 than 1963-1989.The data analyzed in this study present a strong biological indicator of climate change in Beijing,and provide further confirmation of previous results from regional and local studies across the Northern Hemisphere.Phenophase variations indicate that the climate is changing rapidly.  相似文献   

Wave-Enhanced Sediment-Gravity Flows in Bohai Bay Lacustrine Basin, Eastern China     

BAI Chenyang  YU Bingsong  DONG Tianyang  HAN Shujun  GE Ji  ZHU Donglin 《《地质学报》英文版》2018,92(6):2416-2431

Sequences of wave-enhanced sediment-gravity flows (WESGFs) have been widely recognized in the marine shelf environment. In this study, we show observations of WESGF deposits in lacustrine settings using well core and thin section data from the Paleogene in the Jiyang sub-basin, Bohai Bay basin, eastern China. The findings of this study include the following: 1) the sequence of WESGFs in the lacustrine basin is similar to that of marine; it consists of three units, MF1 unit: siltstone with basal erosion surface, MF2 unit: silt-streaked claystone, and MF3 unit: silty-mudstone; and 2) prodelta sand sheets are found in the lacustrine WESGF sequence and are classified as the MFd unit: clay-streaked siltstone. However, because the system size and variability in hydrodynamic conditions are different between the lacustrine and marine basins, lacustrine WESGFs do appear to have three distinguishable features: 1) the sediment grain size and sand content are slightly higher than those of the marine WESGFs; 2) lacustrine WESGFs may contain prodelta sediments or sedimentary sequences of other types of gravity flows, such as hyperpycnal flows; and 3) the scale of the sedimentary structures for lacustrine WESGFs is smaller. The WESGFs found in the continental lacustrine basin provide a new model for sediment dispersal processes in lake environments and may be helpful to explain and predict the distribution of sandy reservoirs for oil and gas exploration.  相似文献   

A method to estimate concentrations of surface-level particulate matter using satellite-based aerosol optical thickness   总被引：3，自引：0，他引：3  

TAO JinHua  ZHANG MeiGen  CHEN LiangFu  WANG ZiFeng  SU Lin  GE Cui  HAN Xiao  ZOU MingMin 《中国科学:地球科学(英文版)》2013,(8):1422-1433

We propose a new method to estimate surface-level particulate matter(PM)concentrations by using satellite-retrieved Aerosol Optical Thickness(AOT).This method considers the distribution and variation of Planetary Boundary Layer(PBL)height and relative humidity(RH)at the regional scale.The method estimates surface-level particulate matter concentrations using the data simulated by an atmospheric boundary layer model RAMS and satellite-retrieved AOT.By incorporation MODIS AOT,PBL height and RH simulated by RAMS,this method is applied to estimate the surface-level PM 2.5 concentrations in North China region.The result is evaluated by using 16 ground-based observations deployed in the research region,and the result shows a good agreement between estimated PM 2.5 concentrations and observations,and the coefficient of determination R2 is 0.61 between the estimated PM 2.5 concentrations and the observations.In addition,surface-level PM 2.5 concentrations are also estimated by using MODIS AOT,ground-based LIDAR observations and RH measurements.A comparison between the two estimated PM 2.5 concentrations shows that the new method proposed in this paper is better than the traditional method.The coefficient of determination R2 is improved from 0.32 to 0.62.  相似文献   

CLDASSD: Reconstructing Fine Textures of the Temperature Field Using Super-Resolution Technology     

Ruian TIE  Chunxiang SHI  Gang WAN  Xingjie HU  Lihua KANG  Lingling GE 《大气科学进展》2022,39(1):117-130

Before 2008,the number of surface observation stations in China was small.Thus,the surface observation data were too sparse to effectively support the High-resolution China Meteorological Administration’s Land Assimilation System(HRCLDAS)which ultimately inhibited the output of high-resolution and high-quality gridded products.This paper proposes a statistical downscaling model based on a deep learning algorithm in super-resolution to research the above problem.Specifically,we take temperature as an example.The model is used to downscale the 0.0625°×0.0625°,2-m temperature data from the China Meteorological Administration’s Land Data Assimilation System(CLDAS)to 0.01°×0.01°,named CLDASSD.We performed quality control on the paired data from CLDAS and HRCLDAS,using data from 2018 and 2019.CLDASSD was trained on the data from 31 March 2018 to 28 February 2019,and then tested with the remaining data.Finally,extensive experiments were conducted in the Beijing-Tianjin-Hebei region which features complex and diverse geomorphology.Taking the HRCLDAS product and surface observation data as the"true values"and comparing them with the results of bilinear interpolation,especially in complex terrain such as mountains,the root mean square error(RMSE)of the CLDASSD output can be reduced by approximately 0.1℃,and its structural similarity(SSIM)was approximately 0.2 higher.CLDASSD can estimate detailed textures,in terms of spatial distribution,with greater accuracy than bilinear interpolation and other sub-models and can perform the expected downscaling tasks.  相似文献   

Adaptive filter in SAR interferometry derived DEM   总被引：3，自引：0，他引：3  

XU Caijun WANG Hua WANG Jianglin GE Linlin 《地球空间信息科学学报》2005,8(3):193-196

IntroductionRadar interferometry (InSAR) has been suc-cessfully applied to measure the surface topogra-phyin the past two decades[1-4].Since InSARisa coherent technology ,the most i mportant con-straint for the radar echo is coherence . Howev-er ,decorrelation is al ways inevitably introducedby the thermal noise , geometric decorrelation,Doppler centroid decorrelation, volume scatter-ing decorrelation,temporal decorrelation, orbiterror , at mospheric delay , and data processingnoise[5-6]. …  相似文献   

Decision support for integrated river basin management—Scientific research challenges     

CAI XiMing  Landon MARSTON  GE YingChun 《中国科学:地球科学(英文版)》2015,(1):16-24

Integrated River Basin Management(IRBM)has been a long discussed way to sustainably manage water and land resources;yet,very few examples of effective IRBM are found because there is a lack of sufficient scientific support,as well as institutional accommodation,to successfully implement it.This paper overviews the major challenges with IRBM,the promising scientific approaches for the implementation of IRBM,and the areas of needed research,with considerable issues and experiences from China.It is expected that novel research will draw together disparate disciplines into an integrated scientific framework,upon which better modeling tools,stakeholder involvement,and decision-making support can be built.Cutting-edge new technologies will bring ideas of IRBM forward to theory and finally to practice.The paper will prompt scientists to undertake research to fill in the gaps in the current IRBM knowledge base and provide practitioners guidance on how to incorporate scientifically based information within the IRBM decision process.  相似文献   

Starch grains from dental calculus reveal ancient plant foodstuffs at Chenqimogou site, Gansu Province     

LI MingQi    YANG XiaoYan  WANG Hui  WANG Qiang  JIA Xin & GE QuanSheng Institute of Geographical Sciences  Natural Resources Research  Chinese Academy of Sciences  Beijing  China  Graduate School of the Chinese Academy of Sciences  Beijing  Gansu Provincial Institute of Cultural Relics  Archaeology  Lanzhou  Key Laboratory of Western China’s Environmental Systems  MOE  Lanzhou University 《中国科学:地球科学(英文版)》2010,(5)

Chenqimogou site, located at the south bank of Tao River, is comprised of a large group of graves dated to ~4000 a BP. For its large scale, unique mortuary system, and abundant of typical artifacts, the site was named one of Top Ten Archaeological Discoveries of 2008 in China. Many intact human skeletons have been excavated from the graves. Three teeth from two adult skeletons excavated from graves M187 and M194 were examined. Forty-eight starch grains were retrieved from dental calculus of three teeth. Six...  相似文献   

Along-track Calibration of the Zhurong Rover Magnetometer     

Hao LUO  Aimin DU  Yasong GE  Ying ZHANG  Haiying LI  Lin TIAN  Kuixiang ZHANG  Shuquan SUN  Lin ZHAO  Zhi LI  Xiao FENG 《中国科学:地球科学(英文版)》2024,(2):552-565

As part of the Chinese Tianwen-1 mission, the Zhurong Rover began its scientific investigation in the southern Utopia Planitia after its successful landing in 15 May, 2021. The Zhurong Rover magnetometer(RoMAG), one of the six payloads onboard the rover, includes two identical high-sensitivity triaxial fluxgate magnetometers and can implement mobile magnetic measurements on the surface of Mars. Although a rover magnetic compensation procedure was conducted to remove the magnetic interferences pr...  相似文献   

不列颠哥伦比亚省Harrison湖与第三纪深成作用有关的脉状金矿化     

Ray.  GE 夭华 《国外铀金地质》1993,10(3):224-231

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