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Estimating surface evapotranspiration using combined MODIS and CBERS-02 data

Science china(Technological sciences) 2005年第S2期48卷 145-160页

作者： XIN Xiaozhou1,2, LIU Qinhuo1, TANG Yong1,3, TIAN Guoliang1, GU Xingfa1, LI Xiaowen1,2, ZHENG Hongsheng4.& CHEN Jiayi4.1. State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing Applications, Chinese academy of sciences, Beijing 100101, china 2. Research Center for Remote Sensing and GIS, Department of Geography, Beijing Normal university, Beijing 100875, china 3. graduate university of Chinese academy of sciences, Beijing 100039, china 4. Department of Atmospheric Physics, Peking university, Beijing 100871, china 1. State Key Laboratory of Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences 100101 Beijing China2. Research Center for Remote Sensing and GIS Department of Geography Beijing Normal University 100875 Beijing China3. Graduate University of Chinese Academy of Sciences 100039 Beijing China4. Department of Atmospheric Physics Peking University 100871 Beijing China

Spatial scale error is one of the most serious problems in the estimates of land surface heat fluxes of sensible and latent from satellite-borne data such as MODIS 1km resolution reflectance and emissive data. One of the feasible and economic ways to decrease the spatial scale error is to use high resolution land use class data together with the MODIS data. CBERS-02 data were used to produce land use class of Baiyangdian area, Hebei Province, china in the autumn of 2004. The area ratio of each class in MODIS pixel was calculated, and used to derive the heat fluxes of the mixed pixel. The results showed that the estimated heat fluxes of soil, sensible and latent have been changed remarkably after using the high resolution land class data. It could be concluded from the comparison between simulated and ground-measured fluxes as well as the theoretical analysis that high resolution land class data are useful to diminishing the scale error of heat fluxes estimated from low resolution satellite data.

关键词： surface evapotranspiration spatial scale error MODIS CBERS land class.

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Modeling the climate effects of different subregional uplifts within the Himalaya-Tibetan Plateau on Asian summer monsoon evolution

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Chinese Science Bulletin 2012年第35期57卷 4617-4626页

作者： ZHANG Ran 1,JIANG DaBang 1,2,3,LIU XiaoDong 4.& TIAN ZhiPing 2,5 1 Climate Change Research Center,Chinese academy of sciences,Beijing 100029,china 2 Nansen-Zhu International Research Centre,Institute of Atmospheric Physics,Chinese academy of sciences,Beijing 100029,china 3 Key Laboratory of Regional Climate-Environment Research for Temperate East Asia,Chinese academy of sciences,Beijing 100029,china 4.State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese academy of sciences,Xi’an 710075,china 5 graduate university of Chinese academy of sciences,Beijing 10004.,china 1. Climate Change Research Center Chinese Academy of Sciences Beijing 100029 China 2. Nansen-Zhu International Research Centre Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China 3. Key Laboratory of Regional Climate-Environment Research for Temperate East Asia Chinese Academy of Sciences Beijing 100029 China 4. State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China 5. graduate university of Chinese academy of sciences Beijing 100049 China

Considering the different uplifting time of different subregions of the Himalaya-Tibetan Plateau(TP),a series of numerical simulations have been conducted with the Community Atmosphere Model(CAM4. developed at the National Center for Atmospheric Research to explore the effects of the phased tectonic uplift of the Himalaya-TP on the evolution of Asian summer *** results show that the uplifts of the Himalaya and northern TP significantly affect the evolutions of South Asian summer monsoon and northern East Asian summer monsoon *** is,the tectonic uplift of the Himalaya intensifies the South Asian summer monsoon circulation and increases the precipitation in South Asia,whereas the uplift of the northern TP intensifies the northern East Asian summer monsoon circulation and increases the precipitation in northern East *** with previous simulations,current comparative analyses of modeling results for different subregional uplifts within the Himalaya-TP help deepen our understanding of the evolutionary history of Asian monsoons.

关键词：青藏高原隆升喜马拉雅亚洲季风高原气候夏季季风次区域隆起演化建模

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Narrow line Seyfert 1 galaxies: where are the broad line regions?

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Science china(Physics,Mechanics & Astronomy) 2010年第12期53卷 2307-2311,2339-2343页

作者： MAO WeiMing 1,2,3 , HU Chen 2 , WANG JianMin 2 , BIAN WeiHao 4., ZHANG Shu 2 & ZHAO Gang 1 1 Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese academy of sciences, Beijing 100012, china 2 Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese academy of sciences, Beijing 10004., china 3 graduate university of the Chinese academy of sciences, Beijing 10004., china 4.Department of Physics, Nanjing Normal university, Nanjing 210011, china 1. Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China2. Key Laboratory for Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China3. Graduate University of the Chinese Academy of Sciences Beijing 100049 China4. Department of Physics Nanjing Normal University Nanjing 210011 China

A sample consisting of 211 narrow line Seyfert 1 galaxies (NLS1s) with high quality spectra from the Sloan Digital Sky Survey (SDSS) is selected to explore where broad line regions are in these objects. We find that the Hβ profile can be fitted well by three (narrow, intermediate and broad) Gaussian components, and the FWHM ratios of the broad to the intermediate components hold a constant of 3.0 roughly for the entire sample. If the broad components originate from the region scaled by the well-determined Hβ reverberation mapping relation, we find that the intermediate components originate from the inner edge of the torus, which is scaled by dust K-band reverberation. We find that the IC and the BC are strongly linked dynamically, but the relation of their covering factors is much more relaxed, implying that both regions are clumpy.

关键词： black hole physics galaxies: evolution quasars: general

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Models and methods for precise determination of ionospheric delay using GPS

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Progress in Natural Science:Materials International 2007年第2期17卷 187-196页

作者： YUAN Yunbin, HUO Xingliang and OU Jikun ( Institute of Geodesy and Geophysics, Chinese academy of sciences, Wuhan 4.0077, china graduate {4. of Chinese A-cademy of sciences, Beijing 100039, china) [a]Chinese academy of sciences Institute of Geodesy and Geophysics Wuhan China [b]graduate university of Chinese academy of sciences Beijing China

The basic principles and methods for precisely determining ionospheric delays in GPS observations are introduced and discussed. Various methods and models for fitting ionospheric delays based on GPS are compared and a... 详细信息

关键词： GPS ionospheric delay atmosphere modeling precise GPS positioning.

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The impact of vegetation restoration on erosion-induced sediment yield in the middle Yellow River and management prospect

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Science china Earth sciences 2005年第6期48卷 724-741页

作者： CHEN Hao1, ZHOU Jinxing2, CAI Qiangguo1, YUE Zhongqi3, LU Zhongchen4. LIANG Guanglin1& HUANG Jianguo5 1. Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic sciences and Natural Resources Re-search, Chinese academy of sciences, Beijing 100101, china 2. Institute of Forestry, Chinese academy of Forestry sciences, Beijing 100091, china 3. Department of Civil Engineering, university of Hong Kong, Hong Kong, china 4. Eco-environmental Research Center, Chinese academy of sciences, Beijing 100085, china 5. College of Resources and Environment, Southwest Agricultural university, Chongqing 4.0716, china Correspondence should be addressed to Chen Hao 1. Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing China 2. Institute of Forestry Chinese Academy of Forestry Sciences 100091 Beijing China 3. Department of Civil Engineering University of Hong Kong Hong Kong China 4. Eco-environmental Research Center Chinese Academy of Sciences 100085 Beijing China 5. College of Resources and Environment Southwest Agricultural University 400716 Chongqing China

According to the characteristics of water and erosion environments of different natural zones on the Loess Plateau, this paper studies changes of vegetation types, distribution boundaries of forest and grass as well as restoration capacity of vegetation in different natural zones in the middle Yellow River. The annual precipitation of 530 mm is the critical annual pre-cipitation for forest and grass distribution in the middle Yellow River. Among the zonal and azonal environmental factors affecting watershed sediment yield, the intermediate diameter D50 (mm) of suspended load and forest coverage (V, %) play the leading role. Of them the effect weight of forest coverage (V, %) on catchments sediment yield is only 3.4. less than the role of the intermediate diameter (D50, mm), they are almost the same. To effectively control soil erosion in semiarid, especially in hilly-gullied areas and make sediment transport modulus reduce to less than 6000 t/km2, it is rather difficult by merely relying on natural restoration of forest. In the process of cultivated land conversion into forest land and grassland, measures suiting local conditions should be adopted in tree species selection and artificial afforestation (grass planting) based on management with biological measures for slopeland and engineering measures for hilly-gullied areas, so that watershed forest coverage in key counties can reach at least over 30%.Compared with the standard period of precipitation prior to the 1960s, with the decrease of an-nual precipitation at various periods, plant productivities decline to different degrees under natural conditions. The main reason accountable for the low survival rate of new seedlings and grass over years is due to precipitation decrease. In light with regression models of annual pre-cipitation and natural vegetation productivities, it is possible to obtain estimated values of wa-tershed natural vegetation productivity and eco-water consumption needed for the restoration to

关键词： vegetation restoration, eco-water requirement, watershed sediment yield, the middle Yellow River.

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Spatial heterogeneity of the driving forces of cropland change in china

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Science china Earth sciences 2005年第12期48卷 2231-2240页

作者： LIU Xuhua1,2, WANG Jinfeng1, LIU Mingliang4.1 & MENG Bin1,2,3 1. Institute of Geographic sciences and Natural Resources Research, Chinese academy of sciences, Beijing 100101, china 2. {4. School of the Chinese academy of sciences, Beijing 100039, china 3. College of Arts and sciences of Beijing Union university, Beijing 100083, china 4. School of Forestry and Wildlife sciences, Auburn university, Auburn, Alabama, AL3684., USA 1. Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing China 2. graduate School of the Chinese academy of sciences 100039 Beijing China 3. School of Forestry and Wildlife sciences Auburn University Auburn AL36849 Alabama USA 4. College of Arts and sciences of Beijing Union university 100083 Beijing China

By using digital satellite remote sensing data acquired in 1987―1989 and 1999―2000 and GIS combined with the natural and socio-economic data, this paper drew an integrated zonation of the cropland change and its driving forces in china. The results indicated that the cropland change in the study period was constrained by geographical factors and driven by cli-mate change as well as socio-economic system. Moreover, the regional differences of the drivers for cropland change were significant. In the midwest of china, natural condition changes and geographical background were the main constraints and drivers, while in Eastern china, social and economic changes and economic policies were the main driving forces. The cropland loss was nationwide. The dominant factors to cause this decrease included buildup of developing area to attract foreign capital and technologies, changes of industry structure due to urban in-fluence, the change of employment notions thanks to living standard improvement, rapid ur-banization due to the expansion of cities and towns, the diminished farming net income partly because of the global warming effects, and the rapid economic growth stimulated by the con-venient transportation system. These factors interact and interdepend with each other to cause the cropland loss in china recently. The reasons for the increase of cropland were primarily the cultivation and deforestation by the farmers who want to increase income. This study on the mechnism of LUCC relied on the cropland change integrated classification considering the natural or human factors both inside and outside the region, which provides a new approach to study the integrated regionalization and LUCC mechanism.

关键词： land use change, driving force, integrated classification, spatial statistics, cropland, china.

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The effects of shock wave and quasi-traveling wave in the mechanical impact test

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Science china(Technological sciences) 2010年第9期53卷 2535-2541页

作者： WU Mei1,5,SUN ZhongFeng2,ZHANG LuMei3,CHEN Yong1 & JI LinHong4.1 Institute of High Energy Physics,Chinese academy of sciences,Beijing 10004.,china 2 School of Mathematical sciences,Peking university,Beijing 100871,china 3 High School of Central university for Nationalities,Beijing 100081,china 4.Institute of Mechanical Design,Department of Precision Instruments and Mechanology,Tsinghua university,Beijing 100084.china 5 academy of Opto-electronics,Chinese academy of sciences,Beijing 100190,china 1. Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China5. Academy of Opto-electronics Chinese Academy of Sciences Beijing 100190 China2. School of Mathematical Sciences Peking University Beijing 100871 China3. High School of Central University for Nationalities Beijing 100081 China4. Institute of Mechanical Design Department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 China

It is well-known that the numerical value is always larger than the measured value,amounting to many times,if we calculate the stress of the specimen in the impulse test using the NASTRAN and ANSYS (N-A) *** believe that the impact induces shock wave or quasi-traveling wave in the specimen,which can qualitatively explain the discrepancy of the two *** order to verify it,the Lax-Friedrichs (L-F) scheme is taken to simulate the transmission of shock wave and quasi-traveling wave in *** results show that the action area of the stress wave is small and the action time is very short,so the resulting stress and actual work are not *** addition,the distribution of the impact values obtained by the numerical simulation is in accordance with the trend of the measured impact values.

关键词： aerospace environment test shock wave quasi-traveling wave

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Identification and removal of block ambiguities in sea surface wind field with scatterometers

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Science china Earth sciences 2009年第2期52卷 242-249页

作者： CHEN KeHai1,2, XIE XueTong3 & FANG Yu4.1 South china Sea Institute of Oceanology, Chinese academy of sciences, Guangzhou 510301, china 2 {4. university of Chinese academy of sciences, Beijing 10004., china 3 School of Electronic Science and Engineering, National university of Defense Technology, Changsha 4.0073, china 4.The Institute of Remote Sensing and GIS, Peking university, Beijing 100871, china 1. South china Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China 2. graduate university of Chinese academy of sciences Beijing 100049 China 3. School of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China 4. The Institute of Remote Sensing and GIS Peking University Beijing 100871 China

The solution of the current wind retrieval algorithm for scatterometers has several wind vector ambi-guities, due to the bi-harmonic relationship between normalized backscattering cross section and the relative wind direction and the existence of the measurement error. In order to remove the ambiguities for a unique wind field, a circular median filter approach (CMF) is usually adopted. But under the con-dition for clustering distribution of the false ambiguities in some local areas, the CMF fails and thus engenders block ambiguities, which degrade the precision of the retrieved wind field. For such a situation, a technique of identification and removal of the block ambiguities is presented to further optimize the retrieved wind field after CMF. It is demonstrated in experiment that this technique can identify and remove most of the block ambiguities.

关键词： scatterometer block ambiguity identification and removal

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Sea-salt aerosol transport patterns over the Northern Hemisphere inferred from two subarctic ice core records

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Science china Earth sciences 2005年第4期48卷 576-584页

作者： YAN Yuping1,2, KANG Shichang2,3,5, SUN Junying4.5, Paul A. Mayewski2 & QIN Dahe5 1. National Climate Center, china Meteorological Administration, Beijing 100081, china 2. Climate Change Institute, university of Maine, Orono, ME 04.69, USA 3. Institute of Tibetan Plateau Research, Chinese academy of {4., Beijing 100085, china 4. Chinese academy of Meteorological {4., Beijing 100081, china 5. Key Laboratory of Ice Core and Cold Regions Environment, Cold and Arid Environmental and Engineering Research Institute, Chinese academy of {4., Lanzhou 730000, china 1. National Climate Center China Meteorological Administration 100081 Beijing China 2. Climate Change Institute University of Maine 04469 Orono ME USA 3. Institute of Tibetan Plateau Research Chinese Academy of Sciences 100085 Beijing China 4. Key Laboratory of Ice Core and Cold Regions Environment Cold and Arid Environmental and Engineering Research Institute Chinese Academy of Sciences 730000 Lanzhou China 5. Chinese academy of Meteorological sciences 100081 Beijing China

Atmospheric circulation reconstruction based on glaciochemical records requires knowledge of chemical concentration controls, such as source, transport pathway and strength. To gain insight into these processes, the relationships between glaciochemical records from two Northern Hemisphere sites (Mt. Logan in Yukon Territory and 20D in southern Greenland) and instrumental sea level pressure (SLP) series are investigated. Calibrations between Mt. Logan sea-salt sodium (ssNa+) concentration and SLP series show that ssNa+ concentrations are closely correlated with the autumntime (SON) Aleutian Low and the summertime (JJA) North Pacific Subtropical High. Both the deepened Aleutian Low and enhanced North Pacific Sub- tropical High strengthen the transport of sea-salt aerosols from the North Pacific to the Mt. Logan region. Calibrations between 20D ssNa+ concentrations and SLP series indicate that ssNa+ concentrations are closely related to the wintertime (Jan.) Icelandic Low. A deepening of the Icelandic Low strengthens winter storms and frequent cyclogenesis over the North Atlantic and pushes more sea-salt laden air masses to the Greenland ice sheet. Therefore, ice core ssNa+ records from the Mt. Logan region can be considered as a proxy for reconstructing the au- tumntime Aleutian Low and summertime North Pacific Subtropical High, and the ssNa+ records from Greenland ice core (20D) may provide a proxy for reconstructing the wintertime Icelandic Low.

关键词： sea-salt aerosol, ice core records, sea level pressure, subarctic regions.

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Rate of strong consistency of quasi maximum likelihood estimate in generalized linear models

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Science china Mathematics 2004年第6期47卷 882-893页

作者： YUE Li & CHEN Xiru School of Mathematics and Statistics, Wuhan university, Wuhan 4.0072, china graduate School, Chinese academy of {4., Beijing 100039, china 1. School of Mathematics and Statistics Wuhan University 430072 Wuhan China 2. graduate School Chinese Academy of Sciences 100039 Beijing China

Under the assumption that in the generalized linear model (GLM) the expectation of the response variable has a correct specification and some other smooth conditions, it is shown that with probability one the quasi-likelihood equation for the GLM has a solution when the sample size n is sufficiently large. The rate of this solution tending to the true value is determined. In an important special case, this rate is the same as specified in the LIL for iid partial sums and thus cannot be improved anymore.

关键词： quasi-likelihood function generalized linear models strong consistency

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