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A comparative study of long-time series of global-scale albedo products

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International Journal of Digital Earth 2023年第1期16卷 308-322页

作者： Li Mengyao Liu Qiang Qu Ying College of Global Change and Earth System Science State Key Laboratory of Remote Sensing ScienceBeijing Normal UniversityBeijingPeople’s Republic of China Pengcheng Laboratory ShenzhenPeople’s Republic of China School of Geographical Sciences Northeast Normal UniversityChangchunPeople’s Republic of China

albedo is a key variable in the study of global or regional earth system ***-quality albedo products are helpful for the accurate analysis and prediction of the Earth’s environment and *** paper analyzes the similarities and differences in several global-scale albedo *** conclusions are as follows:(1)Ignoring the downward radiation weight leads to a maximum deviation of±0.2 in the mean albedo in space and time;(2)Most of the products have good consistency at the global scale,especially after 2000,the consistency in the middle latitudes is better than that in the low latitudes and high latitudes;(3)Although there are obvious inter-annual variations and zonal differences in global mean albedo data from 2000 to 2020,the overall trend is not *** complex spatio-temporal variation of albedo requires high-quality remote sensing products to characterize its ***,existing datasets do not show good agreement in these details,and more efforts are needed in this area.

关键词： albedo remote sensing assessment spatio-temporal variation

Changes in albedo and its radiative forcing of grasslands in East Asia drylands

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Ecological Processes 2024年第1期13卷 237-251页

作者： Qingsong Zhu Jiquan Chen Liangxu Wu Yuting Huang Changliang Shao Gang Dong Zhe Xu Xianglan Li State Key Laboratory of Remote Sensing Science College of Global Change and Earth System Science Faculty of Geographical ScienceBeijing Normal University Department of Geography Environment and Spatial Sciences Michigan State University State Key Laboratory of Efficient Utilization of Arid and Semi-Arid Arable Land in Northern China National Hulunber Grassland Ecosystem Observation and Research Station Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences School of Life Science Shanxi University

Background Grasslands in drylands are increasingly influenced by human activities and climate change, leading to alterations in albedo and radiative energy balance among others. Surface biophysical properties and their interactions change greatly following disturbances. However, our understanding of these processes and their climatic impacts remains limited. In this study, we used multi-year observations from satellites and eddy-covariance towers to investigate the response of albedo to variables closely associated with human disturbances, including vegetation greenness（EVI） and surface soil volumetric water content（VWC）, as well as snow cover and clearness index（Ta） for their potential *** EVI and VWC during the growing season were the primary factors influencing albedo. EVI and VWC were negatively correlated with albedo, with VWC's total direct and indirect impacts being slightly smaller than those of EVI. During the non-growing season, snow cover was the most influential factor on albedo. VWC and Ta negatively affected albedo throughout the year. We estimated the impact of variations in EVI and VWC on climate to be in the range of 0.004 to 0.113 kg CO2m-2yr-1in *** This study indicates the significant impacts of climate change and human disturbances on vulnerable grassland ecosystems from the perspective of altered albedo. Changes in vegetation greenness and soil properties induced by climate change and human activities may have a substantial impact on albedo, which in turn feedback on climate change, indicating that future climate policies should take this factor into consideration.

关键词： albedo Global warming potential Grassland Disturbance

Impact of surface albedo on Martian photochemistry

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Earth and Planetary Physics 2020年第3期4卷 206-211页

作者： Deepak Singh Physical Research Laboratory AhmedabadIndia

Solar energy is the primary driving force behind a planet’s climate system,and surface albedo plays a key role in determining the energy budget of the *** the Snow,Ice,and Aerosol Radiation(SNICAR)with the Laboratoire de Météorologie Dynamique(LMD)Mars General Circulation Model(MGCM)to create a new coupled model leads to an approximately 4%drop in the net CO2 ice deposition on *** simulated surface albedo affects the concentration of gaseous species in the Martian atmosphere(condensation-sublimation cycle).The new set-up also impacts the solar energy available in the *** two effects together lead to subsequent and significant changes in other chemical species in the Martian *** with results of the MGCM model alone,in the new coupled model CO2(gas)and O3 show a drop of about 1.17%and 8.59%in their respective concentrations,while H2O(vapor)and CO show an increase of about 13.63%and 0.56%in their respective *** trace species,OH shows a maximum increase of about 29.44%,while the maximum drop of 11.5%is observed in the O *** neutral species such as Ar and N2 remain unaffected by the albedo changes.

关键词： Mars albedo snow photochemistry climate modelling

Calculation of Solar albedo and Radiation Equilibrium over the Qinghai-Xizang Plateau and Analysisof Their Climatic Features

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Advances in Atmospheric Sciences 2000年第1期17卷 140-156页

作者：赵平陈隆勋 Chinese Academy of Meteorological Sciences Beijing

Using radiation data from the Automatic Weather Stations (AWSs) for thermal balance obser-vations, which were set up at Lhasa, Nagqu, Xigaze and Nyingchi by the Sino-Japanese Asian Monsoon Mechanism Co-operative Project in 1993–1996, and 1985–1989 Earth Radiation Balance Experiment (ERBE) measurements of Langley Research Center/NASA of US, and 1961–1996 monthly mean data from 148 surface stations over the Qinghai-Xizang Plateau (QXP) and its neighborhood, study is performed on empirical calculation methods of surface albedo, surface total radiation, planetary albedo and outgoing longwave radiation with the climatic features of radiation balance at the surface and the atmospheric top examined. Evidences suggest that the empirical formulae for surface albedo, planetary albedo, surface to-tal radiation and outgoing longwave radiation from the atmospheric top are capable of describing their seasonal and interannual variations over the QXP. The surface albedo is marked by noticeable seasonal variation and yearly mean of 0.22 with the maximum of 0.29 in January and minimum of 0.17 in July and August; in winter the albedo has great horizontal difference, bigger in the moun-tains than in the river valleys, and small in summer. The planetary albedo shows a smaller range of its annual variation with the yearly mean of 0.37, the maximum (minimum) occurring in February and March (autumn). In winter its high-value regions are mainly at Gar (Shiquanhe) in the western QXP and from the southwestern Qinghai to the northeastern Tibet and the low-value area at the northern slope of the central Himalayas; in summer, however, the albedo distribution displays clear-ly a progressive decrease from southeast to northwest. As for the surface total radiation, its values and annual varying range are smaller in the east than in the southwest. Its high-value center is at the southern slope of the Himalayas in winter and makes a conspicuous westward migration in spr-ing, remaining there for a lon

关键词： The Qinghai-Xizang Plateau albedo Radiation balance Climatic feature

Comprehensive Study on the Influence of Evapotranspiration and albedo on Surface Temperature Related to Changes in the Leaf Area Index

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Advances in Atmospheric Sciences 2015年第7期32卷 935-942页

作者： ZHU Jiawen ZENG Xiaodong International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology

Many studies have investigated the influence of evapotranspiration and albedo and emphasize their separate effects but ignore their interactive influences by changing vegetation status in large amplitudes. This paper focuses on the comprehensive influence of evapotranspiration and albedo on surface temperature by changing the leaf area index （LAD between 30^-90~N. Two LAI datasets with seasonally different amplitudes of vegetation change between 30^-90~N were used in the simulations. Seasonal differences between the results of the simulations are compared, and the major findings are as follows. （1） The interactive effects of evapotranspiration and albedo on surface temperature were different over different regions during three seasons [March-April-May （MAM）, June-July-August （JJA）, and September-October-November （SON）], i.e., they were always the same over the southeastern United States during these three seasons but were opposite over most regions between 30°-90°N during JJA. （2） Either evapotranspiration or albedo tended to be dominant over different areas and during different seasons. For example, evapotranspiration dominated almost all regions between 30^-90~N during JJA, whereas albedo played a dominant role over northwestern Eurasia during MAM and over central Eurasia during SON. （3） The response of evapotranspiration and albedo to an increase in LAI with different ranges showed different paces and signals. With relatively small amplitudes of increased LAI, the rate of the relative increase in evapotranspiration was quick, and positive changes happened in albedo. But both relative changes in evapotranspiration and albedo tended to be gentle, and the ratio of negative changes of albedo increased with relatively large increased amplitudes of LAI.

关键词： surface temperature evapotranspiration albedo leaf area index comprehensive influence

Forward a spatio-temporal trend surface for long-term groundmeasured albedo upscaling over heterogeneous land surface

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International Journal of Digital Earth 2018年第5期11卷 470-484页

作者： Xiaodan Wu Jianguang Wen Qing Xiao Dongqin You Qiang Liu Xingwen Lin State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingPeople’s Republic of China College of Resources and Environment University of Chinese Academy of SciencesBeijingPeople’s Republic of China Joint Center for Global Change Studies BeijingPeople’s Republic of China College of Global Change and Earth System Science Beijing Normal UniversityBeijingPeople’s Republic of China

Upscaling ground albedo is challenged by the serious discrepancy between the heterogeneity of land surfaces and the small number of ground-based *** ground-based measurements cannot provide sufficient information on the characteristics of surface albedo at the scale of coarse pixels over heterogeneous land *** method of overcoming this problem is to introduce high-resolution albedo imagery as ancillary information for ***,due to the low frequency of updating of high-resolution albedo maps,upscaling time series of ground-based albedo measurements is *** paper proposes a method that is based on the idea of conceptual universal scaling methodology for establishing a spatiotemporal trend surface using very few high-resolution images and time series of ground-based measurements for spatial-temporal upscaling of *** construction of the spatiotemporal trend surface incorporates the spatial information provided by auxiliary remote sensing images and the temporal information provided by long time series of ground *** approach was illustrated by upscaling ground-based fine-scale albedo measurements to a coarse scale over the core study area in *** results indicate that this method can characterize the spatiotemporal variations in surface albedo well,and the overall correlation coefficient was 0.702 during the study period.

关键词： Trend surface upscaling spatiotemporal heterogeneous albedo

A web-based land surface remote sensing products validation system (LAPVAS): application to albedo product

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International Journal of Digital Earth 2018年第3期11卷 308-328页

作者： Xingwen Lin Jianguang Wen Yong Tang Mingguo Ma Dongqin You Baocheng Dou Xiaodan Wu Xiaobo Zhu Qing Xiao Qinghuo Liu State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingPeople’s Republic of China University of Chinese Academy of Sciences BeijingPeople’s Republic of China Joint Center for Global Change Studies BeijingPeople’s Republic of China School of Geographical Sciences Southwest UniversityChongqingPeople’s Republic of China College of Global Change and Earth System Science Beijing Normal UniversityBeijingPeople’s Republic of China

Quantitative remote sensing product(QRSP)validation is a complex process to assess the accuracy and uncertainty independently using reference data with multiple land cover types and long-time series.A web-based system named as LAnd surface remote sensing Product VAlidation system(LAPVAS)is described in this paper,which is used to implement the QRSPs validation process *** LAPAVS has two subsystems,the Validation Databases Subsystem and the Accuracy Evaluation *** functions have been implemented by the two subsystems for a comprehensive QRSP validation:(1)a standardized processing of reference data and storage of these data in validation databases;(2)a consistent and comprehensive validation procedure to assess the QRSPs’accuracy and uncertainty;and(3)a visual process customization tool with which the users can register new validation data,host new reference data,and readjust the validation workflows for the QRSP accuracy *** LAPVAS,more than 100 GB of reference data warehoused in validation databases for 13 types of QRSPs’*** of the key QRSPs,land surface albedo,is selected as an example to illustrate the application of *** is demonstrated that the LAPVAS has a good performance in the land surface remote sensing product validation.

关键词： Remote sensing validation system LAPVAS uncertainty information albedo

Upscaling in situ albedo for validation of coarse scale albedo product over heterogeneous surfaces

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International Journal of Digital Earth 2017年第6期10卷 604-622页

作者： Xiaodan Wu Qing Xiao Jianguang Wen Qiang Liu Dongqin You Baocheng Dou Yong Tang State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingPeople’s Republicof China College of Resourcesand Environment University of Chinese Academy of SciencesBeijingPeople’s Republic of China Joint Center for Global Change Studies BeijingPeople’s Republic of China College of Global Change and Earth System Science Beijing Normal UniversityBeijingPeople’s Republic of China

One of the essential steps for satellite albedo validation is upscaling in situ measurements to corresponding pixel scale over relatively heterogeneous land *** the multi-scale validation strategy is applicable for heterogeneous surfaces,the calibration of the high-resolution imagery during upscaling process is never perfect,and thus the upscaling results suffer from *** regression-kriging(RK)technique can compensate the calibration part by applying kriging to upscale residuals and produce more accurate upscaling *** this paper,in situ measurements and high spatial resolution albedo imagery combined with RK technique was *** method is illustrated by upscaling surface albedo from in situ measurements scale to the coarse pixel scale in the core experimental area of HiWATER,where 17 WSN nodes were deployed at heterogeneous *** upscaling results of this method were compared with the upscaling results from multi-scale *** results show that the upscaling method based on in situ measurements and high-resolution imagery combined with RK technique can capture the spatial characteristics of surface albedo ***,an attempt was made to expand this method in time ***,a preliminary validation of the Moderate Resolution Imaging Spectroradiometer albedo product was performed as the tentative application.

关键词： Upscaling albedo heterogeneous validation in situ multi-scale

Calculation of thermal neutron albedo for mono-material and bi-material reflectors

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Nuclear Science and Techniques 2018年第9期29卷 185-191页

作者： Sara Azimkhani Farhad Zolfagharpour Farhood Ziaie Department of Physics University of Mohaghegh Ardabili Radiation Application Research School Nuclear Science & Technology Research Institute

Thermal neutron albedo has been investigated for different thicknesses of mono-material and bi-material reflectors. An equation has been obtained for a bi-material reflector by considering the neutron diffusion equation. The bi-material reflector consists of binary combinations of water, graphite, lead, and polyethylene. An experimental measurement of thermal neutron albedo has also been conducted for mono-material and bi-material reflectors by using a^(241) Am–Be(5.2 Ci) neutron source and a BF3 detector. The maximum value of thermal neutron albedo was obtained for a polyethylene–water combination(0.95 ± 0.02).

关键词： Neutron current Bi-material reflector Thermal neutron albedo BF3 detector Reflection Diffusion equation