黑碳(BC)作为可吸入颗粒物PM_(2.5)的重要组成部分,由于其特殊的理化性质,对大气环境和人类健康构成严重威胁。目前,我国尚未建立完善的大气黑碳浓度地面观测网络和数据共享体系,区域尺度黑碳浓度产品的精度验证和适用性评价比较有限。...黑碳(BC)作为可吸入颗粒物PM_(2.5)的重要组成部分,由于其特殊的理化性质,对大气环境和人类健康构成严重威胁。目前,我国尚未建立完善的大气黑碳浓度地面观测网络和数据共享体系,区域尺度黑碳浓度产品的精度验证和适用性评价比较有限。本文从已发表文献中提取我国126个站点的1616个BC月监测数据,时间跨度为2000−2020年,对MERRA-2(Modern-Era Retrospective Analysis for Research and Applications,Version 2)和TAP(Tracking Air Pollution in China)的BC数据进行全面的精度验证和适用性评价。结果表明:①MERRA-2与TAP均低估了我国大气BC浓度,其中MERRA-2低估程度为8.13%,TAP低估程度为19.51%。TAP的大气BC浓度与地面站点监测数据的相关性〔R=0.62,模拟实测两倍因子(FAC2)=0.69〕高于MERRA-2(R=0.46,FAC2=0.58),MERRA-2的20年平均大气BC浓度(3.61μg/m^(3))更接近地面站点平均大气BC浓度(3.97μg/m^(3))。②MERRA-2和TAP的大气BC浓度在我国不同地区的精度存在较大差别,MERRA-2在我国华北和西南地区的精度优于TAP。两个数据集在西南地区都有较高的精度(R为0.68~0.84,FAC2为0.71~0.79),在华北地区精度均较低(R为0.41~0.48,FAC2为0.64~0.77)。③MERRA-2与TAP大气BC浓度在全国大部分地区呈显著正相关,其中,二者在四川省大气BC浓度差异(0.0045μg/m^(3))最小,在北京市差异(2.11μg/m^(3))最大。研究显示,MERRA-2有更长的时间跨度,而TAP更能准确表现大气BC浓度的空间分布,且二者在不同地区表现出较大差异。展开更多
This paper evaluates a representation of winter stratospheric circulation in the Antarctic that is based on CRA-40, a 40-year global reanalysis dataset released by the China Meteorological Administration, and compares...This paper evaluates a representation of winter stratospheric circulation in the Antarctic that is based on CRA-40, a 40-year global reanalysis dataset released by the China Meteorological Administration, and compares it with representations based on two other state-of-the-art reanalysis datasets: the fifth-generation atmospheric reanalysis provided by the European Centre for Medium-Range Weather Forecasts(ERA-5) and the Modern-Era Retrospective analysis for Research and Applications, version 2(MERRA-2). In terms of climatology, we find that CRA-40 portrays a stronger and colder polar vortex in the middle and lower stratosphere than ERA-5, but a weaker and warmer one than MERRA-2. However, disagreement among the three reanalyses is confined mainly to the period before1999, and is largely reduced after that time. On the interannual timescale, portrayals of the intensity and area of the 10-hPa polar vortex are quite consistent among the three reanalyses, with correlation coefficients greater than 0.9 between each pair of reanalyses. In addition, the central dates of most sudden stratospheric deceleration(SSD) events at 10 hPa in the three reanalyses differ by less than one day, indicating that CRA-40 is also highly consistent with the other two reanalysis datasets regarding daily evolution. Our analyses suggest that CRA-40 performs comparably to ERA-5 and MERRA-2 in characterizing winter circulation in the Antarctic middle and lower stratosphere.展开更多
Temperature and pressure play key roles in Global Navigation Satellite System(GNSS)precipitable water vapor(PWV)retrieval.The National Aeronautics and Space Administration(NASA)and European Center for Medium-Range Wea...Temperature and pressure play key roles in Global Navigation Satellite System(GNSS)precipitable water vapor(PWV)retrieval.The National Aeronautics and Space Administration(NASA)and European Center for Medium-Range Weather Forecasts(ECMWF)have released their latest reanalysis product:the modern-era retrospective analysis for research and applications,version 2(MERRA-2)and the fifthgeneration ECMWF reanalysis(ERA5),respectively.Based on the reanalysis data,we evaluate and analyze the accuracy of the surface temperature and pressure products in China using the the measured temperature and pressure data from 609 ground meteorological stations in 2017 as reference values.Then the accuracy of the two datasets and their performances in estimating GNSS PWV are analyzed.The PWV derived from the pressure and temperature products of ERA5 and MERRA-2 has high accuracy.The annual average biases of pressure and temperature for ERA5 are-0.07 hPa and 0.45 K,with the root mean square error(RMSE)of 0.95 hPa and 2.04 K,respectively.The annual average biases of pressure and temperature for MERRA-2 are-0.01 hPa and 0.38 K,with the RMSE of 1.08 h Pa and 2.66 K,respectively.The accuracy of ERA5 is slightly higher than that of MERRA-2.The two reanalysis data show negative biases in most regions of China,with the highest to lowest accuracy in the following order:the south,north,northwest,and Tibet Plateau.Comparing the GNSS PWV calculated using MERRA-2(GNSS MERRA-2 PWV)and ERA5(GNSS ERA5 PWV)with the radiosonde-derived PWV from 48 co-located GNSS stations and the measured PWV of the co-location radiosonde stations,it is found that the accuracy of GNSS ERA5 PWV is better than that of GNSS MERRA-2 PWV.These results show the different applicability of surface temperature and pressure products from MERRA-2 and ERA5 data,indicating that both have important applications in meteorological research and GNSS water vapor monitoring in China.展开更多
Rapid industrialization and urbanization along with a growing population are contributing significantly to air pollution in China.Evaluation of long-term aerosol optical depth(AOD)data from models and reanalysis,can g...Rapid industrialization and urbanization along with a growing population are contributing significantly to air pollution in China.Evaluation of long-term aerosol optical depth(AOD)data from models and reanalysis,can greatly promote understanding of spatiotemporal variations in air pollution in China.To do this,AOD(550 nm)values from 2000 to 2014 were obtained from the Coupled Model Intercomparison Project(CIMP6),the second version of Modern-Era Retrospective analysis for Research,and Applications(MERRA-2),and the Moderate Resolution Imaging Spectroradiometer(MODIS;flying on the Terra satellite)combined Dark Target and Deep Blue(DTB)aerosol product.We used the TerraMODIS DTB AOD(hereafter MODIS DTB AOD)as a standard to evaluate CMIP6 Ensemble AOD(hereafter CMIP6 AOD)and MERRA-2 reanalysis AOD(hereafter MERRA-2 AOD).Results show better correlations and smaller errors between MERRA-2 and MODIS DTB AOD,than between CMIP6 and MODIS DTB AOD,in most regions of China,at both annual and seasonal scales.However,significant under-and over-estimations in the MERRA-2 and CMIP6 AOD were also observed relative to MODIS DTB AOD.The long-term(2000-2014)MODIS DTB AOD distributions show the highest AOD over the North China Plain(0.71)followed by Central China(0.69),Yangtse River Delta(0.67),Sichuan Basin(0.64),and Pearl River Delta(0.54)regions.The lowest AOD values were recorded over the Tibetan Plateau(0.13±0.01)followed by Qinghai(0.19±0.03)and the Gobi Desert(0.21±0.03).Large amounts of sand and dust particles emitted from natural sources(the Taklamakan and Gobi Deserts)may result in higher AOD in spring compared to summer,autumn,and winter.Trends were also calculated for 2000-2005,for2006-2010(when China introduced strict air pollution control policies during the 11 th Five Year Plan or FYP),and for 2011-2014(during the 12 th FYP).An increasing trend in MODIS DTB AOD was observed throughout the country during 2000-2014.The uncontrolled industrialization,urbanization,and rapid economic development that mostly occurred from 2000 to 2005 probably contributed to the overall increase in AOD.Finally,China’s air pollution control policies helped to reduce AOD in most regions of the country;this was more evident during the 12 th FYP period(2011-2014)than during the 11 th FYP period(2006-2010).Therefore this study strongly advises the authority to retain or extend these policies in the future for improving air quality.展开更多
The sulfur pollutants are the source of a sizeable portion of the air pollution. In this work, the recent spatiotemporal distribution and trend of the mass concentration of two of the critical sulfur pollutants, SO2 a...The sulfur pollutants are the source of a sizeable portion of the air pollution. In this work, the recent spatiotemporal distribution and trend of the mass concentration of two of the critical sulfur pollutants, SO2 and SO4, in addition to the aerosol optical properties (AOD) were analyzed over the region of the Middle East and North Africa (MENA) from satellite and Modern Era-Retrospective Analysis for Research and Applications version 2 (MERRA-2) reanalysis data. The SO2 and SO4 data used in these analyses are obtained from (MERRA-2) with a resolution of 0.5° × 0.625° throughout a period of 10 years (2005-2015). On the other hand, the temporal trend and spatial distribution of AOD were identified from four different satellite data. 1) moderate-resolution imaging spectroradiometer (MODIS) Level 3 AOD data at 550 nm wavelengths from Collection 6 algorithm (combined dark target and deep blue algorithms) are used for 10 years temporal analysis (2006-2015). 2) Multi-angle imaging spectroradiometer (MISR) with 0.5 deg spatial resolution for the same 10 years (2006-2015). 3) Sea-Viewing Wide Field-of-View Sensor (SeaWIFS) with 0.5 deg for the period (2005-2010). 4) Ozone Monitoring Instrument (OMI) AOD at 500 nm wavelength with resolution 1 degree. This study presents more resent 10 years of Spatiotemporal of SO2, SO4 and AOD over MENA domain.展开更多
Black carbon(BC),which is one of the short-lived climate forcers,largely influencesthe local modulation of the climate,particularly in regions that aresensitive such as East Africa.However,the long-term trends and met...Black carbon(BC),which is one of the short-lived climate forcers,largely influencesthe local modulation of the climate,particularly in regions that aresensitive such as East Africa.However,the long-term trends and meteorologicalimpacts of BC in this region remain not very well investigated,especiallyconsidering the context of altered anthropogenic and natural emissionsources.This study bridges this gap through a comprehensive spatio-temporalexamination of BC surface mass concentration for East Africa from 1980 to2023 using data from the Modern-Era Retrospective Analysis for Research andApplications,Version 2(MERRA-2).It has also established statistical correlationbetween BC concentrations and the selected meteorological parameters,i.e.,surface air temperature,specific humidity,surface wind speed,and totalsurface precipitation.Time-series analysis,spatial visualization,and Pearsoncorrelation were applied to analyze the MERRA-2 datasets.Results showedpronounced intra-and inter-annual variability in BC distribution with highconcentrations(>8×10^(-12)kg/m^(3))mostly over western Uganda and northwesternKenya and Tanzania during boreal winter.Such space hotspots werelinked to both local sources(biomass burning,automobile pollution)andlong-range atmospheric transport from Asian and Middle Eastern industrialregions.The effect of natural sources such as West African bushfires and Saharandust storms,was also reflected by transboundary dispersion patternsdue to wind systems in operation.Correlation analysis found that surface windspeed showed a statistically significant negative correlation with BC concentrationsduring all seasons,particularly March-May(r=-0.57,R^(2)=0.31)andJune-August(r=-0.51,R^(2)=0.24),indicating high winds favour BC dispersion.Specific humidity in addition to precipitation was moderately positivelycorrelated with BC,particularly during the September-November season(r=0.47,R^(2)=0.20),showing complex interactions between atmospheric moistureand aerosol lifecycles.Surface air temperature was most strongly seasonallycorrelated with BC during the short rains(r=0.55,R^(2)=0.29),showing thetwo-way effect of BC on atmospheric warming and radiative forcing.In short,the investigation indicates that BC concentrations over East Africa exhibit distinctspatial and temporal patterns driven by both human and natural processes.The statistically significant correlations with meteorological parametersprove the modulating role of BC in regional climate processes.Policymakersmust prioritize emission control actions targeted at biomass burning andurban pollution,and scientists must keep investigating high-resolution BCclimateinteractions using integrated ground and satellite observations to advanceclimate impact assessment in East Africa.展开更多
遥感反演土壤水分(SM)产品越来越多地应用于农业、气象、水文等研究,而微波土壤水分数据产品的区域适用性分析是其合理使用的必要前提。使用MERRA-2(Modern Era Retrospective-analysis for Research and Applications,Version 2)模拟...遥感反演土壤水分(SM)产品越来越多地应用于农业、气象、水文等研究,而微波土壤水分数据产品的区域适用性分析是其合理使用的必要前提。使用MERRA-2(Modern Era Retrospective-analysis for Research and Applications,Version 2)模拟土壤水分为参考数据,运用传统统计方法(原始数据相关性、距平相关性、偏差以及无偏均方根差)和TC(Triple-Collocation)不确定性误差模型分析的方法,对亚洲区域2012年7月～2016年7月两种被动微波土壤水分SMOS-L3-SM(Soil Moisture and Ocean Salinity,L3)和AMSR2-LPRM-SM(The Advanced Microwave Scanning Radiometer 2,Land Parameter Retrieval Model Product)进行对比评估。结果表明:①空间上SMOS-L3较AMSR2-LPRM数据与参考数据MERRA-2土壤水分的相关性较好,表现为SMOS-L3-SM具有较好的空间连续性,且在亚洲大多数地区有较小的无偏均方根差;②湿季条件下遥感土壤水分与参考值的相关性比干季条件下的相关性更好,且干季出现高纬地区(约>55°)缺失值较多的情况;③两遥感土壤水分的TC误差呈现相似的分布,区域TC平均误差两者均为0.076 m^3/m^3。总之,SMOS-L3-SM和AMSR2-LPRM-SM在空间相关性及TC误差评价方面都具有合理性,为遥感土壤水分在农业、气象、水文等方面的应用提供参考。展开更多
文摘黑碳(BC)作为可吸入颗粒物PM_(2.5)的重要组成部分,由于其特殊的理化性质,对大气环境和人类健康构成严重威胁。目前,我国尚未建立完善的大气黑碳浓度地面观测网络和数据共享体系,区域尺度黑碳浓度产品的精度验证和适用性评价比较有限。本文从已发表文献中提取我国126个站点的1616个BC月监测数据,时间跨度为2000−2020年,对MERRA-2(Modern-Era Retrospective Analysis for Research and Applications,Version 2)和TAP(Tracking Air Pollution in China)的BC数据进行全面的精度验证和适用性评价。结果表明:①MERRA-2与TAP均低估了我国大气BC浓度,其中MERRA-2低估程度为8.13%,TAP低估程度为19.51%。TAP的大气BC浓度与地面站点监测数据的相关性〔R=0.62,模拟实测两倍因子(FAC2)=0.69〕高于MERRA-2(R=0.46,FAC2=0.58),MERRA-2的20年平均大气BC浓度(3.61μg/m^(3))更接近地面站点平均大气BC浓度(3.97μg/m^(3))。②MERRA-2和TAP的大气BC浓度在我国不同地区的精度存在较大差别,MERRA-2在我国华北和西南地区的精度优于TAP。两个数据集在西南地区都有较高的精度(R为0.68~0.84,FAC2为0.71~0.79),在华北地区精度均较低(R为0.41~0.48,FAC2为0.64~0.77)。③MERRA-2与TAP大气BC浓度在全国大部分地区呈显著正相关,其中,二者在四川省大气BC浓度差异(0.0045μg/m^(3))最小,在北京市差异(2.11μg/m^(3))最大。研究显示,MERRA-2有更长的时间跨度,而TAP更能准确表现大气BC浓度的空间分布,且二者在不同地区表现出较大差异。
基金jointly supported by the NSFC project (42088101, 41975048, 42361144843, 42175069)。
文摘This paper evaluates a representation of winter stratospheric circulation in the Antarctic that is based on CRA-40, a 40-year global reanalysis dataset released by the China Meteorological Administration, and compares it with representations based on two other state-of-the-art reanalysis datasets: the fifth-generation atmospheric reanalysis provided by the European Centre for Medium-Range Weather Forecasts(ERA-5) and the Modern-Era Retrospective analysis for Research and Applications, version 2(MERRA-2). In terms of climatology, we find that CRA-40 portrays a stronger and colder polar vortex in the middle and lower stratosphere than ERA-5, but a weaker and warmer one than MERRA-2. However, disagreement among the three reanalyses is confined mainly to the period before1999, and is largely reduced after that time. On the interannual timescale, portrayals of the intensity and area of the 10-hPa polar vortex are quite consistent among the three reanalyses, with correlation coefficients greater than 0.9 between each pair of reanalyses. In addition, the central dates of most sudden stratospheric deceleration(SSD) events at 10 hPa in the three reanalyses differ by less than one day, indicating that CRA-40 is also highly consistent with the other two reanalysis datasets regarding daily evolution. Our analyses suggest that CRA-40 performs comparably to ERA-5 and MERRA-2 in characterizing winter circulation in the Antarctic middle and lower stratosphere.
基金the National Natural Science Foundation of China(Grant No.42204006)the Guangxi Natural Science Foundation of China(2020GXNSFBA297145)+1 种基金the“Ba Gui Scholars”program of the provincial government of Guangxi,and Innovation Project of GuangXi Graduate Education(Grant No.YCSW2022322)Open Research Fund Program of the Key Laboratory of Geospace Environment and Geodesy,Ministry of Education,China(GrantNo.20-01-03,21-01-04)
文摘Temperature and pressure play key roles in Global Navigation Satellite System(GNSS)precipitable water vapor(PWV)retrieval.The National Aeronautics and Space Administration(NASA)and European Center for Medium-Range Weather Forecasts(ECMWF)have released their latest reanalysis product:the modern-era retrospective analysis for research and applications,version 2(MERRA-2)and the fifthgeneration ECMWF reanalysis(ERA5),respectively.Based on the reanalysis data,we evaluate and analyze the accuracy of the surface temperature and pressure products in China using the the measured temperature and pressure data from 609 ground meteorological stations in 2017 as reference values.Then the accuracy of the two datasets and their performances in estimating GNSS PWV are analyzed.The PWV derived from the pressure and temperature products of ERA5 and MERRA-2 has high accuracy.The annual average biases of pressure and temperature for ERA5 are-0.07 hPa and 0.45 K,with the root mean square error(RMSE)of 0.95 hPa and 2.04 K,respectively.The annual average biases of pressure and temperature for MERRA-2 are-0.01 hPa and 0.38 K,with the RMSE of 1.08 h Pa and 2.66 K,respectively.The accuracy of ERA5 is slightly higher than that of MERRA-2.The two reanalysis data show negative biases in most regions of China,with the highest to lowest accuracy in the following order:the south,north,northwest,and Tibet Plateau.Comparing the GNSS PWV calculated using MERRA-2(GNSS MERRA-2 PWV)and ERA5(GNSS ERA5 PWV)with the radiosonde-derived PWV from 48 co-located GNSS stations and the measured PWV of the co-location radiosonde stations,it is found that the accuracy of GNSS ERA5 PWV is better than that of GNSS MERRA-2 PWV.These results show the different applicability of surface temperature and pressure products from MERRA-2 and ERA5 data,indicating that both have important applications in meteorological research and GNSS water vapor monitoring in China.
基金The National Key Research and Development Program of China(2016YFC1400901)Jiangsu Technology Project of Nature Resources(KJXM2019042)+2 种基金the Jiangsu Provincial Department of Education for the Special Project of Jiangsu Distinguished Professor(R2018T22)the National Natural Science Foundation of China(Grant No.41976165)the Startup Foundation for Introduction Talent of NUIST(2017r107)。
文摘Rapid industrialization and urbanization along with a growing population are contributing significantly to air pollution in China.Evaluation of long-term aerosol optical depth(AOD)data from models and reanalysis,can greatly promote understanding of spatiotemporal variations in air pollution in China.To do this,AOD(550 nm)values from 2000 to 2014 were obtained from the Coupled Model Intercomparison Project(CIMP6),the second version of Modern-Era Retrospective analysis for Research,and Applications(MERRA-2),and the Moderate Resolution Imaging Spectroradiometer(MODIS;flying on the Terra satellite)combined Dark Target and Deep Blue(DTB)aerosol product.We used the TerraMODIS DTB AOD(hereafter MODIS DTB AOD)as a standard to evaluate CMIP6 Ensemble AOD(hereafter CMIP6 AOD)and MERRA-2 reanalysis AOD(hereafter MERRA-2 AOD).Results show better correlations and smaller errors between MERRA-2 and MODIS DTB AOD,than between CMIP6 and MODIS DTB AOD,in most regions of China,at both annual and seasonal scales.However,significant under-and over-estimations in the MERRA-2 and CMIP6 AOD were also observed relative to MODIS DTB AOD.The long-term(2000-2014)MODIS DTB AOD distributions show the highest AOD over the North China Plain(0.71)followed by Central China(0.69),Yangtse River Delta(0.67),Sichuan Basin(0.64),and Pearl River Delta(0.54)regions.The lowest AOD values were recorded over the Tibetan Plateau(0.13±0.01)followed by Qinghai(0.19±0.03)and the Gobi Desert(0.21±0.03).Large amounts of sand and dust particles emitted from natural sources(the Taklamakan and Gobi Deserts)may result in higher AOD in spring compared to summer,autumn,and winter.Trends were also calculated for 2000-2005,for2006-2010(when China introduced strict air pollution control policies during the 11 th Five Year Plan or FYP),and for 2011-2014(during the 12 th FYP).An increasing trend in MODIS DTB AOD was observed throughout the country during 2000-2014.The uncontrolled industrialization,urbanization,and rapid economic development that mostly occurred from 2000 to 2005 probably contributed to the overall increase in AOD.Finally,China’s air pollution control policies helped to reduce AOD in most regions of the country;this was more evident during the 12 th FYP period(2011-2014)than during the 11 th FYP period(2006-2010).Therefore this study strongly advises the authority to retain or extend these policies in the future for improving air quality.
文摘The sulfur pollutants are the source of a sizeable portion of the air pollution. In this work, the recent spatiotemporal distribution and trend of the mass concentration of two of the critical sulfur pollutants, SO2 and SO4, in addition to the aerosol optical properties (AOD) were analyzed over the region of the Middle East and North Africa (MENA) from satellite and Modern Era-Retrospective Analysis for Research and Applications version 2 (MERRA-2) reanalysis data. The SO2 and SO4 data used in these analyses are obtained from (MERRA-2) with a resolution of 0.5° × 0.625° throughout a period of 10 years (2005-2015). On the other hand, the temporal trend and spatial distribution of AOD were identified from four different satellite data. 1) moderate-resolution imaging spectroradiometer (MODIS) Level 3 AOD data at 550 nm wavelengths from Collection 6 algorithm (combined dark target and deep blue algorithms) are used for 10 years temporal analysis (2006-2015). 2) Multi-angle imaging spectroradiometer (MISR) with 0.5 deg spatial resolution for the same 10 years (2006-2015). 3) Sea-Viewing Wide Field-of-View Sensor (SeaWIFS) with 0.5 deg for the period (2005-2010). 4) Ozone Monitoring Instrument (OMI) AOD at 500 nm wavelength with resolution 1 degree. This study presents more resent 10 years of Spatiotemporal of SO2, SO4 and AOD over MENA domain.
文摘Black carbon(BC),which is one of the short-lived climate forcers,largely influencesthe local modulation of the climate,particularly in regions that aresensitive such as East Africa.However,the long-term trends and meteorologicalimpacts of BC in this region remain not very well investigated,especiallyconsidering the context of altered anthropogenic and natural emissionsources.This study bridges this gap through a comprehensive spatio-temporalexamination of BC surface mass concentration for East Africa from 1980 to2023 using data from the Modern-Era Retrospective Analysis for Research andApplications,Version 2(MERRA-2).It has also established statistical correlationbetween BC concentrations and the selected meteorological parameters,i.e.,surface air temperature,specific humidity,surface wind speed,and totalsurface precipitation.Time-series analysis,spatial visualization,and Pearsoncorrelation were applied to analyze the MERRA-2 datasets.Results showedpronounced intra-and inter-annual variability in BC distribution with highconcentrations(>8×10^(-12)kg/m^(3))mostly over western Uganda and northwesternKenya and Tanzania during boreal winter.Such space hotspots werelinked to both local sources(biomass burning,automobile pollution)andlong-range atmospheric transport from Asian and Middle Eastern industrialregions.The effect of natural sources such as West African bushfires and Saharandust storms,was also reflected by transboundary dispersion patternsdue to wind systems in operation.Correlation analysis found that surface windspeed showed a statistically significant negative correlation with BC concentrationsduring all seasons,particularly March-May(r=-0.57,R^(2)=0.31)andJune-August(r=-0.51,R^(2)=0.24),indicating high winds favour BC dispersion.Specific humidity in addition to precipitation was moderately positivelycorrelated with BC,particularly during the September-November season(r=0.47,R^(2)=0.20),showing complex interactions between atmospheric moistureand aerosol lifecycles.Surface air temperature was most strongly seasonallycorrelated with BC during the short rains(r=0.55,R^(2)=0.29),showing thetwo-way effect of BC on atmospheric warming and radiative forcing.In short,the investigation indicates that BC concentrations over East Africa exhibit distinctspatial and temporal patterns driven by both human and natural processes.The statistically significant correlations with meteorological parametersprove the modulating role of BC in regional climate processes.Policymakersmust prioritize emission control actions targeted at biomass burning andurban pollution,and scientists must keep investigating high-resolution BCclimateinteractions using integrated ground and satellite observations to advanceclimate impact assessment in East Africa.
文摘遥感反演土壤水分(SM)产品越来越多地应用于农业、气象、水文等研究,而微波土壤水分数据产品的区域适用性分析是其合理使用的必要前提。使用MERRA-2(Modern Era Retrospective-analysis for Research and Applications,Version 2)模拟土壤水分为参考数据,运用传统统计方法(原始数据相关性、距平相关性、偏差以及无偏均方根差)和TC(Triple-Collocation)不确定性误差模型分析的方法,对亚洲区域2012年7月～2016年7月两种被动微波土壤水分SMOS-L3-SM(Soil Moisture and Ocean Salinity,L3)和AMSR2-LPRM-SM(The Advanced Microwave Scanning Radiometer 2,Land Parameter Retrieval Model Product)进行对比评估。结果表明:①空间上SMOS-L3较AMSR2-LPRM数据与参考数据MERRA-2土壤水分的相关性较好,表现为SMOS-L3-SM具有较好的空间连续性,且在亚洲大多数地区有较小的无偏均方根差;②湿季条件下遥感土壤水分与参考值的相关性比干季条件下的相关性更好,且干季出现高纬地区(约>55°)缺失值较多的情况;③两遥感土壤水分的TC误差呈现相似的分布,区域TC平均误差两者均为0.076 m^3/m^3。总之,SMOS-L3-SM和AMSR2-LPRM-SM在空间相关性及TC误差评价方面都具有合理性,为遥感土壤水分在农业、气象、水文等方面的应用提供参考。
