全球沙漠面积和粉尘排放量的新估算  

A new estimate of global desert area and quantity of dust emission

作　　者：吴会娟 鹿化煜[1] 王菁菁 陈瑶 崔梦淳[1,2] Huijuan Wu;Huayu Lu;Jingjing Wang;Yao Chen;Mengchun Cui(Frontiers Science Center for Critical Earth Material Cycling(Ministry of Education),School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China;Research Institute of Desertification,Chinese Academy of Forestry,Beijing 100091,China)

机构地区：[1]南京大学地理与海洋科学学院教育部关键地球物质循环前沿科学中心,南京210023 [2]中国林业科学研究院荒漠化研究所,北京100091

出　　处：《科学通报》2022年第9期860-871,共12页Chinese Science Bulletin

基　　金：国家自然科学基金(42021001,41920104005,41690111)资助。

摘　　要：沙漠是干旱半干旱地区最重要的地表景观,是粉尘排放的主要源区.确定全球沙漠边界、计算沙漠面积、估算沙漠的粉尘排放量对于定量评估沙漠对气候与环境的影响具有重要意义.利用中分辨率成像光谱仪(Moderate Resolution Imaging Spectroradiometer,MODIS)数据,结合支持向量机(Support Vector Machine,SVM)、试错法及目视解译技术提取了全球沙漠范围.对全球沙漠分区域进行面积和分类精度计算.利用地形、降水、蒸散、地表风速等数据对全球沙漠的环境变化进行分析.基于移动风蚀仪(Portable In-Situ Wind Erosion Laboratory,PI-SWERL)的观测数据,结合地表类型、土壤湿度和摩阻风速估算出全球沙漠的年粉尘排放量.研究表明,全球沙漠面积为~17.54×10^(6)km^(2),总体分类精度为92.37%.沙漠多分布于地形低于2000 m、降水量不足200 mm、全年风速为4~6 m/s的极端干旱和干旱地区.沙漠每年排放~1792.65 Tg粉尘(本文指PM_(10)),其中~1344.49 Tg粉尘堆积在陆地,~448.16 Tg粉尘沉降到海洋.此外,全球粉尘的年排放量具有显著的区域差异,粉尘排放量的高值区与粉尘源区具有很好的对应关系.利用遥感影像解译获得全球沙漠面积新数据,基于PI-SWERL观测数据估算全球沙漠的年粉尘排放量,其结果有利于评估全球尺度粉尘排放的气候效应.Deserts and their margins have long presented a challenge for human habitation,as an unstable and easily degraded environment.Deserts are the most important source of global dust emission,and the dust flux can be used as an index of land degradation and climate change,as well as a way to assess the dust’s own effects on global climate.In this study,we used the Moderate Resolution Imaging Spectroradiometer(MODIS)data,combing with Support Vector Machine(SVM)analysis,trial-and-error method and visual interpretation analyses,to extract the global and regional desert area,and analyze the accuracy of classification of the extracted desert area.We use data on topography,precipitation,evapotranspiration,and surface wind speed to characterize the environment of the world’s deserts,in order to explore the natural conditions that produce and accompany desert and produce a clear objective definition for the desert environment.Our results show that global desert area is~17.5×10^(6)km^(2),and the overall classificatory accuracy is 92%,according to the cross-checked by the multi-sources data calibrations.Globally,desert is mainly distributed in eastern hemisphere and northern hemisphere;North Africa and East Asia have the largest desert area.The classificatory accuracy of all individual regions is greater than 75%.Global desert,as characterized by our multi-faceted definition,is mainly distributed in low regions below 2000 m elevation,mean annual precipitation less than 200 mm,and annual wind speed is about 4–6 m/s.Based on our defined distribution of global deserts,we estimated dust emissions from those areas.Because dust emission is a small-scale,random process,it is necessary to collect field data of dust emission from typical landscape types,in order to describe dust emission and quantitatively assess their impact.We used data from the Portable In-Situ Wind Erosion Laboratory(PI-SWERL),which is a newly developed portable wind erosion instrument.Its observation data are in good agreement with the wind tunnel experimen

关 键 词：全球沙漠 粉尘排放量 中分辨率成像光谱仪 移动风蚀仪 PM_(10) 

分 类 号：P931.3[天文地球—自然地理学] X513[环境科学与工程—环境工程]