简介:Inthisstudy,about220satelliteimagesbetween2000and2012wereobtainedfromFY-series,MODIS,CBERS,HJ-1AandHJ-1BtoestimatetheimpactofduststormsontheSouthYellowSea(SYS),whichserveasanimportantsourceofparticlesthere.Theanalyzingresultsfromtheimagessupportatotaloccurrenceof88duststorms(includingthelocally-generateddustyweather)thataffectedtheSYSduring2000–2012.Theannualoccurrencewasabout4–10times(10timesin2000and2004;fourtimesin2009and2012),predominantlyinMarch(29%),April(33%)andMay(22%).Bymappingthedistributionoftheirfrequency,theduststormsinfluencingtheSYSwerefoundprimarilymovingfromthenorthwest(39times,44.3%)andwest(37times,42%)tothestudyregionwithonly11duststorms(12.5%)comingfromthenorthand1duststorm(1%)fromthesouthwest.Weestimatedthatanannualamountof0.5–3.5milliontonsofsedimentparticleswasbroughttotheSYSbytheduststormsduring2000–2012.
简介:在国际标准电子海图显示信息系统(ECDIS)中,信息的表达模型是独立于数据存储的。根据空间数据处理的特点和可视化的基本技术,矢量数据的几何图形表示方法通常包括点数据表示、线数据表示和面数据表示等三种。介绍了关于点、线、面基本图元的符号化问题。