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1、中國科技論文在線http://www.paper.edu.cn#探索性GPS全球電離層TEC數(shù)據(jù)分析**秦昆，彭軍還（中國地質(zhì)大學(xué)（北京）土地科學(xué)技術(shù)學(xué)院，北京100083）5摘要：本文應(yīng)用空間統(tǒng)計(jì)學(xué)方法對IGS中心發(fā)布的全球電離層TEC數(shù)據(jù)進(jìn)行挖掘并做出分析。通過分析全球TEC數(shù)據(jù)的三維圖、頻率直方圖、半變異函數(shù)并計(jì)算均值、中位數(shù)、偏度、峰度等統(tǒng)計(jì)量，揭示TEC數(shù)據(jù)的空間分布呈非平穩(wěn)性；其全局趨勢用球諧函數(shù)描述，采用最小二乘擬合，根據(jù)殘差的統(tǒng)計(jì)特征確定9次球諧函數(shù)為最適合的全局趨勢；對去掉趨10勢后的殘差，通過半變異函數(shù)進(jìn)行
2、結(jié)構(gòu)分析，變異函數(shù)并不滿足平穩(wěn)性。通過經(jīng)度方向一次差分、緯度方向二次差分后的殘差分析，呈現(xiàn)幾乎無空間相關(guān)性的獨(dú)立噪聲空間過程，說明局部變化呈現(xiàn)非平穩(wěn)的三階偏隨機(jī)游動。差分后的誤差標(biāo)準(zhǔn)差從9.221TECU降低至1.175TECU。同時(shí)，用基于Delaunay三角網(wǎng)的自然鄰域方法對TEC數(shù)據(jù)進(jìn)行空間異常（斑點(diǎn)噪聲）探測，并分析其空間分布，得出TEC數(shù)據(jù)的斑點(diǎn)噪聲呈單調(diào)下降趨勢。對不同歷15元的TEC數(shù)據(jù)，可由同樣的混合模型描述，即電離層TEC呈現(xiàn)由球諧函數(shù)描述的全局趨勢，局部（或小尺度）變化呈現(xiàn)3階非平穩(wěn)偏隨機(jī)游動，并受服從單點(diǎn)
3、下降的斑點(diǎn)噪聲擾動。關(guān)鍵詞：地圖制圖學(xué)與地理信息工程；GPSTEC；變異函數(shù)；球諧函數(shù)；偏隨機(jī)游動；空間異常中圖分類號：P352.720ExploratoryGPSGlobalIonosphericTECanalysisQINKun,PENGJunhuan(SchoolofLandScienceandTechnology,ChinaUniversityofGeoscience(Beijing),Beijing100083)25Abstract:Inthispaperweapplyspatialstatisticsformini
4、ngandanalyzingglobalionosphericTECdatapublishedbyIGScenter.Thespatialnon-stationarypropertyoftheglobalTECisdiscoveredbyanalyzingthree-dimensionalmap,histogram,semivariogramandcountingthestatisticssuchasmean,median,skewness,kurtosis,etc.TheglobaltrendsurfaceofTECcanb
5、emodeledbytheSphericalHarmonicsand9-orderisthemostsuitablebycomparingresiduals’30statisticalcharacteristicsafterleast-squaresfitting.Afterremovingthetrend,thesemivarigramoftheresidualsdoesn’tshowstationarycharacter.Afterdoingsecond-orderdifferenceinlongitudinaldirec
6、tionandthendoingfirst-orderdifferenceinlatitudinaldirection,theresidualresultshowsthewhitenoiseproperty,andwhichindicatesthelocaland/orsmallscaleofvariationisathreeorderofpartialrandomwalkingspatialprocess.Andafterthreeorder’sdifference,35error’sstandarddeviationdec
7、reasedfrom9.221TECUto1.175TECU.Atthesametime,spatialoutliers(specklenoises)aredetectedonTECdatabyusingthenearestneighbormethodbasedontheDelaunaytriangulationanditsspatialstatisticaldistributionisfoundobeyingmonotonicdecreasing.FortheTECdataobtainedatdifferentepoch,i
8、tsspatialdistributioncanbedescribewiththefore-mentionedmixedmodelincludingglobaltrend,localvariationandabnomaly,that40is,theTECglobaltrend
