简介：Inthispaper,weproposeasimplifiedspatialchannelsoundingmethodbyutilizingbistaticsyntheticapertureradar(BiSAR)principles.DespitethedifferentdeploymentgeometriescomparedwithaconventionalBiSARsystem,thefeasibilityoftheapproachisestablishedby1)theproposedmethodachievesabetterspatialresolutionthanconventionaldirectionalchannelsoundersand2)reconstructionalgorithmsbasedontime-domainbackprojectioninconjunctionwithadigitalelevationmodelprovideagoodimagingperformanceandaresuitableforreconstructingthespatialdistributionofscatterers.Simulationsofahigh-speedrail(HSR)scenariodemonstratethattheestimatedpowerdelayprofiles(PDPs)andpowerangleprofiles(PAPs)areclosetotheactualvalues.

简介：MeteoroidsenteringtheEarth'satmospherecancreatemeteortrailirregularityseriouslydisturbingthebackgroundionosphere.AlthoughnumerousobservationsofmeteortrailirregularitieswereperformedwithVHF/UHFcoherentscatterradarsinthepast,nosimultaneousradarandopticalinstrumentswereemployedtoinvestigatethecharacteristicsofmeteortrailirregularityanditscorrespondingmeteoroid.ByinstallingmultiplevideocamerasneartheSanyaVHFradarsite,anobservationalcampaignwasconductedduringtheperiodfromNovember2016toFebruary2017.Atotalof242opticalmeteorswithsimultaneousnon-specularechoesbackscatteredfromtheplasmairregularitiesgeneratedinthecorrespondingmeteortrailswereidentified.Agoodagreementbetweentheangularpositionsofnon-specularechoesderivedfromtheSanyaradarinterferometerandthoseofopticalmeteorswasfound,validatingthattheradarsystemphaseoffsetshavebeenproperlycalibrated.TheresultsalsoverifytheinterferometrycapabilityofSanyaradarformeteortrailirregularityobservation.Thenon-specularechoeswithsimultaneousopticalmeteorsweredetectedatmagneticaspectanglesgreaterthan~78°.Basedonthemeteorvisualmagnitudeestimatedfromtheopticaldata,itwasfoundthattheradarnonspecularechoescorrespondingtobrightermeteorssurvivedforlongerduration.Thiscouldprovideobservationalevidenceforthesignificanceofmeteoroidmassonthedurationofmeteortrailirregularity.Ontheotherhand,thesimultaneousradarandvideocommon-volumeobservationsshowedthatthereweresomecaseswithopticalmeteorsbutwithoutradarnon-specularechoes.Onepossibilitycouldbethatsomeoftheopticalmeteorsappearedatextremelylowaltitudeswheremeteortrailirregularitiesrarelyoccur.

简介：热带气旋(TC)的几何特征以前在华南乍见陆地看用基于地面的雷达反射率被检验。中部、吝啬的眼睛区域与TC紧张减少，这被发现，除了严重台风范畴，并且眼睛尺寸与高度增加。眼睛尺寸的增加的率在上面的层是相对更大的。而且，在垂直方向的眼睛尺寸变化的比率不与TC相关紧张。没有关系在垂直方向和垂直的风在眼睛尺寸变化的比率之间被介绍砍。在在在某个水平的眼睛尺寸和眼睛尺寸的垂直变化之间的关系都没被发现，与另外的研究不一致。没有关系在眼睛尺寸和紧张趋势在垂直变化之间存在。主要从0.5～0.7的眼睛圆价值范围，和更强烈的TC通常有更圆形的眼睛。

简介：Twoassumptionsaretypicallymadewhenradarechosignalsfromprecipitationareanalyzedtodeterminethemicro-physicalparametersofraindrops:(1)theraindropsareassumedtobespherical;(2)multiplescatteringeffectsareignored.Radarcrosssections(RCS)areusuallycalculatedusingRayleigh'sscatteringequationwiththesimpleadditionmethodintheradarmeteorologicalequation.Weinvestigatetheextenttowhichconsiderationoftheeffectsofmultiplescatteringandofthenon-sphericalshapeswithinactualraindropswarmswouldresultinRCSvaluessignificantlydifferentfromthoseobtainedbyconventionalanalyticalmethods.First,weestablishsphericalandnon-sphericalraindropmodels,withGamma,JD,JT,andMPsizedistributions,respectively.WethenuseXFDTDsoftwaretocalculatetheradarcrosssectionsoftheaboveraindropmodelsattheS,C,XandKuradarbands.OurXFDTDresultsarethencomparedtoRCSvaluescalculatedbytheRayleighapproximationwithsimpleadditionmethods.Wefindthat:(1)RCSvaluescalculatedusingmultiplescatteringXFDTDsoftwarediffersignificantlyfromthosecalculatedbythesimpleadditionmethodatthesamebandforthesamemodel.Inparticular,forthesphericalraindropmodels,therelativedifferencesinRCSvaluesbetweenthemethodsrangefromamaximumof89.649%toaminimumof43.701%;forthenon-sphericalraindropmodels,therelativedifferencesrangefromamaximumof85.868%toaminimumof11.875%.(2)OurmultiplescatteringXFDTDresults,comparedtothoseobtainedfromtheRayleighformula,againdifferatallfoursizedistributions,byrelativeerrorsof169.522%,37.176%,216.455%,and63.428%,respectively.Whennonsphericaleffectsareconsidered,differencesinRCSvaluesbetweenourXFDTDcalculationsandRayleighcalculationsaresmaller;attheabovefoursizedistributionstherelativeerrorsare0.213%,0.171%,7.683%,and44.514%,respectively.RCSvaluescomputedbyconsideringmultiplescatteringandnon-sphericalparticleshapesarelargerthanRayleighRCS

简介：高周波的表面波浪雷达(HFSWR)和自动鉴定系统(AIS)是使用容器追踪的二个很重要的传感器。HFSWR能被用于在一个察觉区域追踪所有容器，当AIS通常被用来验证合作容器的信息时。因为从海喧嚷的干扰，为容器追踪采用单个频率的HFSWR可以遮住位于布拉格山峰的盲目地区的容器。在察觉频率分析变化为探讨这缺乏组成一个有效方法。由容器熔化追踪组成的一个解决方案用AIS校准的双频率的HFSWR数据被建议。因为不同系统的偏爱在HFSWR频率大小和AIS大小之间存在，AIS信息被用来估计并且改正HFSWR在每频率的系统的偏爱。首先，为合作容器的AIS点大小用一个日本胜利公司任务算法与HFSWR大小被联系。从合作容器的协会结果，在dualfrequencyHFSWR数据的系统的偏爱被估计并且改正。基于改正的双频率的HFSWR数据，然后，容器用一个双频率的熔化关节被追踪概率的数据协会(JPDA)-unscentedKalman过滤器(UKF)算法。用真实察觉数据的试验性的结果证明建议方法在在实时追踪容器是有效的并且能与追踪包含单个频率的数据的过程相比改进追踪的能力和精确性。

简介：ThisstudyinvestigatesclassificationanddiurnalvariationsoftheprecipitationechoesoverthecentralTibetanPlateaubasedontheobservationscollectedfromaC-bandvertically-pointingfrequency-modulatedcontinuous-wave(C-FMCW)radarduringtheThirdTibetanPlateauAtmosphericScientificExperiment(TIPEX-Ⅲ)2014-IntensiveObservationPeriod(2014-IOP).Theresultsshowthat51.32%oftheverticalprofileshavevalidechoeswithreflectivity>-10dBZ,and35.06%ofthevalidechoprofilesproduceprecipitationattheground(precipitationprofiles);stratiformprecipitationwithanevidentbright-bandsignature,weakconvectiveprecipitation,andstrongconvectiveprecipitationaccountfor52.03%,42.98%,and4.99%oftheprecipitationprofiles,respectively.About59.84%oftheprecipitationoccursintheafternoontomidnight,while40.16%oftheprecipitationwithweakerintensityisobservedinthenocturnalhoursandinthemorning.Diurnalvariationofoccurrencefrequencyofprecipitationshowsamajorpeakduring2100-2200LST(localsolartime)with59.02%beingthestratiformprecipitation;thesecondarypeakappearsduring1300-1400LSTwith59.71%beingtheweakconvectiveprecipitation;thestrongconvectiveprecipitationoccursmostly(81.83%)intheafternoonandeveningwithtwopeaksover1200-1300and1700-1800LST,respectively.Startingfromapproximately1100LST,precipitationechoesdevelopwithenhancedverticalairmotion,elevatedechotop,andincreasingradarreflectivity.Intenseupwardairmotionoccursmostfrequentlyin1700-1800LSTwithasecondarypeakin1100-1400LST,whilethetopsofprecipitationechoesandintenseupwardairmotionreachtheirhighestlevelsduring1600-1800LST.Theatmosphericconditionsintheearlymorningaredisadvantageousforconvectiveinitiationanddevelopment.Aroundnoon,theconvectiveavailablepotentialenergy(CAPE)increasesmarkedly,convectiveinhibition(CIN)isgenerallysmall,andasuper-dry-adiabaticlayerispresentnear