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
简介:1前言短波单边带数传系统是"9210"工程业务系统的重要组成部分,在"9210"工程实施过程中,我中心承担了短波单边带电台的技术验收工作,由于所采用的FT-80C型电台在业务使用中主要承担数传任务,因此对电台的部分技术指标有一定特殊要求:发射机载波频率误差≤10Hz、接收机调制接收带宽≥2.6kHz.
简介:基于2015年秋末冬初华北地区频繁出现的大范围重污染天气过程,利用无人直升机搭载的气溶胶采样装置和激光粒子计数器对北京顺义及房山地区近地面大气颗粒物进行探测,分析了重雾霾天气大气颗粒物的质量浓度和数浓度廓线及其分布特征。结果表明:北京地区重雾霾天气过程粒径小于1.0μm的气溶胶数浓度随高度变化不明显,粒径大于1.0μm的气溶胶数浓度随高度呈弱的减小趋势,说明重污染天气条件下近地面层大气颗粒物的粒子数相对稳定,亚微米级气溶胶数浓度较高,而粗粒子气溶胶数浓度较低。基于无人直升机搭载的气溶胶采样装置采集的气溶胶样品的质量浓度廓线表明,50m高度大气颗粒物质量浓度较高,最大浓度达700μg·m-3。