trend forecast趋势预测

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1、-3-AMOFSG/7-SNNo.24AMOFSG/7-SNNo.2415/8/08AERODROMEMETEOROLOGICALOBSERVATIONANDFORECASTSTUDYGROUP(AMOFSG)SEVENTHMEETINGMontréal,9to12September2008AgendaItem6:AerodromeforecastsTRENDFORECAST(PresentedbyKeesBlom)SUMMARYThispaperdescribesaproposalforanewwayofissuingaTRENDtypelandingfore

2、castbyusingtheexpectedprevailingweatherparametervaluesincombinationwiththetemporaryvariationsoftheparametervalues.1.INTRODUCTION1.1InmanyStatesuseismadeoftheTRENDtypelandingforecastaccordingtoAnnex3—MeteorologicalServiceforInternationalAirNavigation,para6.3.3:“trendforecastshallconsi

3、stofaconcisestatementoftheexpectedsignificantchangesinthemeteorologicalconditionsatthataerodrometobeappendedtoalocalroutineorlocalspecialreport,oraMETARorSPECI.Theperiodofvalidityofatrendforecastshallbe2hoursfromthetimeofthereportwhichformspartofthelandingforecast”.1.2WithAmendment74

4、toAnnex3itbecamepossibletoissueAUTOMETARduringopeninghoursofaerodromes.FurthermorethishasleadtoissuingAUTOlocalreportsandAUTOlocalspecialreportsatsomeaerodromesaswell.-3-AMOFSG/7-SNNo.241.DISCUSSION1.1Automatedweatherreportinginitselfprovestogeneratemorelocalspecialreports(and SPECI,

5、whenissued),sinceanautomatedsystemwillstrictlyadheretoregulations,wherehumanobserverstendtoanticipatechangesandareabletocombinechangeswhichoccurshortlyaftereachotherintoonereport.1.2PreparingTRENDforecastswitheverynewreporthasalwaystakenalotofeffortfromaviationforecasters,evenmorewhe

6、retheyareprovidingTRENDforecastsforseveralaerodromesfromacentralizedforecastoffice.1.3TRENDforecastsaccordingtothepresentrecommendationhavetoprovide………theexpectedsignificantchangesinthemeteorologicalconditions…...Especiallyinweathersituationswithrapidlychangingconditionsthisresultsin

7、manydifferentTRENDforecasts,whiletheprevailingweatherconditionsdohardlychange.Examples:METAREHAM041425Z14011KT4000SHRAFEW034CBBKN04005/01Q1007BECMG9999NSW=SPECIEHAM041435Z14011KT9999FEW034BKN04005/01Q1007TEMPO14017G28KT4000SHRASCT030CB=SPECIEHAM041435Z15015G25KT4000SHRAFEW032CBBKN040

8、05/01Q1007BE