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简介：开展10-30d延伸期天气预报对于气象防灾减灾具有重要意义,也是填补短中期天气预报和短期气候预测之间的时间缝隙、构建完备性预报体系的必然要求。本文从延伸期天气预报的预报对象、基本方法和相关原理以及国内外业务实践3方面回顾了延伸期预报的科学进展和业务现状,从数值方法、大气低频信号演变方法和数理统计方法3个角度比较分析了延伸期预报的各种主流方法,详细探讨了各种方法的优势和不足,在此基础上对目前延伸期预报领域存在的问题进行了梳理和总结。

简介：BasedontheNCEP/NCARreanalysisdataandtheobservedprecipitationdatainthesouthofChinafrom1958to2000,theimpactof30to60dayoscillationofatmosphericheatsourcesonthedroughtandfloodeventsinJuneinthesouthofChinaisdiscussed.Duringtheflood(drought)events,thereexistsananomalouslow-frequencyanticyclone(cyclone)atthelowlevelofthetroposphereovertheSouthChinaSeaandthenorthwesternPacific,accompaniedwithanomalouslow-frequencyheatsinks(heatsources),whilethereexistsananomalouslow-frequencycyclone(anticyclone)withanomalousheatsources(sinks)overtheareafromthesouthofChinatothesouthofJapan.Onaverage,thephaseevolutionofthelow-frequencyindroughteventsis7to11daysaheadofthatinfloodeventsinMaytoJuneinthesouthofChina.Infloodevents,low-frequencyheatsourcesandcyclonesarepropagatednorthwardfromthesouthernSouthChinaSea,northwestwardfromthewarmpoolofthewesternPacificandwestwardfromthenorthwesternPacificaround140°E,whichhaveveryimportantimpactontheabundantrainfallinJuneinthesouthofChina.However,indroughtevents,thenorthwardpropagationsofthelow-frequencyheatsourcesandcyclonesfromtheSouthChinaSeaanditsvicinityareratherlatecomparedwiththoseinfloodevents,andthereisnoobviouswestwardpropagationoftheheatsourcesfromthenorthwesternPacific.Thetimingofthelow-frequencyheatsourcepropagationhasremarkableimpactontheJunerainfallinthesouthofChina.

简介：Daily850-hPameridionalwindfieldsinEastAsiafromMarchtoSeptember2002wereusedtoestablishamodeloftheprincipaloscillationpattern(POP).Thismodelwasthenusedtoconductindependentextended-rangeforecastsoftheprincipaltemporalandspatialvariationsinthelow-frequencymeridionalwindfieldonatimescaleof20-30days.ThesevariationsaffecttheoccurrenceofheavyprecipitationeventsinthelowerreachesoftheYangtzeRivervalley(LYRV).Theresultsof135forecastexperimentsduringthesummerhalfyearshowthatthepredictedandobservedanomaliesarestronglycorrelatedataleadtimeof20days(meancorrelationgreaterthan0.50).Thisstrongcorrelationindicatesthatthemodeliscapableofaccuratelyforecastingthelow-frequencyvariationsinmeridionalwindthatcorrespondedtothe3heavyprecipitationeventsintheLYRVduringthesummerof2002.Furtherforecastexperimentsbasedondatafrommultipleyearswithsignificant20-30-dayoscillationsshowthatthesepredictionmodesareeffectivetoolsforforecastingthespace-timeevolutionofthelow-frequencycirculation.ThesefindingsofferpotentialforimprovingtheaccuracyofforecastsofheavyprecipitationovertheLYRVatleadtimesof3-4weeks.

简介：基于30省区CGE模型,模拟分析了碳排放许可的强度分配标准对我国区域协调发展的影响。结果表明：按行业属性设定强度分配标准会加剧区域经济发展不平衡状况;按区域经济发展水平设定强度分配标准,对区域协调发展的影响较小,但会对高排放行业造成较大的冲击。中央政府基于强度分配标准,参考区域经济发展水平,将碳排放许可分配到各个省份,然后各个省份再参考行业特点将碳排放许可分配给机制覆盖行业的实体或排放源,这样的两阶段分配结构是较为现实的、具有可操作性的政策选择。