This paper presents an attempt at assimilating clear-sky FY-4A Advanced Geosynchronous Radiation Imager(AGRI)radiances from two water vapor channels for the prediction of three landfalling typhoon events over the West...This paper presents an attempt at assimilating clear-sky FY-4A Advanced Geosynchronous Radiation Imager(AGRI)radiances from two water vapor channels for the prediction of three landfalling typhoon events over the West Pacific Ocean using the 3DVar data assimilation(DA)method along with the WRF model.A channel-sensitive cloud detection scheme based on the particle filter(PF)algorithm is developed and examined against a cloud detection scheme using the multivariate and minimum residual(MMR)algorithm and another traditional cloud mask–dependent cloud detection scheme.Results show that both channel-sensitive cloud detection schemes are effective,while the PF scheme is able to reserve more pixels than the MMR scheme for the same channel.In general,the added value of AGRI radiances is confirmed when comparing with the control experiment without AGRI radiances.Moreover,it is found that the analysis fields of the PF experiment are mostly improved in terms of better depicting the typhoon,including the temperature,moisture,and dynamical conditions.The typhoon track forecast skill is improved with AGRI radiance DA,which could be explained by better simulating the upper trough.The impact of assimilating AGRI radiances on typhoon intensity forecasts is small.On the other hand,improved rainfall forecasts from AGRI DA experiments are found along with reduced errors for both the thermodynamic and moisture fields,albeit the improvements are limited.展开更多
为加强多源闪电数据在干旱区的融合应用,利用新疆民航三维地基闪电探测系统(3-Dimension Lightning Location System,3-DLLS)、全球闪电定位网(World-Wide Lightning Location Network,WWLLN)和气象部门ADTD(Advanced Time of Arrival a...为加强多源闪电数据在干旱区的融合应用,利用新疆民航三维地基闪电探测系统(3-Dimension Lightning Location System,3-DLLS)、全球闪电定位网(World-Wide Lightning Location Network,WWLLN)和气象部门ADTD(Advanced Time of Arrival and Direction System)、FY-4A闪电成像仪(Lightning Mapping Imager,LMI)等多源闪电资料,针对新疆地区2019年11次典型雷暴过程,开展FY-4A LMI探测性能的初步评估,并结合FY-4A云顶温度(Cloud Top Temperature,CTT)资料,详细分析2019年7月21日强雷暴过程的闪电特征,探寻CTT与闪电活动的相关关系。结论如下:(1)FY-4A LMI闪电“组”(LMI Group,LMIG)数量约为3-DLLS的1/5、WWLLN的1.02倍、ADTD的1/3。白天,在太阳背景光影响下FY-4A LMI的探测效率有所下降,即使日出后雷暴系统有所加强,但LMIG数量并无增加趋势。(2)在2019年7月21日强雷暴过程中,3-DLLS探测的闪电时空分布与ADTD重合度较高,而WWLLN的闪电定位与前两者在时空上存在一定偏差,这主要是各系统的探测原理(WWLLN主要探测的是强地闪,ADTD主要监测地闪回击,而3-DLLS探测的是全闪)及测站布局和数量不同所致。(3)在强雷暴过程不同发展阶段,闪电发生区域的FY-4A CTT值差异较大,初始阶段、旺盛阶段和消散阶段闪电区域对应的CTT值分别为260~280 K、230~240 K和240~260 K。展开更多
基金primarily supported by the Chinese National Natural Science Foundation of China(Grant No. G42192553)Open Fund of Fujian Key Laboratory ofSevere Weather and Key Laboratory of Straits Severe Weather(Grant No. 2023KFKT03)+6 种基金the Open Project Fund of China Meteorological Administration Basin Heavy Rainfall Key Laboratory(Grant No. 2023BHR-Y20)the Open Fund of the State Key Laboratory of Remote Sensing Science (Grant No. OFSLRSS202321)the Program of Shanghai Academic/Technology Research Leader(Grant No. 21XD1404500)the Shanghai Typhoon Research Foundation (Grant No. TFJJ202107)the Chinese National Natural Science Foundation of China (Grant No. G41805016)the National Meteorological Center Foundation (Grant No. FY-APP-2021.0207)the High Performance Computing Center of Nanjing University of Information Science&Technology for their support of this work
文摘This paper presents an attempt at assimilating clear-sky FY-4A Advanced Geosynchronous Radiation Imager(AGRI)radiances from two water vapor channels for the prediction of three landfalling typhoon events over the West Pacific Ocean using the 3DVar data assimilation(DA)method along with the WRF model.A channel-sensitive cloud detection scheme based on the particle filter(PF)algorithm is developed and examined against a cloud detection scheme using the multivariate and minimum residual(MMR)algorithm and another traditional cloud mask–dependent cloud detection scheme.Results show that both channel-sensitive cloud detection schemes are effective,while the PF scheme is able to reserve more pixels than the MMR scheme for the same channel.In general,the added value of AGRI radiances is confirmed when comparing with the control experiment without AGRI radiances.Moreover,it is found that the analysis fields of the PF experiment are mostly improved in terms of better depicting the typhoon,including the temperature,moisture,and dynamical conditions.The typhoon track forecast skill is improved with AGRI radiance DA,which could be explained by better simulating the upper trough.The impact of assimilating AGRI radiances on typhoon intensity forecasts is small.On the other hand,improved rainfall forecasts from AGRI DA experiments are found along with reduced errors for both the thermodynamic and moisture fields,albeit the improvements are limited.
文摘为加强多源闪电数据在干旱区的融合应用,利用新疆民航三维地基闪电探测系统(3-Dimension Lightning Location System,3-DLLS)、全球闪电定位网(World-Wide Lightning Location Network,WWLLN)和气象部门ADTD(Advanced Time of Arrival and Direction System)、FY-4A闪电成像仪(Lightning Mapping Imager,LMI)等多源闪电资料,针对新疆地区2019年11次典型雷暴过程,开展FY-4A LMI探测性能的初步评估,并结合FY-4A云顶温度(Cloud Top Temperature,CTT)资料,详细分析2019年7月21日强雷暴过程的闪电特征,探寻CTT与闪电活动的相关关系。结论如下:(1)FY-4A LMI闪电“组”(LMI Group,LMIG)数量约为3-DLLS的1/5、WWLLN的1.02倍、ADTD的1/3。白天,在太阳背景光影响下FY-4A LMI的探测效率有所下降,即使日出后雷暴系统有所加强,但LMIG数量并无增加趋势。(2)在2019年7月21日强雷暴过程中,3-DLLS探测的闪电时空分布与ADTD重合度较高,而WWLLN的闪电定位与前两者在时空上存在一定偏差,这主要是各系统的探测原理(WWLLN主要探测的是强地闪,ADTD主要监测地闪回击,而3-DLLS探测的是全闪)及测站布局和数量不同所致。(3)在强雷暴过程不同发展阶段,闪电发生区域的FY-4A CTT值差异较大,初始阶段、旺盛阶段和消散阶段闪电区域对应的CTT值分别为260~280 K、230~240 K和240~260 K。
