High spatiotemporal resolution infrared radiances from FY-4A/AGRI(Advanced Geostationary Radiation Imager)can provide crucial information for rapidly developing severe convective weather.This study established a symme...High spatiotemporal resolution infrared radiances from FY-4A/AGRI(Advanced Geostationary Radiation Imager)can provide crucial information for rapidly developing severe convective weather.This study established a symmetric observation error model that differentiates between land and sea for FY-4A/AGRI all-sky assimilation,developed an all-sky assimilation scheme for FY-4A/AGRI based on hydrometeor control variables,and investigated the impacts of all-sky FY-4A/AGRI water vapor channels at different altitudes and rapid-update assimilation at different frequencies on the assimilation and forecasting of a severe convective weather event.Results show that simultaneous assimilation of two water vapor channels can enhance precipitation forecasts compared to single-channel assimilation,which is mainly attributable to a more accurate analysis of water vapor and hydrometeor information.Experiments with different assimilation frequencies demonstrate that the hourly assimilation frequency,compared to other frequencies,incorporates the high-frequency information from AGRI while reducing the impact of spurious oscillations caused by excessively high-frequency assimilation.This hourly assimilation frequency reduces the incoordination among thermal,dynamical,and water vapor conditions caused by excessively fast or slow assimilation frequencies,thus improving the forecast accuracy compared to other frequencies.展开更多
风云四号B星(FY-4B)是中国最新一代的静止轨道气象卫星,其资料具有更高的时空分辨率。为了进一步推进FY-4B云导风资料在数值模式中的应用,以FY-4B云导风资料为主要研究对象,结合FY-4A云导风资料进行对比,首先分析了其观测误差的垂直分...风云四号B星(FY-4B)是中国最新一代的静止轨道气象卫星,其资料具有更高的时空分辨率。为了进一步推进FY-4B云导风资料在数值模式中的应用,以FY-4B云导风资料为主要研究对象,结合FY-4A云导风资料进行对比,首先分析了其观测误差的垂直分布情况,以此更新WRFDA(Weather Research and Forecasting model Data Assimilation system)同化系统中默认观测误差,随后进一步探究了云导风资料同化对2022年台风“梅花”的预报影响。研究结果表明:FY-4B云导风资料U、V分量的观测误差整体上小于FY-4A;同化FY-4A云导风资料后,模拟的台风路径逐渐偏西;而同化FY-4B云导风资料使得台风中心动力场信息更加完善,分析场对流层中高层西风增强,预报的台风路径更接近实况;相较于同化FY-4A云导风资料,同化FY-4B云导风资料对降水预报的改善效果更好。展开更多
Accurate estimates of land surface characteristic parameters and turbulent heat fluxes play an important role in the understanding of land-atmosphere interaction. In this study, Fengyun-4A (FY-4A) Advanced Geostationa...Accurate estimates of land surface characteristic parameters and turbulent heat fluxes play an important role in the understanding of land-atmosphere interaction. In this study, Fengyun-4A (FY-4A) Advanced Geostationary Radiation Imager (AGRI) satellite data and the China Land Data Assimilation System (CLDAS) meteorological forcing dataset CLDAS-V2.0 were applied for the retrieval of broadband albedo, land surface temperature (LST), radiation flux components, and turbulent heat fluxes over the Tibetan Plateau (TP). The FY-4A/AGRI and CLDAS-V2.0 data from 12 March 2018 to 30 April 2018 were first used to estimate the hourly turbulent heat fluxes over the TP. The time series data of in-situ measurements from the Tibetan Observation and Research Platform were divided into two halves-one for developing retrieval algorithms for broadband albedo and LST based on FY-4A, and the other for the cross validation. Results show the root-mean-square errors (RMSEs) of the FY-4A retrieved broadband albedo and LST were 0.0309 and 3.85 K, respectively, which verifies the applicability of the retrieval method. The RMSEs of the downwelling/upwelling shortwave radiation flux and downwelling/upwelling longwave radiation flux were 138.87/32.78 W m^(−2) and 51.55/17.92 W m^(−2), respectively, and the RMSEs of net radiation flux, sensible heat flux, and latent heat flux were 58.88 W m^(−2), 82.56 W m^(−2) and 72.46 W m^(−2), respectively. The spatial distributions and diurnal variations of LST and turbulent heat fluxes were further analyzed in detail.展开更多
Assimilation of the Advanced Geostationary Radiance Imager(AGRI)clear-sky radiance in a regional model is performed.The forecasting effectiveness of the assimilation of two water vapor(WV)channels with conventional ob...Assimilation of the Advanced Geostationary Radiance Imager(AGRI)clear-sky radiance in a regional model is performed.The forecasting effectiveness of the assimilation of two water vapor(WV)channels with conventional observations for the“21·7”Henan extremely heavy rainfall is analyzed and compared with a baseline test that assimilates only conventional observations in this study.The results show that the 24-h cumulative precipitation forecast by the assimilation experiment with the addition of the AGRI exceeds 500 mm,compared to a maximum value of 532.6 mm measured by the national meteorological stations,and that the location of the maximum precipitation is consistent with the observations.The results for the short periods of intense precipitation processes are that the simulation of the location and intensity of the 3-h cumulative precipitation is also relatively accurate.The analysis increment shows that the main difference between the two sets of assimilation experiments is over the ocean due to the additional ocean observations provided by FY-4A,which compensates for the lack of ocean observations.The assimilation of satellite data adjusts the vertical and horizontal wind fields over the ocean by adjusting the atmospheric temperature and humidity,which ultimately results in a narrower and stronger WV transport path to the center of heavy precipitation in Zhengzhou in the lower troposphere.Conversely,the WV convergence and upward motion in the control experiment are more dispersed;therefore,the precipitation centers are also correspondingly more dispersed.展开更多
基金supported by the National Key R&D Program of China(Grant No.2022YFC3080500)the National Natural Science Foundation of China(Grant Nos.U2142208,42475158,and 42105149)the High-Performance Computing Center of Nanjing University of Information Science&Technology for supporting this work。
文摘High spatiotemporal resolution infrared radiances from FY-4A/AGRI(Advanced Geostationary Radiation Imager)can provide crucial information for rapidly developing severe convective weather.This study established a symmetric observation error model that differentiates between land and sea for FY-4A/AGRI all-sky assimilation,developed an all-sky assimilation scheme for FY-4A/AGRI based on hydrometeor control variables,and investigated the impacts of all-sky FY-4A/AGRI water vapor channels at different altitudes and rapid-update assimilation at different frequencies on the assimilation and forecasting of a severe convective weather event.Results show that simultaneous assimilation of two water vapor channels can enhance precipitation forecasts compared to single-channel assimilation,which is mainly attributable to a more accurate analysis of water vapor and hydrometeor information.Experiments with different assimilation frequencies demonstrate that the hourly assimilation frequency,compared to other frequencies,incorporates the high-frequency information from AGRI while reducing the impact of spurious oscillations caused by excessively high-frequency assimilation.This hourly assimilation frequency reduces the incoordination among thermal,dynamical,and water vapor conditions caused by excessively fast or slow assimilation frequencies,thus improving the forecast accuracy compared to other frequencies.
文摘风云四号B星(FY-4B)是中国最新一代的静止轨道气象卫星,其资料具有更高的时空分辨率。为了进一步推进FY-4B云导风资料在数值模式中的应用,以FY-4B云导风资料为主要研究对象,结合FY-4A云导风资料进行对比,首先分析了其观测误差的垂直分布情况,以此更新WRFDA(Weather Research and Forecasting model Data Assimilation system)同化系统中默认观测误差,随后进一步探究了云导风资料同化对2022年台风“梅花”的预报影响。研究结果表明:FY-4B云导风资料U、V分量的观测误差整体上小于FY-4A;同化FY-4A云导风资料后,模拟的台风路径逐渐偏西;而同化FY-4B云导风资料使得台风中心动力场信息更加完善,分析场对流层中高层西风增强,预报的台风路径更接近实况;相较于同化FY-4A云导风资料,同化FY-4B云导风资料对降水预报的改善效果更好。
基金This research was jointly funded by the Second Tibetan Plateau Scientific Expedition and Research Pro-gram(Grant No.2019QZKK010305)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA20060101)+2 种基金the National Natural Science Foundation of China(Grant Nos.41875031,91837208,41522501 and 41275028)the Chinese Academy of Sciences Basic Frontier Sci-ence Research Program from 0 to 1 Original Innovation Project(Grant No.ZDBS-LY-DQC005-01)the Chinese Academy of Sciences(Grant No.QYZDJ-SSW-DQC019).
文摘Accurate estimates of land surface characteristic parameters and turbulent heat fluxes play an important role in the understanding of land-atmosphere interaction. In this study, Fengyun-4A (FY-4A) Advanced Geostationary Radiation Imager (AGRI) satellite data and the China Land Data Assimilation System (CLDAS) meteorological forcing dataset CLDAS-V2.0 were applied for the retrieval of broadband albedo, land surface temperature (LST), radiation flux components, and turbulent heat fluxes over the Tibetan Plateau (TP). The FY-4A/AGRI and CLDAS-V2.0 data from 12 March 2018 to 30 April 2018 were first used to estimate the hourly turbulent heat fluxes over the TP. The time series data of in-situ measurements from the Tibetan Observation and Research Platform were divided into two halves-one for developing retrieval algorithms for broadband albedo and LST based on FY-4A, and the other for the cross validation. Results show the root-mean-square errors (RMSEs) of the FY-4A retrieved broadband albedo and LST were 0.0309 and 3.85 K, respectively, which verifies the applicability of the retrieval method. The RMSEs of the downwelling/upwelling shortwave radiation flux and downwelling/upwelling longwave radiation flux were 138.87/32.78 W m^(−2) and 51.55/17.92 W m^(−2), respectively, and the RMSEs of net radiation flux, sensible heat flux, and latent heat flux were 58.88 W m^(−2), 82.56 W m^(−2) and 72.46 W m^(−2), respectively. The spatial distributions and diurnal variations of LST and turbulent heat fluxes were further analyzed in detail.
基金supported by the National Key R&D Program of China(Grant Nos.2017YFC1501803 and 2017YFC1502102)。
文摘Assimilation of the Advanced Geostationary Radiance Imager(AGRI)clear-sky radiance in a regional model is performed.The forecasting effectiveness of the assimilation of two water vapor(WV)channels with conventional observations for the“21·7”Henan extremely heavy rainfall is analyzed and compared with a baseline test that assimilates only conventional observations in this study.The results show that the 24-h cumulative precipitation forecast by the assimilation experiment with the addition of the AGRI exceeds 500 mm,compared to a maximum value of 532.6 mm measured by the national meteorological stations,and that the location of the maximum precipitation is consistent with the observations.The results for the short periods of intense precipitation processes are that the simulation of the location and intensity of the 3-h cumulative precipitation is also relatively accurate.The analysis increment shows that the main difference between the two sets of assimilation experiments is over the ocean due to the additional ocean observations provided by FY-4A,which compensates for the lack of ocean observations.The assimilation of satellite data adjusts the vertical and horizontal wind fields over the ocean by adjusting the atmospheric temperature and humidity,which ultimately results in a narrower and stronger WV transport path to the center of heavy precipitation in Zhengzhou in the lower troposphere.Conversely,the WV convergence and upward motion in the control experiment are more dispersed;therefore,the precipitation centers are also correspondingly more dispersed.
