In this study,we derived atmospheric profiles of temperature,moisture,and ozone,along with surface emissivity,skin temperature,and surface pressure,from infrared-sounder radiances under clear sky (cloudless) condition...In this study,we derived atmospheric profiles of temperature,moisture,and ozone,along with surface emissivity,skin temperature,and surface pressure,from infrared-sounder radiances under clear sky (cloudless) condition.Clouds were detected objectively using the Atmospheric Infrared Sounder under a relatively low spatial resolution and cloud-mask information from the Moderate Resolution Imaging Spectroradiometer under a high horizontal resolution;this detection was conducted using space matching.Newton’s nonlinear physical iterative solution technique is applied to the radiative transfer equation (RTE) to retrieve temperature profiles,relative humidity profiles,and surface variables simultaneously.This technique is carried out by using the results of an eigenvector regression retrieval as the background profile and using corresponding iterative forms for the weighting functions of temperature and water-vapor mixing ratio.The iterative forms are obtained by applying the variational principle to the RTE.We also compared the retrievals obtained with different types of observations.The results show that the retrieved atmospheric sounding profile has great superiority over other observations by accuracy and resolution.Retrieved profiles can be used to improve the initial conditions of numerical models and used in areas where conventional observations are sparse,such as plateaus,deserts,and seas.展开更多
微波辐射计资料具有高时空密度优势,但受辐射原理限制,使用地域不同,厂家工艺及型号差异影响,导致数据质量存疑,使其在气象业务工作中的应用受到限制。对辐射计数据的可靠性和可用性进行全面研究,充分发挥其应用优势,服务于气象业务和研...微波辐射计资料具有高时空密度优势,但受辐射原理限制,使用地域不同,厂家工艺及型号差异影响,导致数据质量存疑,使其在气象业务工作中的应用受到限制。对辐射计数据的可靠性和可用性进行全面研究,充分发挥其应用优势,服务于气象业务和研究,具有重要的现实意义。利用2014年7、8月爱尔达HTG-3型微波辐射计探测数据,参考北京南郊观象台气球探空资料,采用时间同步和高度同步方法,进行辐射计资料的定量分析。结果表明:(1)温湿基础数据的相关性整体表现为低层优于高层,温度在300 h Pa以下各标准层的相关系数均>0.80,500 h Pa以下各标准层露点和水汽密度的相关系数均>0.75;(2)700 h Pa以下各标准层温度、1000 h Pa露点和水汽密度与探空值基本相当,可直接定量使用,其余数据则需进行订正后使用;(3)除雷暴天外700 h Pa以下各标准层温度,1000 h Pa的露点以及晴、阴、雨天1000 h Pa的水汽密度与探空值基本一致,可替代使用,其余数据需进行订正后使用;(4)温度廓线和水汽密度廓线的一致性较好,露点廓线较差,温度廓线按优排序为晴、雾、阴、雨、雷暴天,露点廓线按优排序则正好相反;(5)辐射计探测得到的各气象要素随高度演变的廓线存在平滑现象;(6)除EL外的重要层结高度,VT、TT及SI等的相对误差在±10%左右,基本可以定量使用外,其余参数均需视情况进行订正或根据辐射计自身特点重新推导对应参量的计算公式。展开更多
The influences of Tropical Rainfall Measuring Mission （TRMM） precipitation products on the structure and underlying physics of intraseasonal oscillation （ISO） are investigated with the U.S. National Aeronautics an...The influences of Tropical Rainfall Measuring Mission （TRMM） precipitation products on the structure and underlying physics of intraseasonal oscillation （ISO） are investigated with the U.S. National Aeronautics and Space Administration Goddard Earth Observing System model version 3 （GEOS-3） data assimilation system （DAS）. The strong ISO phase in the 1998 summer is apparently located in the Asian monsoon region and the east equatorial Pacific region. The eastward propagation is a dominant feature for the tropical ISO at 20 to 30-day oscillation while the northeastward propagation is the salient ISO at 30 to 60-day oscillation over the 10~N to 25~N belt region. It appears that the Kelvin wave structure is for the tropical 20 to 30-day oscillation. The tropical 30 to 60-day oscillation has the characteristics of the Kelvin-Rossby wave. The impact of satellite-derived precipitation （and its associated latent heating） on the ISO intensity is limited in the GEOS-3 assimilation system. However, its impact on the ISO spatial structures is obvious. Overall, the results demonstrate a better eastward propagation and a northward propagation of ISO with the TRMM precipitation simulation, indicating that latent heating is very important in exciting the equatorial ISO. Key words： 20 to 30-day oscillation; 30 to 60-day oscillation; GEOS data assimilation system; Kelvin wave; TRMM precipitation展开更多
Direct assimilation of cloud-affected microwave brightness temperatures from AMSU-A into the GSI three-dimensional variational （3D-Var） assimilation system is preliminarily studied in this paper. A combination of cl...Direct assimilation of cloud-affected microwave brightness temperatures from AMSU-A into the GSI three-dimensional variational （3D-Var） assimilation system is preliminarily studied in this paper. A combination of cloud microphysics param- eters retrieved by the 1D-Var algorithm （including vertical profiles of cloud liquid water content, ice water content, and rain water content） and atmospheric state parameters from objective analysis fields of an NWP model are used as background fields. Three cloud microphysics parameters （cloud liquid water content, ice water content, and rain water content） are ap- plied to the control variable. Typhoon Halong （2014） is selected as an example. The results show that direct assimilation of cloud-affected AMSU-A observations can effectively adjust the structure of large-scale temperature, humidity and wind anal- ysis fields due to the assimilation of more AMSU-A observations in typhoon cloudy areas, especially typhoon spiral cloud belts. These adjustments, with temperatures increasing and humidities decreasing in the movement direction of the typhoon, bring the forecasted typhoon moving direction closer to its real path. The assimilation of cloud-affected satellite microwave brightness temperatures can provide better analysis fields that are more similar to the actual situation. Furthermore, typhoon prediction accuracy is improved using these assimilation analysis fields as the initial forecast fields in NWP models.展开更多
基金project of the Ministry of Sciences and Technology of the People’s Republic of China (GYHY200706020)projects of National Natural Science Foundation of China ((40975034, 40505009)project of State Key Laboratory of Severe Weather (2008LASW-A01)
文摘In this study,we derived atmospheric profiles of temperature,moisture,and ozone,along with surface emissivity,skin temperature,and surface pressure,from infrared-sounder radiances under clear sky (cloudless) condition.Clouds were detected objectively using the Atmospheric Infrared Sounder under a relatively low spatial resolution and cloud-mask information from the Moderate Resolution Imaging Spectroradiometer under a high horizontal resolution;this detection was conducted using space matching.Newton’s nonlinear physical iterative solution technique is applied to the radiative transfer equation (RTE) to retrieve temperature profiles,relative humidity profiles,and surface variables simultaneously.This technique is carried out by using the results of an eigenvector regression retrieval as the background profile and using corresponding iterative forms for the weighting functions of temperature and water-vapor mixing ratio.The iterative forms are obtained by applying the variational principle to the RTE.We also compared the retrievals obtained with different types of observations.The results show that the retrieved atmospheric sounding profile has great superiority over other observations by accuracy and resolution.Retrieved profiles can be used to improve the initial conditions of numerical models and used in areas where conventional observations are sparse,such as plateaus,deserts,and seas.
文摘微波辐射计资料具有高时空密度优势,但受辐射原理限制,使用地域不同,厂家工艺及型号差异影响,导致数据质量存疑,使其在气象业务工作中的应用受到限制。对辐射计数据的可靠性和可用性进行全面研究,充分发挥其应用优势,服务于气象业务和研究,具有重要的现实意义。利用2014年7、8月爱尔达HTG-3型微波辐射计探测数据,参考北京南郊观象台气球探空资料,采用时间同步和高度同步方法,进行辐射计资料的定量分析。结果表明:(1)温湿基础数据的相关性整体表现为低层优于高层,温度在300 h Pa以下各标准层的相关系数均>0.80,500 h Pa以下各标准层露点和水汽密度的相关系数均>0.75;(2)700 h Pa以下各标准层温度、1000 h Pa露点和水汽密度与探空值基本相当,可直接定量使用,其余数据则需进行订正后使用;(3)除雷暴天外700 h Pa以下各标准层温度,1000 h Pa的露点以及晴、阴、雨天1000 h Pa的水汽密度与探空值基本一致,可替代使用,其余数据需进行订正后使用;(4)温度廓线和水汽密度廓线的一致性较好,露点廓线较差,温度廓线按优排序为晴、雾、阴、雨、雷暴天,露点廓线按优排序则正好相反;(5)辐射计探测得到的各气象要素随高度演变的廓线存在平滑现象;(6)除EL外的重要层结高度,VT、TT及SI等的相对误差在±10%左右,基本可以定量使用外,其余参数均需视情况进行订正或根据辐射计自身特点重新推导对应参量的计算公式。
基金Qing Lan Project and a Special Public Sector Research (GYHY200806009)The second author was funded by the NASA Global Water and Energy Cycle project with a grant NNG04G098G
文摘The influences of Tropical Rainfall Measuring Mission （TRMM） precipitation products on the structure and underlying physics of intraseasonal oscillation （ISO） are investigated with the U.S. National Aeronautics and Space Administration Goddard Earth Observing System model version 3 （GEOS-3） data assimilation system （DAS）. The strong ISO phase in the 1998 summer is apparently located in the Asian monsoon region and the east equatorial Pacific region. The eastward propagation is a dominant feature for the tropical ISO at 20 to 30-day oscillation while the northeastward propagation is the salient ISO at 30 to 60-day oscillation over the 10~N to 25~N belt region. It appears that the Kelvin wave structure is for the tropical 20 to 30-day oscillation. The tropical 30 to 60-day oscillation has the characteristics of the Kelvin-Rossby wave. The impact of satellite-derived precipitation （and its associated latent heating） on the ISO intensity is limited in the GEOS-3 assimilation system. However, its impact on the ISO spatial structures is obvious. Overall, the results demonstrate a better eastward propagation and a northward propagation of ISO with the TRMM precipitation simulation, indicating that latent heating is very important in exciting the equatorial ISO. Key words： 20 to 30-day oscillation; 30 to 60-day oscillation; GEOS data assimilation system; Kelvin wave; TRMM precipitation
基金supported by the National Natural Science Foundation of China(Grant Nos.41575029 and 41375106)the Six Talent Peaks project of Jiangsu Province(Grant No.2014JY021)
文摘Direct assimilation of cloud-affected microwave brightness temperatures from AMSU-A into the GSI three-dimensional variational （3D-Var） assimilation system is preliminarily studied in this paper. A combination of cloud microphysics param- eters retrieved by the 1D-Var algorithm （including vertical profiles of cloud liquid water content, ice water content, and rain water content） and atmospheric state parameters from objective analysis fields of an NWP model are used as background fields. Three cloud microphysics parameters （cloud liquid water content, ice water content, and rain water content） are ap- plied to the control variable. Typhoon Halong （2014） is selected as an example. The results show that direct assimilation of cloud-affected AMSU-A observations can effectively adjust the structure of large-scale temperature, humidity and wind anal- ysis fields due to the assimilation of more AMSU-A observations in typhoon cloudy areas, especially typhoon spiral cloud belts. These adjustments, with temperatures increasing and humidities decreasing in the movement direction of the typhoon, bring the forecasted typhoon moving direction closer to its real path. The assimilation of cloud-affected satellite microwave brightness temperatures can provide better analysis fields that are more similar to the actual situation. Furthermore, typhoon prediction accuracy is improved using these assimilation analysis fields as the initial forecast fields in NWP models.
