在NCEPGDAS中同化MSG和GOES资料

Assimilation of MSG and GOES data in the NCEP GDAS

首次将MSG-2(Meteosat Second Generation-2)卫星上的旋转增强可见光及红外成像仪(Spinning Enhanced Visible and Infrared Imager,SEVIRI)的观测资料同化到美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)全球资料同化系统(global data assimilation system,GDAS)中。对当前的地球静止业务环境卫星(Geostationary Operational Environmental Satellite,GOES)成像仪资料的同化问题也进行了进一步探讨。利用CRTM(The Community Radiative Transfer Model)模式,对SEVIRI辐射率观测资料进行了模拟。为了对红外辐射率资料进行模拟,CRTM模式中的几个关键部分得到改进,例如:动态更新地面发射率资料以及采用了快速精确的气体吸收模块。为了改进对SEVIRI和GOES成像仪辐射率资料的模拟效果,采用了GSICS(The Global Space-Based Inter-Calibration System)标定订正。初步研究结果表明,包含对SEVIRI辐射率资料的水汽通道(6.25和7.35μm)和二氧化碳通道(13.40μm)的同化对GFS(Global Forecast System)6d预报具有显著的正影响;而对其他5个SEVIRI红外窗口通道资料的同化则减小了这种正影响。通过应用GSICS标定算法,订正了SEVIRI和GOES-12成像仪观测资料的偏差,提高了对GFS预报的影响。此外,还需作进一步研究来提高对SEVIRI红外窗口通道辐射率资料同化的有效性。

Infrared（IR） observations from Spinning Enhanced Visible and Infrared Imager（SEVIRI） on board Meteosat Second Generation（MSG）-2 satellite are assimilated into NCEP （National Centers for Environmental Prediction） global data assimilation system（ GDAS ）. The assimilation of current Geosta- tionary Operational Environmental Satellite（GOES） Imager data was also reinvestigated. The Commu- nity Radiative Transfer Model（CRTM） was used as observation operator for the simulation of SEVIRI radiance observations. The CRTM was enhanced with several critical components for IR radiance simu- lation, such as a dynamically-updated land surface emissivity data, as well as fast and accurate gaseous absorption modules. The Global Space-Based Inter-Calibration System （ GSICS ） calibration corrections were applied to improve the simulation of SEVIRI and GOES Imager radiances. Preliminary results show that inclusions of the SEVIRI radiances at water CO2channel（ 13.40 μm） in Global Forecast System（GFS） vapor channels （ 6. 25 and 7.35 μm ） and produced significant positive impacts on the six-day forecasts. Assimilation of other five SEVIRI IR window channels in GFS reduces the positive impact. By applying GSICS calibration algorithm to correct SEVIRI and GOES-12 Imager observations biases, the impacts on GFS forecast were improved. Further studies are being carried out to improve the effective assimilation of SEVIRI IR window channels radiances.