对称模式下的CHAMP弯曲角掩星数据同化

ASSIMILATION OF BENDING ANGLE FROM GPS RADIO OCCULTATION IN SYMMETRICAL MODEL

简单介绍了无线电掩星技术探测行星大气的发展史,列举了该技术中存在的若干问题。从 Eyre提出的统计学的最优估计反演方法,比较了用相位、弯曲角和折射率作为同化因子时出现的问题和各自的优缺点。对弯曲角同化因子,以欧洲中期天气预报中心(ECMWF)资料为背景场,运用一维变分技术,进行CHAMP掩星观测资料变分同化反演,从而获得水汽和温度剖面。将反演获得的气象剖面与非同化的剖面作比较,并且采用相应的探空气球资料作为验证,可以看出变分同化技术比传统的标准反演技术反演误差小。证实掩星数据资料的一维变分同化技术可以改进目前的数值天气预报模式。

The Global Positioning System/Low Earth Orbit （GPS/LEO） radio occultation technique gives a new method to probe earth＇ s atmosphere. This method gives the vertical profiles of pressure, water vapor and temperature retrieved from GPS/LEO occultation data, which are potentially valuable data source for the meteorological community and atmospheric science. The assimilation process of GPS/ LEO occultation data may effectively improve the quality of retrieved meteorological profiles, and further the quality of the current numerical weather prediction （NWP） model. Through one dimensional variational （1 DVAR） retrieval technique, the refractivity or the bending angle profiles from GPS!LEO occultation can possibly selected to be assimilated into NWP model, and then the atmospheric temperature and water vapor profiles, as well as the surface pressures are retrieved. In this paper, we present the 1 DVAR retrieval technique of bending angle in symmetrical model, and calculate some profile samples from CHAMP occultation bending angle observations based on Levenberg-Marquardt algorithm associated with the background field from the European Center for Medium Range Weather Forecasting （ECMWF） analyses. As a part of discussion, the retrieved profiles are