基于几何光学反演方法,由附加相位延迟序列出发,对2007年6月6日发生在澳大利亚上空的一次COSMIC掩星事件进行了反演。将反演得到的折射角、折射率、干温与湿度廓线分别与COSMIC数据分析与管理中心(COSMIC data analysis and archive center,CDAAC)的相应产品进行了比较。结果表明,两者在低对流层存在较显著的差异。以距离该掩星地点300 km以内、观测时间差异2 h以内的无线电探空资料为参照,反演的折射率廓线与CDAAC的折射率廓线在低对流层都存在一定的误差。对于该掩星事件,CDAAC通过变分法反演的湿度廓线并不比本文的反演结果更接近探空廓线;在1 km以下,其变化趋势甚至与探空结果相矛盾。
In recent years, radio occultation （RO） technology making use of global positioning system （GPS） signals has been exploited to obtain profiles of atmospheric parameters in the neutral atmosphere. In this paper, the RO refractivity profiles obtained from the Constellation Observing System for Meteorology, Ionosphere and Climate （COSMIC） mission are statistically compared with the observations of 38 radiosonde stations provided by the Australian Bureau of Meteorology during the period from 15 July 2006 through 15 July 2007. Different collocation criteria are compared at first, and COSMIC RO soundings that occur within 3 hours and 300 km of radiosonde measurements are used for the final statistical comparison. The overall results show that the agreements between the COSMIC refractivity profiles and the radiosonde soundings from the 38 stations are very good at 0-30 km altitude, with mean absolute relative refractivity deviations of less than 0.5%. Latitudinal comparisons indicate that there are negative refractivity deviations in the lower troposphere over the low latitude and middle latitude regions and large standard deviations exist in the lower troposphere of low latitude regions, which can reach up to ～6%. The comparisons of COSMIC RO refractivity profiles and radiosonde observations for 3 polar stations in four different seasons indicate that the accuracy of GPS RO profiles is better in the Austral summer and autumn than in the Austral spring and winter during the year from September 2006 to August 2007.
以全球无线电探空数据和美国环境预报中心（National Centers for Environmental Prediction，NCEP）预报模式为参照，对COSMIC数据分析与管理中心（COSMIC Data Analysis and Archive Center，CDAAc）提供的2007—06-01～2007—06—30的气象、电离层与气候星座观测系统（the constellation observing system for meteorology，Ionosphere，and climate，COSMIC）的GPS掩星折射指数廓线进行了统计验证。结果表明，掩星廓线的精度在高纬度地区最好，在低纬度地区最差。中、低纬度带掩星廓线相对于探空廓线有系统性相对偏差，该偏差在掩星廓线与NCEP预报廓线的比较中不存在，说明探空数据的质量是造成这种偏差的主要原因，这可能与不同地区所采用的无线电探空仪的性能有关。
