利用2007 -2009年CloudSat卫星云廓线雷达（nadir-pointing cloud profiling radar， CPR）资料， 气象、 电离层和气候卫星联合观测系统（Global Constellation Observing System for Meteorology， Ionosphere， and Climate， COSMIC）掩星资料， 分析了不同类型云内COSMIC掩星资料与欧洲中期天气预报中心（European Centre for Medium-Range Weather Forecasts， ECMWF）和美国国家环境预报中心（National Centers for Environmental Prediction， NCEP）分析场之间的折射率偏差特征。COSMIC与ECMWF和NCEP之间的折射率偏差分别用 N b i a s^{\mathrm{E}\mathrm{C}\mathrm{M}\mathrm{W}\mathrm{F}}和 N b i a s^{\mathrm{N}\mathrm{C}\mathrm{E}\mathrm{P}}表示。研究发现， N b i a s^{\mathrm{E}\mathrm{C}\mathrm{M}\mathrm{W}\mathrm{F}}在积云、 层积云、 高积云和高层云中的最大值分别为1.2%、 0.2%、 0.5%和0.2%， 而 N b i a s^{\mathrm{N}\mathrm{C}\mathrm{E}\mathrm{P}}则分别为1.8%、 0.5%、 0.5%和0.4%。在层积云的对流层下层 N b i a s^{\mathrm{N}\mathrm{C}\mathrm{E}\mathrm{P}}存在较大的负值， 而 N b i a s^{\mathrm{E}\mathrm{C}\mathrm{M}\mathrm{W}\mathrm{F}}为正值。折射率的正偏差随着液态水含量增加而增加。从全球分布来看， 赤道辐合带云量丰富， N b i a s^{\mathrm{N}\mathrm{C}\mathrm{E}\mathrm{P}}和 N b i a s^{\mathrm{E}\mathrm{C}\mathrm{M}\mathrm{W}\mathrm{F}}也存在明显的正偏差， 它在空间上和水汽的正偏差以及温度的负偏差高度相关。

The Global Constellation Observing System for Meteorology， Ionosphere， and Climate （COSMIC） radio occultation （RO） from 2007 to 2009 were collocated with the CloudSat nadir-pointing cloud profiling radar （CPR） in time and space in this study.We investigated the characteristics of fractional refractivity differences between COSMIC RO and the analysis of the European Centre for Medium-Range Weather Forecasts （ECMWF） and the National Centers for Environmental Prediction （NCEP） within the different clouds. N b i a s^{ECMWF} and N b i a s^{NCEP}indicate the fractional differences of refractivity between COSMIC RO and ECMWF， and COSMIC RO and NCEP analysis， respectively.The maximum values of N b i a s^{ECMWF} within cumulus， stratocumulus， altocumulus and altostratus are 1.2%， 0.2%， 0.5%， and 0.2%.The highest values of N b i a s^{NCEP}are 1.8%， 0.5%， 0.5% and 0.4%， respectively.In the lower troposphere， the value of N b i a s^{ECMWF} is positive and increases with the liquid water content， whereas the value of N b i a s^{NCEP} is negative.From the perspective of global distribution， large positive refractivity differences for both ECMWF and NCEP analyses are shown in the equatorial convergence zone， which is highly correlated with the positive bias of water vapor and the negative bias of temperature in space.