关键词: COSMIC, 无线电掩星观测, 无线电探空, 评估

Abstract: The retrieval product of COSMIC (constellation observing system for meteorology, ionosphere, and climate) radio occultation sounding system was verified using the Chinese radiosonde from 2007 to 2010. The horizontal distance between radiosonde station and the occultation event is within 100 km, and the time window is 1 hour. The comparison is performed from 925 hPa to 10 hPa. Result shows that the temperature of COSMIC agrees well with Chinese radiosonde. The mean temperature bias is ?0.08 K, and the standard deviation is 1.67 K. The water vapor pressure of COSMIC has notable systematic bias from radiosonde on layers above 200 hPa. On layers below 200 hPa, the mean absolute deviation of specific humidity is about +0.080 g/kg, and the standard deviation is about 0.692 g/kg, the mean relative error of water vapor pressure is about +69.6%, and the standard deviation is about 160.0%. The COSMIC quality control process fails to detect some extremely small humidity data which causes large relative error. Here also provides a comparison of 6 radiosonde types with COSMIC product. As result is affected by the background bias from radiosonde which differs on different regions, the COSMIC retrieval product could be used as benchmark if precision requirement is not strictness.

Key words: COSMIC, radio occultation, radiosonde, assessment