CAJ | 학술논문

COSMIC是一个由6颗低轨卫星组成的用于天气、气候和电离层观测的空基GPS星座观测系统,从2006年9月开始每天可提供覆盖全球的约2000～3000个掩星点,掩星过程可提供从40 km高空到近地面的大气温、压、湿的廓线资料.为了有效利用这些资料,以探宅资料为基准,对2007年1-10月我国及邻近区域的COSMIC掩星资料进行精度、可用性和全天候件的检验.结果表明:COSMIC反演的温度和折射率的精度很高,水汽压的精度相对较差.与NCEP/NCAR再分析资料相比,折射率和湿度廓线有更高精度.
COSMIC시일개유6과저궤위성조성적용우천기、기후화전리층관측적공기GPS성좌관측계통,종2006년9월개시매천가제공복개전구적약2000～3000개엄성점,엄성과정가제공종40 km고공도근지면적대기온、압、습적곽선자료.위료유효이용저사자료,이탐택자료위기준,대2007년1-10월아국급린근구역적COSMIC엄성자료진행정도、가용성화전천후건적검험.결과표명:COSMIC반연적온도화절사솔적정도흔고,수기압적정도상대교차.여NCEP/NCAR재분석자료상비,절사솔화습도곽선유경고정도.
The COSMIC (Constellation Observing System for Meteorology Ionosphere and Climate) consists of six Low Earth Orbit (LEO) satellites. Based on the GPS signals observed by LEO in the occultation condition of the GPS satellites, the profiles of atmospheric temperature, pressure, humidity and ionosphere are retrieved. COSMIC provides these to about 2000 to 3000 GPS soundings globally every day since September 2006, and it can be the effective supplementary of regular radiosonde. COSMIC data is collected in the area of China and Northwest Pacific during the period of January to October in 2007. And the precision, applicability and characteristics of fitting all weather condition are evaluated by the error statistics based on radiosonde data.The results show that the accuracy of temperature profiles retrieved from COSMIC is excellent. The root-mean-square error (RMS) is less than 2 K and the relative error is less than 1%. The retrieved refrac-tivity above 500 hPa level is very accurate, with the RMS less than 1, while under 500 hPa level the RMS increases from 1 to 10 near the ground. The precision of water vapor is high above 500 hPa level, but the RMS increases linearly from 0. 2 hPa or less to 2 hPa near the ground under 500 hPa level. Meanwhile the error comparison between COSMIC data and NCEP (National Center of Environment Precipitation) reanal-ysis data shows that COSMIC data have higher accuracy than NCEP in vapor pressure and refractivity, for instance, the relative error of vapor pressure of COSMIC is 2%-5% less than NCEP data. Additionally two COSMIC occultation events in the clouds are studied to compare COSMIC data with the nearby radiosonde and airborne dropsonde observations. It's validated that the profiles of the temperature, vapor pressure and refractivity of COSMIC data coincide well with the corresponding radiosonde profiles, so the COSMIC data are appropriate under all weather condition.