中国区域高空三种气温、湿度资料交叉对比

Cross Comparison of Three Kinds of Upper Air Temperature and Humidity Data over China

本文对比分析了2011—2013年中国区域L波段探空气温、湿度廓线,COSMIC掩星气温、湿度廓线和ERA-Interim再分析资料的气温、湿度廓线之间的差异。对比显示,从时间变化来看,三者之间有很好的正线性相关关系。除10 hPa以上的少数层次外,三种气温资料之间互相吻合较好,彼此偏差范围在±0.4℃之间,偏差标准差在1~2℃,对流层中高层,L波段探空气温受太阳辐射影响较大,气温偏高,与COSMIC相比,L波段探空偏高最高可达到0.64℃。而对于相对湿度,三种数据存在明显差异。对流层中低层到对流层顶L波段探空存在不同程度的偏干,且有较明显的昼夜、季节和区域差异：白天、春夏季和南方潮湿气候区域偏干更明显。一般来说,在对流层顶附近区域,L波段探空相对湿度偏干较明显,200 hPa附近及以上L波段探空相对湿度转为偏湿。在对流层顶以下,L波段探空与COSMIC掩星、ERA-Interim再分析相对湿度具有明显的正相关,对流层顶以上表现为负相关。

In this study,the differences of temperature and humidity profiles over China obtained from L band sounding system,COSMIC occulation observation system and ERA-Interim reanalysis data during the period 2011 — 2013 are compared.Time series comparisons show a good positive linear correlation among these three data sets.In addition to a few levels above 10 hPa,L band,COSMIC occultation and ERA-Interim reanalysis temperature data accord well with each other,with the temperature bias ranging within ＋0.4℃,and the standard deviation between 1℃ and 2℃.L band temperature is higher due to the great influence by solar radiation in the middle to upper troposphere,with the maximum bias of 0.64℃when compared with COSMIC occultation.As for relative humidity,things are strikingly different.L band relative humidity data exhibit a varying degree of dry bias between the lower troposphere and the upper troposphere.Moreover,there are obvious diurnal,seasonal and climate regional differences,and the differences become even more evident during daytime,spring/summer period,and over south moisture climate areas.Generally,the dry bias is more obvious in the region near the top of troposphere;L band relative humidity turns to wet bias at above 200 hPa atmospheric pressure layer.L band and COSMIC occultation sounding relative humidity,ERA-Interim relative humidity have positive correlations obviously below the top of troposphere.Nevertheless,there is a negative correlation above the tropopause.