三年地基微波辐射计观测温度廓线的精度分析

The temperature profile comparison between the ground based microwave radiometer and the other instrument for the recent three years

中文关键词:  地基微波辐射计， 温度廓线， 标定， 反演， 精度

英文关键词:Ground based microwave radiometer, Temperature profile, Calibration, Retrieval, Precision

中文摘要:

      对安装在北京南郊观象台的地基微波辐射计测量的温度廓线数据的精度进行了分析。首先在2006年9月晴天条件下，对比由7个氧气通道测量的亮温与由微波辐射传输模式计算的亮温。得到51.250 GHz的测量值与计算值的标准差值最大，为3.8 K，其余通道均小于1.8 K。2种亮温的偏差值以及绝对偏差值，在51.250和52.280 GHz处大于1.0 K，在其余5个通道处都小于1.0 K。2种亮温拟合直线的斜率，在52.280和53.850 GHz处分别为0.66与0.7，其余通道都大于0.8。然后，使用2005年9月—2008年8月的观测数据，对比地基微波辐射计与探空同时观测的大气温度。结果显示，2种测量技术的差异随高度而增大。另外，将3a观测数据按照季节以及晴天与非晴无降水天进行对比分析。结果显示，不同季节２种测量技术存在不同差异。其中，夏季测量差异最小。而晴天测量差异在3.250 km以下比非晴无降水天小。

英文摘要:

      The brightness temperatures between the measurement by the ground-based 12-channel microwave radiometer and that computed by the radiative transfer theory are compared. The data are measured in sunny day in September 2006. The results are as follows. The standard deviation of Tb in 51.250 GHz is 3.8 K, which is the maximum. The values from other channels are all less than the value in the 51.250 GHz. The bias values of Tb in 51.250 GHz and 52.280 GHz are larger than 1.0 K. The bias values in the other channels are less than 1.0 K. The slopes of the Tb fitting line are 0.66 and 0.7 in 52.280 GHz and 53.850 GHz, respectively. The slopes of other channels are larger than 0.8.  The temperature profile measured by the ground based 12-channel microwave radiometer are compared with that measured by the Radiosonde from September 2005 to August 2008 in Bejing. The difference is increasing with the height. The measurements are analysed in terms of four seasons. From 0 to 10 km (with the heights from 8 km to 9 km excluded), the difference in Summer is larger than any of those in all other seasons. From 0 to 2.750 km, the difference in Spring is larger than in all other seasons. From 2.750 km to 3 km, the difference in Winter is larger than in all other seasons. From 3 km to 9 km, the difference in Autumn is larger than in all other seasons. There exists clear difference between the temperature profile measurements in sunny day and in cloudy day. The slope in sunny day is larger than that in cloudy day, which may be due to the sample number for the comparison.