ATMS卫星资料偏差订正方法研究

ATMS是继AMSUA/MHS之后新一代微波垂直探测仪,其空间分辨率和湿度探测通道数均有较大提升。对于新一代垂直探测仪资料同化应用,资料偏差订正尤为关键。研究了NPP卫星搭载的新一代微波探测仪(ATMS)资料偏差订正问题。根据ATMS资料特点,以欧洲中期天气预报中心(ECMWF)原全球TIROS大气垂直探测仪(TOVS)资料离线偏差订正经验方法为基础,在WRFDA框架下,对数值预报起主要作用的10个ATMS通道亮温进行偏差订正。统计结果表明:1扫描偏差具有纬度依赖性,各通道不同纬度带和各扫描位置表现出不同特征;2通过对比偏差订正前后观测残差概率密度分布特征,获得订正结果是合理的。偏差订正后的ATMS观测残差概率分布更接近于均值为0的高斯分布;3经过偏差订正后,大多通道观测残差标准差有所降低,个别湿度通道减小幅度不大,特别是19通道还有增大的现象。

A RADIANCE-BIAS CORRECTION SCHEME OF Advanced Technology Microwave Sounder (ATMS) FOR RADIANCE ASSIMILATION

ATMS(Advanced Technology Microwave Sounder) is another new generation Microwave Sounder after AMSUA/MHS, which has high spatial resolution and humidity detecting channels increase greatly. For the new generation of vertical sounder data assimilation applications, radiance bias correction is particularly critical. This research focuses on the bias correction of ATMS data a new generation microwave sounder equipped on NPP satellite. According to the characteristics of ATMS data, a new bias correction scheme for ATMS radiance data is developed referencing the classical off-line scheme which had been used in European Centre for Medium-Range Weather Forecasts (ECMWF), In the framework of WRFDA, brightness temperature deviation of 10 ATMS channel were revised which play a major role in the numerical prediction. Statistical results shows that:(1) The scan bias has latitude-dependent, which shows the difference in different latitudes and scanning angle of each channel.(2) The revised result is reasonable by comparing the probability density distribution of observed residuals before and after the bias correction. The observation residuals of ATMS data after the whole bias correction procedure fit a normal distribution (mean =0).(3) After the bias correction, standard deviation of observation residuals decreased in most channels, individual humidity channel decreases marginally, and there is a increasing phenomenon in channel 19 particularly.