Ascending–Descending Bias Correction of Microwave Radiation Imager on Board FengYun-3C
Ascending–Descending Bias Correction of Microwave Radiation Imager on Board FengYun-3C
复制标题
风云三号C星微波辐射成像仪升序-降序偏差校正
DOI：
10.1109/tgrs.2018.2881094
复制
发表时间：
2019-06
影响因子：
8.2
通讯作者：
Songyan Gu
中科院分区：
文献类型：
--
作者：
Xinxin Xie;Shengli Wu;Hongxin Xu;Weimin Yu;Jiakai He;Songyan Gu
微波辐射成像仪（MWRI）是风云三号C气象卫星上最重要的微波有效载荷之一。仪器存在校准异常，并且在所有通道的上升通道和下降通道之间显示出观察-背景（O-B）校准偏差差异（以下称为AD偏差）。MWRI在上升轨道和下降轨道之间的校准偏差差异阻碍了数值天气预报和再分析系统的资料同化。本文在简要介绍MWRI仪器校准过程的基础上，提出了一种基于物理的MWRI校准校正算法。建立了所观察到的亮度温度与热负载反射器的物理温度之间的关系，以减轻在先前的校准过程中没有准确估计的所有通道处的发射热反射器的侵入。使用一年观察值进行校正前后比较表明，AD偏倚有效降低，即，在校正公式中对热反射体的发射率进行校正时，MWRI辐射亮度的平均值由校正前的~ 2K减小到校正后的<0.2K，而MWRI辐射亮度的平均值变化可以忽略不计。
Microwave radiation imager (MWRI) is regarded as one of the most important microwave payloads on board China FengYun-3C Meteorological Satellite. The instrument suffers from calibration anomalies and exhibits observation- background (O-B) calibration bias difference between the ascending and descending passes at all channels (hereinafter AD bias). The calibration bias difference of MWRI between ascending and descending orbits hampers data assimilation in the numerical weather predictions and reanalysis systems. This paper proposes a physical-based correction algorithm for MWRI calibration, following a brief introduction to the calibration process of the instrument. The relationship between the observed brightness temperatures and the physical temperature of the hot load reflector is established to mitigate the intrusion of the emissive hot reflector at all channels which was not accurately estimated in the previous calibration process. Before- and after-correction comparisons using one-year observations show that the AD bias is effectively reduced, i.e., from ~2 K before correction to less than 0.2 K after correction, when rectifying the emissivity of the hot reflector in the calibration equation, whereas the change in the mean values of MWRI radiance is negligible.