风云三号卫星微波温度计的在轨性能长期稳定性分析
Long-Term Calibration and Accuracy Assessment of the FengYun-3 Microwave Temperature Sounder Radiance Measurements
中文摘要：
中国风云三号（FY-3）A星于2008年5月27日成功发射，其上装载的微波温度计（Microwave TemperatureSounder，MWTS）有4个通道，频率分别为50.3，53.596，54.94和57.29GHz，可提供地面至平流层下部的大气温度廓线信息。介绍了MWTS的仪器特征和定标方法，对FY-3A发射后MWTS的仪器性能相关参数的长序列特征进行了监测分析，这些参数主要包括灵敏度、冷空和内部暖黑体的计数值、仪器温度和通道增益。通过再分析资料和微波辐射传输模拟，比较了FY-3A卫星MWTS与NOAA-18卫星先进微波温度探测器（Advanced Microwave Sounder Unit-A,AMSU-A）的观测和模拟的亮温偏差。结果表明，MWTS所有通道的灵敏度值优于其指标；通道1和3的亮温偏差与AMSU-A接近；通道2和4的偏差比AMSU-A要大一些。
中文关键词：
定标，风云三号（FY-3），微波温度计（MWTS）
KeyWords：
Calibration, FengYun-3 (FY-3), Microwave Temperature Sounder (MWTS)
Abstract：
The Chinese FengYun-3 (FY-3)A satellite was successfully launched on May 27, 2008, with a Microwave Temperature Sounder (MWTS) onboard. MWTS has four channels with frequencies of 50.3, 53.596, 54.94, and 57.29 GHz, respectively. The MWTS measurements are primarily used for profiling atmospheric temperatures from surface to lower stratosphere. MWTS is a cross-track scanning instrument, and its Earth-view measurements are calibrated through the warm target and cold space measurements during every scan cycle. In this paper, the FY-3A MWTS and its channel characteristics are first introduced. The calibration process and the postlaunch instrument performance are then presented, including the long-term trends of noise equivalent differential temperature (NEDT), calibration counts from cold space and warm targets, instrument telemetry, and channel gains. The observed and simulated brightness temperature (BT) differences of MWTS and Advanced Microwave Sounding Unit-A (AMSU-A) are compared. It is shown that the MWTS NEDT values at all channels are much better than its specification. The BT biases of MWTS channels 1 and 3 with respect to the simulations are similar in magnitude to those from National Oceanic and Atmospheric Administration-18 AMSU-A. The MWTS biases at channels 2 and 4 are larger than AMSU-A.