风云三号B星红外分光计的定标和验证
Calibration and Validation of the InfraRed Atmospheric Sounder Onboard the FY3B Satellite
中文摘要：
搭载于风云三号A星和B星上的红外分光计（IRAS）分别于2008年5月27日和2010年11月5日成功发射。该仪器主要提供从可见光到红外波长范围内多通道的辐射观测，并可应用于资料同化、全球大气温度和水汽廓线反演等领域。搭载于风云三号A星上的IRAS由于滤光轮转速不稳定，导致仪器观测不连续。风云三号B星上的IRAS运行正常，处于稳定的业务模式。利用仪器在轨3个月期间的资料，进行了一系列的在轨定标和验证试验，对IRAS仪器的性能进行了一系列的验证，包括冷空和暖黑体定标计数值的长期趋势、噪音等效辐射率等。利用IRAS和红外大气探测干涉仪（IASI）同时观察到的地球场景进行比较，证明了两种观测非常相似。另外，将FY3B/IRAS红外通道的观测与NOAA-19/HIRS对应的通道的辐射传输模式模拟进行了对比。对比结果显示相对于HIRS，部分IRAS红外通道，尤其是通道1到10，15，19和20偏差很小。但是少数通道，如通道13，16和18有较大的偏差。造成这些偏差的原因仍需要进一步的研究。
中文关键词：
定标验证，风云3号，红外分光计（IRAS），在轨定标
KeyWords：
Calibration validation, FengYun 3, InfraRed Atmospheric Sounder (IRAS), on-orbit calibration
Abstract：
InfraRed Atmospheric Sounder (IRAS) instruments were successfully launched onboard the FengYun-3A (FY3A) and FengYun-3B (FY3B) satellites on May 27, 2008, and November 5, 2010, respectively. They aim at providing multichannel radiances within the spectral range of visible to infrared (IR) wavelengths for many environmental applications, including data assimilation and retrievals of global atmospheric temperature and humidity profiles. However, the velocity of the filter wheel of the first IRAS onboard FY3A is unstable and, therefore, induced a discontinuity in the measurement. The IRAS onboard FY3B works well in normal and stable operational mode since its launch without any anomaly. A variety of postlaunch calibration/validation tasks are conducted using onorbit data during a period of three months. This paper presents on-orbit verification of IRAS instrument performance, including longterm trends of the space and warm calibration counts and noise equivalent delta radiance. The Earth scenes observed simultaneously by IRAS and Meteorological Operational Satellite Programme (METOP)/Infrared Atmospheric Sounding Interferometer were obtained and compared to demonstrate a close similarity between the two measurements. Furthermore, the IR channel observations from FY3B/IRAS are compared with those from National Oceanic and Atmospheric Administration-19/ High Resolution Infrared Radiation Sounder (HIRS) equivalent channels and simulations from a radiative transfer model. The results show that some of IRAS IR channels perform very well, particularly for channels 1–10, 15, 19, and 20, compared to those of HIRS. Several channels, such as 13, 16, and 18, however, display some large biases. The causes of these increased biases are still under investigation.