Review of Geostationary Interferometric Infrared Sounder
The interferometer of geostationary interferometric infrared sounder.
As a main instrument onboard geostationary meteorological satellite FY-4, geostationary interferometric infrared sounder (GIIRS) is used to measure the infrared spectrum of the earth atmosphere. The spectrum is inverted by meteorologists to obtain three-dimensional distribution of humidity and temperature in the atmosphere and its variation with time.
Traditional sounders, such as sounder of geostationary operational environmental satellite (GOES) in orbit and infrared atmospheric sounder of China's FY-3, detect the spectrum based on the on principle of optical filter. GIIRS is designed based on the principle of Fourier-transform spectroscopy. Its core component is interferometer and its spectral channels are more than 1600. And GIIRS has an optical imaging system which conjugates targets with sensing elements (SE). Using a N×M-dimensional SE to obtain interferogram signals, GIIRS can realize large area coverage dynamic sounding in short time which is very important for weather prediction.
The primary user of GIIRS is China Meteorological Administration. By GIIRS, observation of air vertical flow is realized for the first time internationally. In addition, because GIIRS is a hyperspectral infrared sounder in reality with a spectral resolution of 0.625 cm-1, the field of application can also cover environmental monitoring, danger forecast and military etc.
The history of atmospheric sounding with the Fourier transform spectroscopy (FTS) instruments for space began in 1969 with the launch of the Nimbus meteorological satellite which carried the NASA interface region imaging spectrograph (IRIS) instrument. In 2000, geostationary imaging Fourier transform spectrometer (GIFTS) started the pre-research of the technologies of interferometric infrared sounder, but for some reasons, its technique is not adopted by GOES-R. MTG-IRS is being developed with similar technologies and is expected to launch in 2023. This work has been published in Chinese Optics Letters, Volume 16, Issue 11, 2018 (Jianwen Hua et al.. Review of Geostationary Interferometric Infrared Sounder)
For the successful launch of geostationary interferometric infrared sounder, in November 2017, at the International Strategic Committee Meeting on Chinese Meteorological Satellite Programs held by WMO, WMO expert, conference chair, Dr. Tillmann Mohr pointed out: GIIRS, boarded on FY-4 satellite, make China be in the lead of atmospheric sounding on geostationary orbit in the world.
From pre-research to the end of on-orbit test, the development process of GIIRS boarded on FY-4 satellite took 16 years. In the future, it will be loading the sequent satellites. The development of weather observation needs higher spatial resolution and time resolution, so the further research will focus on the key technologies of infrared SE arrays with large size.
风云四号干涉式大气垂直探测仪的研究进展
风云四号大气垂直探测仪干涉仪
干涉式大气垂直探测仪（GIIRS）是地球静止轨道气象卫星风云四号的主要仪器。它用来测量大气的红外辐射光谱。此光谱经过气象学专家的反演，可获得大气中湿度、温度的三维分布和随时间的变化。
传统的探测仪如目前还在天上运行的美国GOES探测仪、中国的风云三号红外分光计多是按滤光片分光原理探测光谱的。它们的光谱通道仅有二十几个，探测器只有十几个。GIIRS是按傅里叶变换光谱仪设计的，核心部件是干涉仪，光谱通道数有1600多个。GIIRS具有光学成像系统，使得目标与传感元件（SE）共轭，用于接收干涉信号，实现了大范围动态探测，这对天气预报显得尤为重要。
GIIRS的主要用户为中国气象局。由于它的成功研制和使用，在国际上首次清楚地观测到了气流的上下运动。由于GIIRS本质上是一台光谱分辨率为0.625 cm-1的高光谱分辨率红外探测仪，它在环境、险情预报和军事等方面也有重要的应用。
空间傅里叶变换光谱仪（FTS）的大气探测历史始于1969年，Nimbus气象卫星携带红外干涉分光计（IRIS）发射成功。 2000年，地球同步轨道傅里叶变换成像光谱仪（GIFTS）项目开始对干涉红外测深仪技术进行预研究，但由于某些原因，R系列地球同步轨道环境卫星（GOES-R）没有采用其技术。欧洲第三代气象卫星的红外探测仪（MTG-IRS）正在开发类似技术，预计将于2023年发射。相关研究结果发表于Chinese Optics Letters 2018年第16卷第11期（Jianwen Hua et al.. Review of Geostationary Interferometric Infrared Sounder）。
对于风云四号大气垂直探测仪的成功发射，在2017年11月召开的WMO风云系列卫星发展战略咨询会上，WMO专家、会议主席莫尔博士指出：中国在静止轨道上的探测在世界上处于领先地位。
风云四号A星GIIRS从概念研究到在轨测试成功，历时16年。今后它还将装载于风云后续星。气象观测的进一步需求是提高时间分辨率和空间分辨率，对应的主要关键技术进步是研制更大规模的红外探测器。