| 风云三号A星微波湿度计主探测通道辐射特性 |
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| 引用本文： | 谷松岩,王振占,李靖,张升伟.风云三号A星微波湿度计主探测通道辐射特性[J].应用气象学报,2010,21(3):335-342. |
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| 作者姓名： | 谷松岩 王振占 李靖 张升伟 |
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| 作者单位： | 1.中国气象局中国遥感卫星辐射测量和定标重点开放实验室国家卫星气象中心, 北京 100081 |
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| 摘 要： | 微波湿度计装载在2008年5月27日发射升空的我国新一代极轨气象卫星风云三号A星上,完成全天候大气湿度信息的被动微波遥感探测。主探测通道中心频点位于183.31 GHz,设置有3个双边带探测通道。为保证风云三号微波湿度计在轨定量应用,研制过程中完成了地面真空试验。该文对风云三号A星微波湿度计正样产品真空试验数据进行了定量分析,数据分析结果表明:风云三号A星微波湿度计正样产品主探测频点183.31 GHz附近的3个探测通道等效噪声温差小于等于0.91 K;定标准确度优于1.05 K;真空试验过程中微波湿度计辐射定标结果稳定。风云三号A星微波湿度计发射前辐射定标特性分析结果,为仪器在轨定量应用奠定了基础。
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| 关 键 词： | 风云三号 微波湿度计 辐射特性 |
| 收稿时间： | 2009-04-13 |
| 修稿时间： | 1/6/2010 12:00:00 AM |
The Radiometric Characteristics of Sounding Channels for FY-3A/MWHS |
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| Gu Songyan,Wang Zhenzhan,Li Jing,Zhang Shengwei.The Radiometric Characteristics of Sounding Channels for FY-3A/MWHS[J].Quarterly Journal of Applied Meteorology,2010,21(3):335-342. |
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| Authors: | Gu Songyan Wang Zhenzhan Li Jing Zhang Shengwei |
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| Affiliation: | 1.Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites, National Satellite Meteorological Center, China Meteorological Administration, Beijing 1000812.Center for Space Science and Applied Research Chinese Academy of Sciences, Beijing 100190 |
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| Abstract: | The microwave humidity sounder (MWHS) is installed on new generation of Fengyun polar orbiters, FY 3A satellite, which is launched on 27 May 2008, for global all weather humidity sounding. The sounder produced by Center for Space Science and Applied Research Chinese Academy of Sciences has 5 channels in the range of 150—191 GHz. Around the center frequency of 183.31 GHz water vapor line, there are 3 sounding channels at 183.31±1, 183.31±3, and 183.31±7 GHz. All these three channels have two pass bands, and are only sensitive to vertical polarization at nadir. At 150 GHz there are 2 subsidiary window channels of V/H polarization.Every 2.667 s, MWHS scans through 98 earth views, 3 space views, and 3 internal black body target views. Each pixel has a nominal field of 1.1° (15 km on surface at nadir). One scan line could cover±53.35° from sub satellite point. The instruments are comprehensively tested to determine their actual antenna, spectral, thermal and radiometric characteristics.In order to determine the radiometric performance and verify the method for calibration of MWHS, an extensive test is performed on the flight models. The instruments are placed in a 3 m thermal-vacuum chamber where the temperature could be controlled simulating the conditions in orbit and they are used to observe an earth target and a space one. The thermal-vacuum facility is used to modify temperature circularly to test the instrument in vacuum before launch. The temperature of MWHS is controlled at 273 K, 283 K, 293 K and 303 K except in the earth and space directions where the shroud is maintained at any desired temperature between 100 K and 350 K for an earth target, and 90 K for space target. The whole targets temperature is measured to an absolute accuracy of better than 0.1 K by regularly calibrating the PRT with a standard one traceable to a national standard.The T/V test data are quantitatively analyzed, and the TNE of MWHS three channels on 183.31 GHz water vapor line at 183.31±1, 183.31±3 and 183.31±7 GHz are calculated. All three channel TNEare less than 0.90 K. MWHS is designed to allow a 2 point calibration, for each scan line, from the internal target and space views. The instrument response is assumed to be linear between these two calibration points. After correcting all the biases, the calibration accuracy is well below 1.05 K, and the changes of calibration results with instrument temperature are relatively small. Therefore, it's expected that temperature variations in orbit will not affect measuring brightness temperatures much.The radiometric characteristics analysis of sounding channels for FY-3A/MWHS will be the base for quantitative application in orbit. And the T/V test results will be directly used in orbit calibrating. Once MWHS is in orbit, the TNE will not be measured directly but the variance of the internal target will provide a measurement of the noise for each channel, and the in orbit radiometric sensitivities can be monitored. The MWHS calibration test can be validated using NWP results and intensive field campaigns. The lab test results will be valuable for interpretation of the in orbit data. |
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| Keywords: | FY-3A MWHS radiometric characteristics |
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