以METOP-A、Suomi-NPP历史资料作为参照,系统分析比较了 2008-2020年4颗风云三号卫星的微波温度计(Microwave Temperature Sounder,MWTS)再定标历 史资料质量.结果表明,4颗卫星的MWTS探测性能稳步上升,再定标数据集有效消除了遥感仪器在轨期间数据异常跳变、寿命期内遥感仪器辐射响应衰变、不同卫星间的辐射定标差异等因素影响,大幅提升了 MWTS历史数据集的准确性和均匀性,使得再定标后的对流层和平流层通道数据与国外同类型仪器数据偏差在±0.1 K范围内.本文还重点分析比较了对流层中高层和平流层低层两个探测通道,结果表明FY-3D MWTS再定标数据和美国NOAA卫星应用研究中心STAR长序列数据集针对中高层大气的表现类似,平均亮温在时间变化和空间分布具有相似的特征,月均全球高空亮温年变化趋势差异最大为0.002 4.因此,2020年之后的FY-3D再定标数据,可以接续STAR长序列数据集,用于中高层大气的温度变化检测与分析.
Quality assessment of the long-termrecalibration history dataset of the FY-3 microwave temperature sounder
The Microwave Temperature Sounder(MWTS),an essential sensor onboard China's second-generation polar-orbiting meteorological satellites(FY-3),measures the vertical structure of atmospheric tempera-ture profilesusing oxygen absorption in the 50-60 GHz frequency range.Since 2008,MWTS and its improved in-struments have been deployed on FY-3A satellite(2008),FY-3B satellite(2010),FY-3C satellite(2013),and FY-3D satellite(2017),accumulating over a decade of observational data.While many researchers have utilized historical data from MSU and AMSU to study upper atmospheric trends,long-term datasets of high-altitude brightness temperatures incorporating data from domestic satellites remain scarce.The reliability of these domestic satellite datasets is crucial for constructingsuch long-term records.Therefore,this study assesses the quality of the FY-3 MWTS data by comparing them with synchronous observations from other instruments,such as METOP-A and Suomi-NPP.Our analysis shows that the average biases in the middle and upper tropospheric channels(53.596 GHz)between FY-3A/B/C/D and other instruments have been significantly reduced post-calibration,from-1.667 9/-1.215 6/-2.266 4/-0.019 4 K to-0.009 7/0.007 7/0.008 6/0.055 4 K,respectively.The standard deviations have also improved,reducing from 0.474 2/0.470 4/0.373 6/0.442 0 to 0.164 6/0.208 0/0.287 5/0.241 6,respectively.For the lower stratospheric channels(57.290 GHz),the average biases were re-duced from 0.236 4/0.567 5/-3.933 3/0.218 8 K to-0.101 3/-0.222 0/0.053 3/-0.033 2 K,respectively,and the standard deviations from 0.875 0,1.344 0,0.230 8,1.074 2 to 0.690 6,0.783 4,0.277 4,0.178 1,re-spectively.These results indicate a steady improvement in the detection performance of MWTS onboard FY-3A/B/C/D satellites.The recalibrated datasets effectively address issues such as abnormal data jumps during satellite orbits,radiation response decay in remote sensing instruments,and calibration differences between various satellites.The deviations between recalibrated data and references are within±0.1 K in both tropospheric and stratospheric channels.Furthermore,we conducted a differential analysis between the recalibrated FY-3D MWTS data and the long-term dataset from the NOAA Satellite Applications and Research Center(STAR).The monthly mean brightness temperature time series in the middle and upper tropospheresshows a minimal difference of 0.002 4 K/a in the trend of brightness temperature change.The brightness temperature distributions of both datasets are similar,de-creasing gradually from the equator to the poles,influenced by underlying surface types.The maximum difference in brightness temperature change trends is within±0.5 K/a.In the lower troposphere,the monthly mean brightness temperature time series shows a 0.0144 K/a differ-ence in the trend.The brightness temperature distributions of both datasets are similar,increasing gradually from the equator to the poles,and are almost unaffected by underlying surface types.The maximum difference in bright-ness temperature change trends is within±0.5 K/a.Therefore,the recalibrated FY-3D data post-2020 can be combined with the STAR dataset for analyzing tem-perature changes in the middle and upper atmosphere.This study supports climate change research based on long-term historical data from domestic satellites.
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