瞿建华,张烺. 2019. 基于ERA5的RTTOV辐射传输模拟与FY-4A成像仪 观测结果的偏差分析[J]. 气象学报, (0):-, doi:10.11676/qxxb2019.049
基于ERA5的RTTOV辐射传输模拟与FY-4A成像仪 观测结果的偏差分析
Characterization of bias of FY-4A advanced geostationary radiation imager observations from ERA5 background simulations using RTTOV
投稿时间:2018-05-29  修订日期:2019-03-13
DOI:10.11676/qxxb2019.049
中文关键词:  辐射传输模式,静止轨道卫星,成像仪
英文关键词:Radiative transfer model, Geostationary satellite, Radiation imager
基金项目:
作者单位E-mail
瞿建华 中国气象局北京华云星地通科技有限公司 Qujh@cma.gov.cn 
张烺 中国气象局北京华云星地通科技有限公司 zhanglang@itpcas.ac.cn 
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中文摘要:
      于2016年12月发射升空的FY-4A是我国第二代静止轨道卫星,该星上搭载了可提供东半球近实时高分辨率卫星观测数据的扫描辐射成像仪——AGRI。[目的]在其观测数据应用于大气参数反演或同化前,数据偏差的定量化分析是一个必要环节。[资料和方法]该文采用快速辐射传输模式RTTOV,基于ERA5再分析资料对AGRI的七个红外通道进行了模拟,并利用MODIS云检测产品对模拟结果进行了晴空筛选,以期得到一些对AGRI的定量应用有价值的偏差分析结果。观测-模拟(O-B)的偏差分析结果显示:[结果]海洋和陆地上,10通道(7.1μm)存在明显大于其它红外通道的系统性偏差,[结论]这很可能来源于欧洲中期天气预报中心(ECMWF)第五个全球再分析数据产品(ERA5)在对流层中层对水汽的高估。08通道为近红外短波通道,地表反射作用影响强烈,陆地上存在较大的平均偏差,而海洋上平均偏差小于0.4K。14通道在ERA5近地层气温偏高及定标偏差的影响下,海洋存在接近1K的平均偏差;陆地上存在2K左右的平均偏差。[结果]其余各红外通道在海洋和陆地上的平均偏差分别在0.6K和1.3K以下。偏差影响因子分析结果显示:[结果]地表海拔高度、观测天顶角对偏差也存在一定程度的影响;[结论]海洋上偏差分布存的季节变化可能来源于再分析资料中海表温度估算的季节性误差。
英文摘要:
      The next-generation geostationary satellite FY-4A equipped with advanced geostationary radiation imager (AGRI) was launched on 11th Dec 2016. In this study, the biases of 7 infrared channels (8-14 channel) of AGRI from the model simulations are characterized by using the Radiative Transfer for the TIROS Operational Vertical Sounder(RTTOV). The Moderate-Resolution Imaging Spectroradiometer (MODIS) cloud mask is used for selecting clear-sky data. The significant systematic deviation at channel 10 (7.1μm) most probably caused by the overestimation of water vapor in ERA5 (the fifth ECMWF reanalysis) data. The calibration error and higher air temperature of surface layer in ERA5 data are possible causes of channel 14 (13.5μm). Since the brightness temperature of near-infrared channel (channel 08 3.72μm) is affected by surface reflection strongly, there is a large average bias on the land at channel 08. The biases of this channel over ocean is less than 0.4K. The average biases at all other infrared channels over ocean and land are below 0.6K and 1.3K respectively. In addition, the surface altitude and the sensor zenith also have a certain degree of influence on the simulation and then lead to a corresponding bias characteristic. The seasonal variation of bias distribution over ocean exists at channel 11 (8.5μm), 12 (10.8μm) and 13 (12.0μm) probably come from the seasonal error of sea surface temperature estimation in the reanalysis data.
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