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引用本文:

DOI:

10.11834/jrs.20221446

收稿日期:

2021-06-29

修改日期:

2022-04-09

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基于微波辐射计响应特性的FY-3C微波湿度计历史数据一致性定标方法(国产遥感卫星历史数据再定标共性技术)
王振占, 肖雨伟, 王可昕, 张升伟
中国科学院国家空间科学中心 中国科学院微波遥感技术重点实验室
摘要:

星载微波湿度计观测的地球表面和大气的微波辐射数据是数值天气预报和气候研究的重要基础数据源。由于微波湿度计系统响应特性差异、在轨工作条件的变化,以及星上定标基准的差异,不同微波湿度计、同一微波湿度计数据之间在长时间范围内都存在一定的偏差。如果这些偏差不进行修正,则会对长时间序列应用(如气候研究等)具有较大的影响,甚至可能导致错误的结果。并且由于微波辐射不存在绝对基准,无法通过绝对基准的传递进行星上数据的绝对定标,因此需要利用其它相对定标方法对湿度计的稳定性及其变化特征进行评价。本文基于OMB定标的思想,获得OMB定标偏差后,结合微波湿度计的系统响应特性和星上定标基本原理,建立了微波湿度计定标偏差的校正模型—再定标模型,从而实现定标偏差的校正。初步研究结果表明:使用再定标模型后,FY-3C微波湿度计-II定标结果的时间序列稳定,原始OMB偏差中的各种异常波动现象得到良好修正。并且该模型是基于微波湿度计的系统响应特性,因此这一方法同样适用于其他FY-3系列卫星微波湿度计数据的定标偏差校正。当使用相同的辐射传输模型时,再定标模型可以实现FY-3系列卫星微波湿度计数据的一致性定标。

Recalibration MWHTS’ historical data onboard FY3C based on the response characteristics of microwave radiometer
Abstract:

The microwave radiation data of the earth"s surface and atmosphere observed by the spaceborne microwave radiometer are basic source for numerical weather prediction and climate research. Due to the difference of the response characteristics and of the calibration absolute reference between each sounder and variation of the on-orbit working conditions, there are certain bias between the data of different or the same radiometers over a long period of time. If these biases are not corrected, it will have significant implications for long time series applications (such as climate studies), and may even lead to erroneous results. In addition, it is impossible to perform absolute calibration of onboard data since the absolute reference for calibration is not clear. So it is necessary to use other relative calibration methods to evaluate the stability and variation characteristics of the radiometer. In this dissertation, in order to adjust the calibration biases, a correction model for the calibration biases of the microwave humidity sounder is established considering the principle of system responses and on-orbit calibration, which is also called re-calibration methods, based on OMB technique (observed brightness temperature (O) minus simulated brightness temperature (B)). Using the re-calibration methods, L1 level observation data of the FY-3C microwave humidity sounder was analysed and the re-calibration coefficients were calculated. Then, using two data sets, the re-calibration coefficients were verified. The residual and validation results show that the time series of recalibration results is stable, and some abnormal fluctuations in the original OMB biases have been well corrected after re-calibration, this means that the re-calibration methods is valid. And the method is based on the system responses of microwave humidity sounder, therefore, it is also applicable to other FY-3 series satellite microwave humidity sounder for calibration biases correction. When using the same radiative transfer (RT) model, this re-calibration methods can achieve consistent calibration of FY-3 series satellite microwave humidity sounder data.

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