基于风云卫星红外高光谱资料遥感逆温层研究

Retrieval and sensitivity analysis of the atmospheric inversion layer based on Fengyun satellite infrared hyperspectral data

  • 摘要: 大气逆温层会阻碍大气垂直运动的发展,传统上只能利用地基无线电探空资料进行监测和分析。星载高光谱红外大气探测可以反演晴空区大气温、湿度廓线,为大气逆温层监测提供了一种可能的技术手段。为探索中国卫星监测逆温层的方法和途径,本研究基于风云三号D星搭载的红外高光谱大气探测仪(FY-3D/HIRAS)观测资料,利用RTTOV(Radiative Transfer for TOVS)快速辐射传输模式模拟了不同逆温强度、不同逆温层顶高度对HIRAS红外通道观测亮温的影响。结果表明,在780—1000 cm−1窗区光谱内的精细谱线对应的通道对逆温层最为敏感,与参考通道(926.875 cm−1)的亮温差可以用于大气逆温层识别。文中定义了逆温强度敏感指数和逆温层顶高度敏感指数,模拟结果表明,强吸收(通道1:784.375 cm−1、通道2:798.750 cm−1)、中吸收(通道1:803.125 cm−1、通道2:852.500 cm−1)、弱吸收(通道1:840.000 cm−1、通道2:871.250 cm−1)通道的逆温强度敏感指数分别为0.49、0.48、0.30,逆温层顶高度敏感指数分别为0.045、0.036、0.018。基于强吸收通道观测亮温可以反演获得逆温强度和逆温层顶高度信息,且通道亮温与逆温强度的相关高于逆温层顶高度。研究结果验证了利用红外高光谱通道亮温数据研究逆温层结构的可行性,为后续逆温特征的反演工作提供了依据和参考。

     

    Abstract: Atmospheric inversion layer will hinder the development of vertical movement. Traditionally, only ground-based radiosonde data are used for monitoring and analyzing the atmospheric inversion layer. Spaceborne hyperspectral infrared atmospheric sounding can retrieve atmospheric temperature and humidity profiles in clear sky condition, which provides a possible technique for monitoring the atmospheric inversion layer. In order to explore the method of monitoring inversion layer using domestic satellite data, the RTTOV fast radiative transfer model is used to simulate the FY-3D/HIRAS observation spectrum, including the effects of different inversion strength and height of the inversion layer top on the brightness temperature observed by HIRAS. The results show that the channels corresponding to the fine spectral lines in the window region of 780—1000 cm−1 are most sensitive to the inversion layer, and the brightness temperature difference between the observed channel and the reference channel (926.875 cm−1) can be used to identify the atmospheric inversion layer. The sensitivity index of inversion strength and the sensitivity index of the height of the inversion layer top are defined in this study. Simulation results show that the sensitivity indices of inversion strength at strong absorption (784.375 cm−1, 798.750 cm−1), medium absorption (803.125 cm−1, 852.500 cm−1) and weak absorption (840.000 cm−1, 871.250 cm−1) channels are 0.49, 0.48 and 0.30, and the sensitivity indices of the height of the inversion layer top are 0.045, 0.036 and 0.018, respectively. Based on the brightness temperature of the strong absorption channels, the inversion strength and the height of the inversion layer top can be retrieved, and the correlation of the channel brightness temperature with inversion strength is higher than that with the height of the inversion layer top. The results verify the applicability of using infrared hyperspectral channel brightness temperature data to study the inversion layer structure, and provide a basis and reference for subsequent retrievals of the inversion characteristics.

     

/

返回文章
返回