FY-3A上搭载的中分辨率成像光谱仪(MERSI)和扫描辐射计(VIRR)都包含热红外通道,可用于地表温度的反演。结合热红外通道的光谱响应函数,用MODTRAN模拟清洁大气、城市气溶胶、乡村气溶胶和沙尘气溶胶条件下的亮温值,通过分裂窗算法求解不同气溶胶类型和光学厚度下的地表温度。结果表明:气溶胶类型和光学厚度之间的差异会造成热红外通道的亮温差发生变化,这一现象在VIRR的热红外通道表现得尤为显著。通过拟合系数和气溶胶光学厚度之间的关系建立新的反演算法,发现:在分裂窗算法基础上加入气溶胶光学厚度这一参量之后,地表温度反演的均方根误差有所降低,尤其是在气溶胶浓度高时改进效果更佳,其中对城市气溶胶这一类型改善效果明显(RMSE由0.814K下降到0.442 K,BIAS从0.998K降到0.668 K)。
Datas of thermal infrared channels from both FY-3A Moderate Resolution Imaging Spectroradiometer( MERSI) and Visible and Infrared Radiometer( VIRR) can be used for retrieving land Surface temperature( LST). Combination of spectral response function from thermal infrared channels,using MODTRAN to simulate the bright temperature under the conditions of clean air,urban aerosol,rural aerosol and dust aerosol,and calculating LST of different aerosol types and optical thickness based on split window algorithm. The results show that the differences between aerosol types and optical thickness will cause brightness temperature changes in the thermal infrared channel,especially in VIRR. Through the relationship between fitting coefficients and aerosol optical thickness,establishing a new retrieval algorithm. It 's found that adding split window algorithm with aerosol optical thickness can decrease root mean square error of LST,especially in the aerosol concentration is high,the effect is better. The effect of urban aerosol is improved obviously( RMSE decreases from 0. 814 K to 0. 442 K,and bias decreases from 0. 998 K to 0. 668 K).