两种高光谱热红外数据大气校正方法的分析与比较

Comparison of two methods for atmospheric correction of hyper-spectral thermal infrared data

利用模拟数据对Autonomous Atmospheric Compensation(AAC)和In-scene Atmospheric Compensation(ISAC)这两种高光谱热红外数据大气校正方法进行了对比和分析。结果显示,在满足方法适用条件情况下,AAC方法大气校正精度较高,除湿热的热带大气外,大气透过率的反演误差小于0.02,大气上行辐射的误差小于0.004W.m-2.sr-1.cm;而ISAC方法精度较低,透过率误差在0.05至0.3之间,上行辐射误差在0.003W.m-2.sr-1.cm至0.035W.m-2.sr-1.cm之间变化,误差随大气水汽含量增加而增加。大气非均一性对大气校正精度影响分析表明,AAC方法大气校正精度受大气非均一性影响显著。因此,需从高光谱数据光谱信息出发,发展针对低空间分辨率高光谱热红外数据的大气校正方法,以克服现有方法大气水平均一假设的不足。

Atmospheric correction is inevitable in estimating land surface temperature and land surface emissivity using hyper- spectral thermal infrared data. The Autonomous Atmospheric Compensation （AAC） and In-scene Atmospheric Compensation （ISAC） are the two main methods for atmospheric correction of hyper-spectral thermal data. Those two methods were applied to the simulated datasets. Results show that the high accuracy of the AAC method, except for the tropic atmosphere, and the root mean stand error （RMSE） of the transmittance and the up-welling radiance for the AAC method is less than 0.002 and 0.004 W.m^-2.sr^-1.cm, respectively. On the contrary, the error of the ISAC method is large, and the error of the transmittance var- ies from 0.05 to 0.3 and the error of the up-welling radiance changes from 0.003W.m^-2.sr^-1cm to 0.035 W.m^-2.sr^-1cm. The error increases as the increase of total precipitable water of the atmosphere. Analysis on the impact of heterogeneity of atmosphere on accuracy of atmospheric correction shows that the accuracy of AAC approach is influenced significantly by the heterogeneity of atmosphere. It is necessary to develop atmospheric correction methods for hyper-spectral thermal infrared data of low spatial resolution to overcome the drawback of requiring homogeneous atmosphere by existing atmospheric correction approaches.