中红外大气强吸收通道的地表辐亮度图像模拟

Radiance image simulation at the bottom of atmosphere in mid-infrared absorption bands

针对SPIRIT-Ⅲ遥感器的2个4.3μm强吸收通道,以邻近4.3μm的MODIS第23通道图像为数据源,进行地表辐亮度图像模拟。首先,通过建立通道转换模型生成强吸收通道的地表发射率图像;然后,基于已有的中红外辐射传输解析模型,推导获得4.3μm吸收通道的地表辐亮度解析模型,基于地表的解析模型和辐射传输模型MODTRAN的模拟数据,提出吸收通道的大气效应参数计算方法;最后,基于地表辐亮度解析模型,综合发射率和温度图像、大气效应参数、以及通道响应函数实现2个吸收通道的地表辐亮度图像模拟。对模拟数据进行精度评价,结果表明地表发射率模拟误差不超过±6%,地表辐亮度模拟误差不超过±0.02%。由此可见,本文提出的4.3μm强吸收通道的地表辐亮度图像模拟方法可行,能够为该吸收通道的入瞳辐亮度图像和遥感器成像过程模拟提供地表辐射数据支撑。

This method was illustrated by applying it to simulating bottom-of-atmosphere( BOA) radiance for two4. 3 μm absorption bands of the SPIRIT-Ⅲ sensor by using MODIS data of band 23,which is close to 4. 3 μm.First,surface emissivity images in these two 4. 3 μm absorption bands were simulated using band translation models. Second,analytic model of BOA radiance was deduced based on an existing analytic model in mid-infrared bands,and then it was combined with simulations from radiative transfer model MODTRAN to calculate parameters of the atmospheric effects for these 4. 3 μm absorption bands. Finally,based on the proposed analytic model,BOA radiance in SPIRIT-Ⅲ 's two absorption bands can be generated from surface emissivity,temperature,atmospheric effect parameters and SPIRIT-Ⅲ's spectral response functions. Accuracy assessment on the simulation results shows that this method can produce surface emissivity and BOA radiance with errors less than6% and 0. 02%,respectively. Therefore,the method proposed in this paper can effectively and precisely simulate BOA radiance for the 4. 3 μm absorption bands,and provide radiance datasets for the at-sensor radiance simulation and sensor imaging simulation.