Estimation of land surface directional emissivity in mid-infrared channel around 40 µm from MODIS data

Abstract

This work addressed the estimate of the directional emissivity in the mid-infrared (MIR) channel around 4.0 microm from MODIS data. A series of bidirectional reflectances in MODIS channel 22 (3.97 mum) were retrieved using the method developed by Tang and Li (Int. J. Remote Sens. 29, 4907, 2008) and then were used to estimate the directional emissivity in this channel with the aid of the BRDF model modified by Jiang and Li (Opt. Express 16, 19310, 2008). To validate the estimated directional emissivity, a cross-comparison of MODIS derived emissivities in channel 22 using the proposed method were performed with those provided by the MODIS land surface temperature/emissivity product MYD11B1 data. The results show that the proposed method for estimating the directional emissivity in MIR channel gives results comparable to those of MYD11B1 product with a Mean Error of -0.007 and a Root Mean Square Error of 0.024.