Simulation of Directional Emission from Vegetative Canopy using Monte-Carlo Method

Although directional measurements of brightness temperature has made by a number of satellite- based and airborne sensors for a long time, interpretation of such measurements is a difficult task due to the fact that surface radiometric temperatures are resulted from energy balances in multi-scales from leaf and soil to the top of canopy or pixel. In this paper, a non-isothermal Monte-Carlo method based algorithm was proposed to model the angular emission from vegetative canopy and scale radiometric temperatures of foliage and soil to the top of canopy. This approach allows an accurate simulation of multi-reflection between foliage layers, foliage layer and soil surface, and foliage layers and sky, as well as the non-isothermal condition within canopy and between canopy layers and soil surface. Field measurements of directional thermal infrared radiation, which were collected in the Shunyi remote sensing campaign in Shunyi, Beijing in 2001 was used to preliminarily validate this non-isothermal Monte-Carlo algorithm. A reasonable agreement was archived from this validation.