Albedo Trends Related to Land Cover Change and Disturbance: a Multi-Sensor Approach
Hydrology and Remote Sensing Laboratory
2012 Annual Report
1a.Objectives (from AD-416):
The overall objective for this project is to better quantify albedo changes associated with land cover change, vegetation disturbance, and recovery from disturbance by fusing Moderate Resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF)/Albedo and Landsat directional reflectance observations. There are four separate objectives for this project. This project focuses on objective 1 to create a global lookup table of albedo values as well as BRDF parameters for typical land cover types, as a function of global ecoregion. The accumulated BRDF parameters for different crop types will be used to correct directional effects from wide-swath satellite data such as MODIS, Advanced Very High Resolution Radiometer (AVHRR) and Advanced Wide Field Sensor (AWiFS) observations.
1b.Approach (from AD-416):
ARS will provide global MODIS BRDF/albedo data and Landsat data, and existing computer programs for analysis. The Cooperator will use the 2000 and 2005 Global Land Survey (GLS) Landsat dataset to select “pure” homogeneous MODIS pixels globally. The pure MODIS samples will be used to compute mean per-class albedos and their variance. The BRDF/albedo results from these pure MODIS pixels will be assembled into a per-class Look-Up Table (LUT), and analyzed and applied to correct BRDF effects from wide-swath satellite data.
The goal of this project is to work with scientists from University of Maryland to build a global albedo look-up table (LUT) for climate and energy balance modeling in support of ARS effort to develop remote sensing and modeling approaches for monitoring the magnitude of agricultural drought and its subsequent impact on agricultural crop condition and yield.
In order to build a global albedo LUT, scientists at University of Maryland have downloaded and processed MODIS global albedo products from 2000 to 2011. A beta version of global snow-free albedo look-up table (LUT) has been created. Initial results from albedo LUT have been tested and compared. The snow-cover albedo LUT is under construction in the University of Maryland’s computing facilities. The results will be delivered to ARS and NASA for integration with climate and energy balance models.