Location: Hydrology and Remote Sensing Laboratory
Title: Generating 30-m land surface albedo by integrating landsat and MODIS data for understanding the disturbance evolution Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 23, 2012
Publication Date: July 27, 2012
Citation: Shuai, Y., Masek, J., Gao, F.N., Schaaf, C., Williams, C. 2012. Generating 30-m land surface albedo by integrating landsat and MODIS data for understanding the disturbance evolution[abstract]. IEEE Geoscience and Remote Sensing Symposium. 2012 CDROM. Technical Abstract: Land cover changes affect climate through both biogeochemical (carbon-cycle) impacts and biogeophysical processes such as changes in surface albedo, temperature, evapotranspiration, atmospheric water vapor, and cloud cover. Recent studies have examined both the greenhouse gas and biophysical consequences of land use change in order to understand which may dominate in any particular area. There is a need for improved estimates of land surface albedo to fully understand the role of land cover change in climate forcing. The Moderate Resolution Imaging Spectroradiometer (MODIS) reflectance anisotropy and albedo products have been providing global Bidirectional Reflectance Distribution Function (BRDF) models, albedo measures, and nadir BRDF-adjusted surface reflectances (NBAR) at 500-meter spatial resolution since 2000. These products serve as key inputs to initialize and evaluate surface radiation schemes in climate models. However, past studies on post-disturbance albedo have been limited by the resolution of available MODIS data (500m), which is significantly coarser than the characteristic scales of ecosystem disturbance and human land use. Our on-going project addresses this issue by creating Landsat-resolution (30m) albedo maps through the fusion of Landsat TM/ETM+ directional reflectance with MODIS BRDF/Albedo (MCD43A) data. A recently developed “concurrent” approach required simultaneous acquisitions from Landsat and MODIS. In this paper, we expanded the approach by using a classification-based Look-Up-Table (LUT) to associate BRDF parameters based on land cover type and thus extended Landsat resolution albedo record before 2000. These maps in fine resolution permit trends in albedo to be evaluated at the characteristic scale of vegetation change (~1 ha). In addition, these high-resolution albedo products can be combined with Landsat-based records of land cover change and ecosystem disturbance in order to quantify the evolution of albedo during disturbance and post-disturbance recovery. Future work will expand the study area to include the full range of North American vegetation regimes. We intend to evaluate the net change in both winter and summer albedo across the continent due to land cover change processes occurring since the 1970’s. This information will also feed into a global analysis of albedo changes occurring since the 1700’s parameterized using the IPCC Global Land Use harmonization data set.