ARM Science Team Meeting

1. sgpsurflogC1 : 10m = brown sgpsurflogC1: 10m = lush green sgpsurflogC1: 10m = lush green sgpsurflogC1: 25m = green ground covered sgpsurflogC1: 25m = stubble after harvest sgpsurflogC1: 25m = green ground covered • Determining Surface Type Surface Type Test Criteria Surface Type if (alb1 > 0.17 && alb3/alb5 >0.65) snow if(NDVI of alb5 and alb4 > 0.7) lush, green vegetation else if (NDVI of alb5 to abl4 > 0.31) partial vegetation else bare soil or brown vegetation • Normalized Difference Vegetation Index (NDVI) = (NIR – RED)/(NIR + RED) • For partially vegetated cases, percent vegetation was determined by linearly interpolating between the avg 0% to avg 100% NDVI values. NDVI of 870nm and 673nm Albedos for Full Vegetation and Bare Soil • Surface Type Classification Categories Confirmation of Lush Vegetation Spectral Albedo Curves for Surface Types Frequently Found at SGP Bare Soil Due to Wheat Harvest • Categories Identified for SGP Site • bare soil or no green vegetation • thick, lush green vegetation • partially covered soil or partially green vegetation • snow Bare Soil and Wheat in Winter Identification and Use of Surface Type to Estimate Spectral Albedo Using ARM MFR DataKrista L. Gaustad, Sally A. McFarlane, Charles N. Long, and Tim Shippert, Pacific Northwest National LaboratoryEli Mlawer, Atmospheric & Environmental Research, Inc. • Summary • Using the MFR spectral albedo values, surface conditions near the 10m and 25m towers can be characterized as one of the following: snow, bare soil, fully vegetated, or partially vegetated. • Predictions of the existence and extent of vegetation are made using the NDVI of the 870nm (filter5) and 673nm (filter4) albedos. • Estimations of high resolution spectral albedos made using surface type and MFR spectral albedo values were relatively successful for bare soil and fully vegetated cases. • Improvements are needed in the estimation of surfaces characterized by snow and partially vegetated surface types. Spectral Albedo Estimations • Estimations made using various techniques based on the spectral characteristics in a given wavelength • Tested against spectral albedo measurements taken at SGP by A. Trishchenko • Partial vegetation estimated for each surface type individually, weighting for mix as appropriate and summing results • Improvements may be possible through modifications to either the spectral albedo algorithm and/or the surface type function Lush Green Vegetation, 100% Vegetation Bare soil, 0% Vegetation, Brown Vegetation Partial Vegetation, Poor Agreement Partial Vegetation, Good Agreement Snow Ice 11 March 2008 ARM Science Team Meeting