Narrowband to broadband conversion of Landsat TM glacier albedos

In this paper we present an empirical relationship between the broadband gl acier albedo (a) and the narrowband glacier albedos in Landsat TM bands 2 a nd 4 (alpha(2) and alpha(4) respectively). The relationship was established on the basis of multiple linear regression analysis of 112 ground-based si multaneous measurements of alpha, alpha(2) and alpha(4) made at 32 sites on the tongue of the Morteratschgletscher, Switzerland. The measurements were carried out over a representative set of glacier surface types ranging fro m completely debris-covered glacier ice (alpha = 0.08) to dry snow (alpha = 0.86). The regression model explains more than 99% of the variance of the broadband albedo and the root-mean-square value of the residuals is only 0. 009. The relationship enables users of Landsat TM data to make an accurate estimate of the broadband albedo on the basis of narrowband albedos without having to classify the glacier surface.