Abstract

Land surface hemispherical albedos of several targets have been resolved using the bidirectional reflectance factor (BRF) library of the Finnish Geodetic Institute (FGI). The library contains BRF data measured by FGI during the years 2003–2009. Surface albedos are calculated using selected BRF datasets from the library. Polynomial interpolation and extrapolation have been used in computations. Several broadband conversion formulae generally used for satellite based surface albedo retrieval have been tested. The albedos were typically found to monotonically increase with increasing zenith angle of the Sun. The surface albedo variance was significant even within each target category / surface type. In general, the albedo estimates derived using diverse broadband conversion formulas and estimates obtained by direct integration of the measured spectra were in line.

Highlights

  • IntroductionSurface hemispherical albedo is one of the Essential Climate Variables (ECV) defined by the Implementation Plan for the Global Observing System for Climate in Support of the United Nations

  • Surface hemispherical albedo is one of the Essential Climate Variables (ECV) defined by the Implementation Plan for the Global Observing System for Climate in Support of the United NationsFramework Convention on Climate Change (UNFCCC)

  • This paper studies the effectiveness of various narrowband to broadband conversion algorithms

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Summary

Introduction

Surface hemispherical albedo is one of the Essential Climate Variables (ECV) defined by the Implementation Plan for the Global Observing System for Climate in Support of the United Nations. Framework Convention on Climate Change (UNFCCC) (http://unfccc.int/2860.php). It indicates how large a part of the incident radiation to a surface is reflected back. The albedo of land surfaces has large daily and seasonal variation in many regions. It depends on the solar zenith angle. This dependence is qualitatively known and several models exist, systematic measurement data from well defined targets are rare. Climate models require the land-surface albedo to be known at a quite high absolute accuracy, from

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