Components of near-surface energy balance derived from satellite soundings – Part 2: Latent heat flux

Abstract

This paper introduces a new method for recovering global fields of latent heat flux. The method focuses on specifying Bowen ratio fields through exploiting air temperature and vapour pressure measurements obtained from infra-red soundings of the AIRS 5 (Atmospheric Infrared Sounder) sensor onboard the NASA-Aqua platform. Through combining these Bowen ratio retrievals with satellite surface net available energy data we have specified estimates of global surface latent heat flux at the 1◦ by 1◦ scale. These estimates were evaluated against data from 30 terrestrial tower flux sites cover- ing a broad spectrum of biomes. Taking monthly average 13:30 LT this revealed a relatively good agreement between the satellite and tower measurements of latent heat flux, with a pooled root mean square devi- ation of 79Wm−2, and no significant bias. The results show particular promise for this approach under warm, moist conditions, but weaknesses under arid or semi-arid conditions subject to high radiative loads.