Research Highlight: Global Land Surface Evaporation

Rate of Change of Global Land Surface Evaporation during the Past 50 Years: Confirmed by Clausius-Clapeyron Scaling

Submitter: W. Brutsaert, School of Civil and Environmental Engineering, Cornell University, Ithaca, NY

Area of Research: Global scale hydroclimate

GEWEX Panel: Global Land/Atmosphere System Study (GLASS) Panel 

Journal Reference:
Brutsaert, W., 2016. Global land surface evaporation trend during the past half century: Corroboration by Clausius-Clapeyron scaling, Advances in Water Resources,

During the past several decades, evaporation from the Earth’s land surfaces has been increasing at a rate between roughly 0.4 and 0.5 mm a-2. This suggests that the hydrological cycle has generally been intensifying during this period.

This is one more confirmation of the counterintuitive notion that the general worldwide observations of decreasing evaporation from plants and of decreasing wind speeds are often a manifestation of increasing terrestrial evaporation in many regions.

Analyses of satellite data mainly over the world’s ocean surfaces have shown that during 1986–2006 global average values of atmospheric water vapor, precipitation and evaporation have increased at a relative rate of 0.0013a−1; this is roughly in accordance with the Clausius-Clapeyron equation for the average temperature trend during this period, and amounts to 0.065K−10.065K−1 at the average temperature of T=14∘C. Application of this concept over the world’s land surfaces yields an average global evaporation trend during the past half century of around 0.4 to 0.5 mma−2; this confirms the values obtained in previous studies with totally different methods.

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