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- Title
Magnitude and variability of land evaporation and its components at the global scale.
- Authors
Miralles, D. G.; De Jeu, R. A. M.; Gash, J. H.; Holmes, T. R. H.; Dolman, A. J.
- Abstract
A process-based methodology is applied to estimate land-surface evaporation from multi-satellite information. GLEAM (Global Land-surface Evaporation: the Amsterdam Methodology) combines a wide range of remotely-sensed observations to derive daily actual evaporation and its different components. Soil water stress conditions are defined from a root-zone profile of soil moisture and used to estimate transpiration based on a Priestley and Taylor equation. The methodology also derives evaporationfrom bare soil and snow sublimation. Tall vegetation rainfall interception is independently estimated by means of the Gash analytical model. Here, GLEAM is applied daily, at global scale and a quarter degree resolution. Triple collocation is used to calculate the error structure of the evaporation estimates and test the relative merits of two different precipitation inputs. The spatial distribution of evaporation - and its different components - is analysed to understand the relative importance of each component over different ecosystems. Annual land evaporation is estimated as 67.9x10³ km³3, 80% corresponding to transpiration, 11% to interception loss, 7% to bare soil evaporation and 2% snow sublimation. Results show that rainfall interception plays an important role in the partition of precipitation into evaporation and water available for runoff at a continental scale. This study gives insights into the relative importance of precipitation and net radiation in driving evaporation, and how the seasonal influence of these controls varies over different regions. Precipitation is recognised as an important factor driving evaporation, not only in areas that have limited soil water availability, but also in areas of high rainfall interception and low available energy.
- Subjects
EVAPORATION (Meteorology); REMOTE sensing; SOIL moisture; METEOROLOGICAL precipitation; RUNOFF; SOIL structure; HYDROLOGIC models
- Publication
Hydrology & Earth System Sciences, 2011, Vol 15, Issue 3, p967
- ISSN
1027-5606
- Publication type
Article
- DOI
10.5194/hess-15-967-2011