A biophysical process-based estimate of global land surface evaporation using satellite and ancillary data - II. Regional and global patterns of seasonal and annual variations

A process-based biophysical model of evaporation described previously was run using spatially representative data to calculate global fields of monthly total transpiration, soil evaporation and interception for a period of 24 months (January 1987 to December 1988). Solution of the energy balance equation provided net radiation and sensible heat flux, complementing the evaporative flux. The zonally averaged (area weighted 5 degrees latitude bands) values of annual total evaporation and evaporative fraction (ratio of evaporation and net radiation) are in broad agreement with previous estimates. Transpiration was found to be the dominant component of annual total evaporation in 20 out of the 28 latitude bands. partitioning of annual total evaporation over the global land area is calculated to be, 52% transpiration, 28% soil evaporation and 20% interception. Seasonal variations of total evaporation and its components are presented for some specific types of vegetation (e.g., tundra, taiga, rainforest, crop land) and compared with field observations. (C) 1998 Elsevier Science B.V. All rights reserved.