Regional Water Vapor sources for the Euphrates-Tigris watershed.

Given the massive changes in land cover occurring in the Middle East there is potential for significant feedbacks on the regional atmospheric circulations and precipitation. This study attempts to quantify the importance of different parts of the region to the production of precipitation in the Euphrates-Tigris watershed. A back-trajectory model is run to calculate the spatial water vapor contributions to the 300 largest precipitation events occurring from 1999 through 2004. The input data for the back-trajectory model is supplied by an MM5 simulation over the region. The method allows quantitative estimates of within watershed precipitation recycling as well as the water vapor contributions from surrounding land areas and large water bodies.