Numerical estimation for greening effect over desert in Saudi Arabia

The effect of desert greening over Saudi Arabia on the regional climate was estimated by the Meteorological numerical model (MM5) with a land surface model. Greening area has the range of 100km x 150 km, and at first it is pointed out the regional climate changes about rainfall, wind field, and water budget after consideration of the real climate around Saudi Arabia. The result of simulation after greening showed the increased rainfall around the coastal city, Jeddah, and it is clear that soil moisture under the greening area has little effect on the rainfall amount, but has a large effect on the latent heat flux and surface cloud water, so net rainfall, rainfall amount reduced by latent heat flux, falls to negative value in dry climate as February 2004. The net rainfall in a wet climate comes to be sufficiently large positive value, so it is showed the net rainfall amount increases due to a wet climate with the estimate of the total water budget including the advections of water vapor, rain and cloud water, rainfall, and latent heat flux. Additionally, the evergreen needle tree instead of the grass was adopted to greening, and the positive net rainfall was accomplished on the mountainous area.