Land Surface–Induced Regional Climate Change in Southern Israel

Abstract

Since the mid-1960s, the southern part of Israel has experienced major land use changes following the start of the irrigation scheme and the subsequent intensification of agricultural practice. Several studies, mainly based on the analysis of climatic time series, have shown that this has been followed by a significant change of the local climate, especially during the summer and early fall. They indicate a reduced diurnal amplitude of surface air temperature and wind speed, and a threefold increase of the October (early wet season) convective precipitation. In this paper, these phenomena are investigated by simulating the influence of the land surface on local meteorological variables with a two-dimensional version of a mesoscale atmospheric model containing a detailed land surface scheme. Particular attention is given to the correct estimation of land surface parameters from soil and vegetation maps and remote sensing data. The simulations confirm the observed reduction of the diurnal amplitude of temperature and wind speed when replacing a semiarid surface by a partly irrigated one. Furthermore, it is shown that the potential for moist convection increases with the surface moisture availability and is rather insensitive to the surface roughness.