Aircraft measurements of surface albedo in relation to climatic changes in southern Israel

Recent studies imply that significant climatic changes over the central and southern coastal plain in Israel may be due to changes in land usage, which have taken place since the National Water Carrier operation in the early 1960's. Such changes are reflected in the spatial distribution of the surface albedo pattern, obviously resulting in changes in the surface radiation balance and, subsequently, modifying the surface heat fluxes and the stability conditions of the Planetary Boundary Layer (PBL). An Eppley PSP Pyranometer facing downward was mounted on a small Cessna aircraft and flown along the coastal plain from Tel Aviv to the northern Negev south of Beer Sheva, at an altitude of approximately 500 feet, measuring surface reflection. The incoming solar radiation was measured simultaneously, at several surface radiation stations of the Israel Meteorological Service, along the flight path. The results show large differences in surface reflection distributions, between the cultivated areas in southern Israel (as low as 0.15), and the adjacent arid regions (with values of up to 0.35). Historical albedo maps were reconstructed according to land utilization maps of the 1930's and the 1960's. A comparison between recent albedo map and the reconstructed maps, indicates temporal changes in the surface albedo pattern during the last decades.