Climatic variations in the moisture and instability patterns of the atmospheric boundary layer on the east Mediterranean coastal plain of Israel

A long-term record (1964-1995) of radiosonde data observed at the Bet-Dagan aerological station of the Israel Meteorological Service was analyzed to d etect possible temporal trends in moisture content and instability of the a tmospheric boundary layer. Bet-Dagan is situated in the central part of the south-east Mediterranean coastal plain. During this period surface charact eristics in this region have changed drastically due to changes in land use , i.e., urbanization, development of irrigated agriculture and afforestatio n. The analysis of the radiosonde data reveals a clearly defined, statistic ally significant, increasing trend in the moisture content, mainly during s ummer. The stability of the surface layer, characterized by the bulk Richar dson Number, shows a decreasing trend since the early 1960s. Relationships between these trends, land-use modifications and possible influence of larg e-scale influence are discussed.