Geosciences Dept. Seminar: Foehn-induced effects on dust pollution, frontal clouds and solar radiation in the Dead Sea valley

Abstract: 

Foehn-induced effects on dust pollution, frontal clouds and solar radiation were analyzed over the Judean Mountains (~1000 m) and over the Dead Sea valley (-420 m), using high-resolution numerical simulations and observations at meteorological stations located across the mountain ridge. Hot foehn winds created a pronounced temperature inversion over the western part of the valley. Strong foehn winds activated local dust sources, while the foehn-induced pronounced temperature inversion trapped dust particles beneath the inversion. These trapped local dust particles contributed to maximum surface dust concentration but not to dust aerosol optical depth (AOD) in the western Dead Sea valley. By contrast, in the central and eastern Dead Sea valley, in the absence of temperature inversion, the ascending airflow lifted dust particles up to 2-km altitude, contributing to the maximum local dust AOD. Thus, it was because of the temperature inversion in the western Dead Sea valley that the maximum surface dust concentration did not coincide with the maximum AOD: this being one of the specific effects of the foehn phenomenon on local dust pollution in the Dead Sea valley. Radar data showed a passage of frontal cloudiness through the area of the Dead Sea valley leading to a sharp drop in noon solar radiation (from 860 W m-2 to 50 W m-2). The strong descending airflow over the downwind side of the Judean Mountains led to the formation of a cloud-free band followed by a relatively slight increase in solar radiation in the presence of strong dust pollution.

Seminar Organizer: Prof. Eyal Haifetz