Characteristics of the summer 3-D katabatic flow in a semi-arid zone—The case of the Dead Sea

The katabatic winds have been studied over the slopes surrounding the Dead Sea (DS, in brevity), located at altitude of 433 m below sea level focusing on the summer season when the katabatic winds are most frequent, persistent and pronounced due to the summer stable weather conditions. The study observes the katabatic wind pulses, which are intermittent, via 3-D innovative measurement tools with high time and space resolution employing Energy Balance Stations, Radiosondes and Lidars. The nocturnal katabatic pulses were investigated employing vertical depth, wind direction/intensity, duration, number of pulses and the time intervals separating them, as well as the begin and termination times during August 2014. The average direction of the pulses depends on the nearby slopes orientations while the intensity depends on the station's elevation and its location relative to the slope. The average katabatic number of pulses, duration, time intervals and their beginning and terminating times were found to strongly depend on the other local flows. The average vertical depth of the katabatic layer from both sides of the DS, in Israel and Jordan, was found to be at 450–950 m above ground level, depending on the measurement time period as well as the tools' sensitivities employing the “KIT cube system”—an advanced integrated atmospheric observation system, which allows 3-D accurate analysis of the detailed katabatic wind pulses over the DS. The average number of the katabatic pulses was found to be ~2.9–3.5 pulses·night⁻¹. The average duration of each pulse was ~69–94 min and the time interval separating them ~32–44 min depending on the flows which interrupt the pulses. The starting time of first katabatic pulse in local time was 0113 LST (±0119). These findings are of great relevance for the DS evaporation as well as bio-meteorological and pollution aspects.