Effect of Water Surface Salinity on Evaporation: The Case of a Diluted Buoyant Plume Over the Dead Sea

Abstract

Evaporation from water bodies strongly depends on surface water salinity. Spatial variation of surface salinity of saline water bodies commonly occurs across diluted buoyant plumes fed by freshwater inflows. Although mainly studied at the pan evaporation scale, the effect of surface water salinity on evaporation has not yet been investigated by means of direct measurement at the scale of natural water bodies. The Dead Sea, a large hypersaline lake, is fed by onshore freshwater springs that form local diluted buoyant plumes, offering a unique opportunity to explore this effect. Surface heat fluxes, micrometeorological variables, and water temperature and salinity profiles were measured simultaneously and directly over the salty lake and over a region of diluted buoyant plume. Relatively close meteorological conditions prevailed in the two regions; however, surface water salinity was significantly different. Evaporation rate from the diluted plume was occasionally 3 times larger than that of the main salty lake. In the open lake, where salinity was uniform with depth, increased wind speed resulted in increased evaporation rate, as expected. However, in the buoyant plume where diluted brine floats over the hypersaline brine, wind speed above a threshold value (∼4 m s−1) caused a sharp decrease in evaporation probably due to mixing of the stratified plume and a consequent increase in the surface water salinity.

Seasonal dynamics of internal waves governed by stratification stability and wind: Analysis of high‐resolution observations from the Dead Sea

“…). The wind at the Dead Sea is characterized by a diurnal cycle with northerly winds at night ( <8 m s −1 ) and relatively calm daytime winds during the warm season (Hecht and Gertman ; Hamdani et al ; Lensky et al ; Mor et al ). In response to the intense northerly winds, there is a setup in the lake level at the southern end of the lake, as is seen in Fig.…”

Spatial Non-Uniformity of Surface Temperature of the Dead Sea and Adjacent Land Areas

“…Specifically, in the Dead Sea, at a depth of 2 m, solar radiation is only~10% of its surface value [2]. As a result, in the daytime in the summer months, a thermocline (thermal layering) is created from the water surface down to a depth of 3-4 m, based on buoy measurements in the Dead Sea [3,4]. For comparison, in the fresh-water Sea of Galilee (with the same level of solar radiation) water temperature hardly changes even to a depth of 15 m [5,6].…”

Discharge estimation of submarine springs in the Dead Sea based on velocity or density measurements in proximity to the water surface

“…The rate of evaporation from such a saline lake is difficult to determine accurately; it has been estimated to be 0.99–1.15 m/year (Lensky et al, ; Metzger, Nied, Corsmeier, Kleffmann, & Kottmeier, ; Stanhill, ). The evaporation rate near a buoyant plume generated by SGD is much higher than over the general surface of the Dead Sea (Mor, Assouline, Tanny, Lensky, & Lensky, ), but the affected areas are small relative to the area of the Dead Sea. The processes about which little is known in the water budget of the Dead Sea are the rate of evaporation and SGDs (Siebert et al, ).…”