קולוקוויום בחוג לגאופיזיקה: Spatial heterogeneity and trends of surface water temperature in the drying-up Dead Sea
Pavel Kishcha, TAU
The Dead Sea is a terminal hypersaline lake at a unique location at ~430 m below sea level. Over the last several decades the Dead Sea has been drying up due to climate change in the Eastern Mediterranean causing an imbalance between water inflow and evaporation in the Dead Sea. As a result, Dead Sea water levels decrease. This contributes to the shrinking of the Dead Sea water area. The process of steady Dead Sea shrinking initiates a positive feedback loop between the shrinking of the Dead Sea and the increasing sea surface temperature (SST) trends. This positive feedback loop together with atmospheric warming causes increasing warming of surface water. Using observations from MODIS, positive trends were detected in both daytime and nighttime Dead Sea SST over the period of 2000 – 2016. Satellite data on board Terra, Aqua, and METEOSAT satellites showed the presence of pronounced spatial heterogeneity in daytime Dead Sea surface temperature: SST at the east side of the lake exceeded by several degrees SST at the middle and west parts. METEOSAT geostationary satellite data (2005-2015) showed that spatial heterogeneity in SST was pronounced throughout the daytime. It is important to highlight that this was observed under uniform solar radiation in the summer months. The spatial heterogeneity in daytime SST caused a pronounced asymmetry in land surface temperature between land areas adjacent to the east and west sides of the lake.
A specific feature of the hypersaline Dead Sea is strong non-linear absorption of solar radiation, in contrast to fresh-water lakes. In the presence of water mixing, the maximum of SST should be observed several hours later than that of land surface temperature (LST) due to high heat capacity of bulk water. However, METEOSAT showed that, in summer, SST peaked at the same time, 13 LT, as LST over surrounding land areas. This fact is evidence that there was no noticeable vertical water mixing. In the absence of that, evaporation was the main causal factor of the observed spatial heterogeneity in Dead Sea SST. Maximal evaporation (causing maximal surface water cooling) took place at the middle part of the Dead Sea, while minimum evaporation took place at the east side of the lake.
Reference: Kishcha P. and Starobinets B. (2021). Spatial heterogeneity in Dead Sea surface temperature associated with inhomogeneity in evaporation. Remote Sensing, 13(1), 93; https://doi.org/10.3390/rs13010093.
מארגני האירוע: ד"ר רועי ברקן וד"ר אסף ענבל