Abstract. Increasing warming of steadily shrinking Dead Sea surface
water compensates for surface water cooling (due to increasing evaporation)
and even causes observed positive Dead Sea sea surface temperature trends. This
warming is caused by two factors: increasing daytime heat flow from land to
sea (as a result of the steady shrinking) and regional atmospheric warming.
Using observations from the Moderate Resolution Imaging Spectroradiometer (MODIS),
positive trends were detected in both daytime and nighttime Dead
Sea sea surface temperature (SST) over the period of 2000–2016. These
positive SST trends were observed in the absence of positive trends in
surface solar radiation, measured by the Dead Sea buoy pyranometer. We also
show that long-term changes in water mixing in the uppermost layer of the
Dead Sea under strong winds could not explain the observed SST trends. There
is a positive feedback loop between the positive SST trends and the
steady shrinking of the Dead Sea, which contributes to the accelerating decrease in
Dead Sea water levels during the period under study. Satellite-based SST
measurements showed that maximal SST trends of over 0.8 ∘C decade−1
were observed over the northwestern and southern sides of the
Dead Sea, where shrinking of the Dead Sea water area was pronounced. No
noticeable SST trends were observed over the eastern side of the lake, where
shrinking of the Dead Sea water area was insignificant. This finding
demonstrates correspondence between the positive SST trends and the
shrinking of the Dead Sea indicating a causal link between them. There are
two opposite processes taking place in the Dead Sea: sea surface warming and
cooling. On the one hand, the positive feedback loop leading to sea surface
warming every year accompanied by long-term increase in SST; on the other
hand, the measured acceleration of the Dead Sea water-level drop suggests a
long-term increase in Dead Sea evaporation accompanied by a long-term
decrease in SST. During the period under investigation, the total result of
these two opposite processes is the statistically significant positive sea
surface temperature trends in both daytime (0.6 ∘C decade−1) and
nighttime (0.4 ∘C decade−1), observed by the MODIS instrument.
Our findings of the existence of a positive feedback loop between the
positive SST trends and the shrinking of the Dead Sea imply the following
significant point: any meteorological, hydrological or geophysical process
causing the steady shrinking of the Dead Sea will contribute to positive
trends in SST. Our results shed light on continuing hazards to the Dead Sea.
Long-Term Sea Surface Temperature Variability along the U.S. East Coast
