Meltwater lenses over the Chukchi and the Beaufort seas during summer
2019: from in-situ to synoptic view.
Abstract
We investigate the Chukchi and the Beaufort seas, where salty and warm
Pacific Water flows in from the Bering Strait and interacts with the sea
ice, contributing to its summer melt. For the first time, thanks to
in-situ measurements recorded by two saildrones deployed during summer
2019 and refined sea ice filtering in satellite L-Band radiometric data,
we demonstrate the ability of satellite Sea Surface Salinity (SSS)
observed by SMOS and SMAP to capture very fresh SSS anomalies induced by
sea ice melt, referred to as meltwater lenses (MWL).
The largest MWL observed by the saildrones during this period occupied a
large part of the Chukchi shelf, with an anomaly of SSS reaching -5pss,
and persisted for up to one month. Over this MWL, currents and wind
speed measurements illustrate the influence of induced low SSS pattern
on the air-sea momentum transfer to the upper ocean.
Combined with satellite-based Sea Surface Temperature, satellite SSS
provides a monitoring of the different water masses encountered in the
region during summer 2019. Using sea ice concentration and estimated
Ekman transport, we analyse the spatial variability of sea surface
properties after the sea ice edge retreat over the Chukchi and the
Beaufort seas. The two MWL captured by both, the saildrones and the
satellite measurements, result from different dynamics. Over the
Beaufort Sea, the MWL evolution followed the meridional sea ice retreat,
whereas in the Chukchi Sea, a large persisting MWL is generated by the
advection of a thin sea ice filament.