Impacts of atmospheric near-surface stability on the Arctic summer
air-sea heat budget assessed with uncrewed surface vehicles
Abstract
The atmospheric marine boundary layer (AMBL) plays a crucial role in
regulating air-sea interactions and influencing the climate system,
particularly in the Arctic due to its high sensitivity to global
warming. This study utilizes five years (2018-2022) of saildrone data
from the Bering-Chukchi-Beaufort Seas to analyze atmospheric
near-surface stability and air-sea turbulent heat fluxes during the
Arctic summer. By applying Monin-Obukhov similarity theory (MOST), we
investigate the temporal variability and mechanisms that influence AMBL
stability. Our findings reveal two distinct regimes of stable and
unstable conditions in two contrasting years of 2020 and 2022. In 2020,
cold air advection driven by northerly winds consistently destabilizes
the AMBL, leading to increased oceanic heat loss. In 2022, however,
southerly winds and warm air advection stabilize the AMBL, suppressing
air-sea heat exchanges. The temporal variation of turbulent heat fluxes
is primarily driven by air-sea temperature differences, with the
magnitude of wind speed and its temperature covariance serving as
secondary factors. We also show the importance of skin temperature
measurements from saildrones for improving estimates of turbulent heat
fluxes. These insights enhance our understanding of Arctic air-sea
interactions and inform climate models, underscoring the need for
high-resolution observations in polar regions and the improvement of
bulk flux parameterization for stable AMBL.