Oceanography Seminar Series
Yanxu Chen
Physics and Atmospheric Science
AV俱乐部
Title:
"A Stability-Controlled Switch in Arctic Air鈥揝ea Heat Flux"
Room Location: C236, LSC
Abstract:
The Arctic Ocean is accumulating heat at an unprecedented rate, yet most of that heat does not immediately escape to the atmosphere. What determines when and how the ocean finally releases this energy? Using five years of Saildrone uncrewed surface vehicle observations across the Bering, Chukchi, and Beaufort Seas, this seminar shows that the decisive control is atmospheric near-surface stability.
During summer, the Arctic atmospheric marine boundary layer is predominantly near-neutral, a regime in which traditional bulk flux algorithms鈥攄eveloped largely in tropical and mid-latitude conditions鈥攕how their largest uncertainties. Cold-air advection events generate unstable boundary layers, deep turbulence, and efficient upward heat fluxes. In contrast, warm-air advection suppresses mixing, creating a stable 鈥渓id鈥� that traps heat within the upper ocean for weeks to months.
This stability shift also produces a reversal in the sign of SST鈥搕urbulent heat flux coupling: the ocean controls the atmosphere under unstable conditions, but the atmosphere dominates under stable conditions. Additionally, stability shapes the ocean skin temperature structure, with warm-skin periods reducing flux estimates by roughly 9%.
Together, these results highlight stability鈥攏ot wind speed or mean temperature鈥攁s the primary regulator of summer air鈥搒ea heat exchange in the Pacific Arctic, with implications for flux algorithms, satellite retrievals, and predictions of upper-ocean heat storage in a rapidly changing climate.
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