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- Title
Autumnal Equinox Shift in Arctic Surface Energy Budget: Beaufort‐Chukchi Seas Case Study.
- Authors
Carrigg, Joseph; Yu, Lisan; Menezes, Viviane V.; Chen, Yanxu
- Abstract
This study examines the annual cycle of the Surface Energy Budget (SEB) in the Beaufort‐Chukchi seas, focusing on the autumn transition. Shipboard measurements from NASA's Salinity and Stratification at the Sea Ice Edge (SASSIE) experiment (8 September–2 October 2022) and satellite flux analysis for the entire 2022 were utilized to provide a comprehensive perspective of the SEB's seasonal dynamics. An important finding is the alignment of SEB's autumnal transition with the September 22 equinox, marking the onset of prolonged Arctic darkness. This transition involved a shift from the summertime radiative heating to cooling conditions, characterized by outgoing longwave radiation surpassing incoming solar radiation and a notable increase in synoptic turbulent latent and sensible heat flux variability. The increased turbulent heat fluxes after the equinox were associated with increased occurrences of short‐duration cold air outbreaks. These outbreaks seem to originate from cold mesoscale surface winds transitioning from cooling landmasses or ice caps to the warmer seas, driven by differential cooling rates between land/ice and ocean as solar irradiance declined. Turbulent heat losses, outpacing longwave emission by more than fivefold, accelerated ocean surface cooling in the subsequent 2 months, leading to the complete freeze‐up of the Beaufort‐Chukchi seas by late November. These findings underscore the substantial influence of astronomical seasons on the SEB, emphasizing their crucial role in Arctic climate dynamics. Plain Language Summary: This study is to enhance understanding of Arctic Surface Energy Budget (SEB) patterns, focusing on energy exchanges at the open sea surface over the year. It examines autumn energy transition in the Beaufort‐Chukchi seas, using shipboard measurements from NASA's SASSIE experiment (8 September–2 October 2022) and satellite heat flux analyses for the entire year of 2022. These data sources offer insights into the energy flows and patterns in the region. An important finding is the alignment of the autumn energy transition with the September 22 equinox, marking the onset of the extended Arctic darkness and the transition from oceanic heat gain to loss. Cold air outbreaks from surrounding landmasses and ice caps increased, intensifying heat transfer from the ocean to the atmosphere through evaporation, conduction, and convection. Turbulent heat loss exceeded longwave emission by over fivefold, expediting ocean surface cooling over the subsequent 2 months, culminating in complete freezing of the Beaufort‐Chukchi seas by late November. Understanding the influence of astronomical seasons on the SEB is crucial for comprehending and predicting the Arctic climate changes. Key Points: Autumnal Equinox pivotal in ocean surface energy budget: heat loss began to surpass solar radiation gain per shipboard and satellite dataPost‐equinox, synoptic turbulent heat flux variability surged, linked to frequent cold, dry air outbreaks with a duration of a few daysTurbulent heat fluxes, five times longwave emission, accelerated ocean heat release, causing the Beaufort‐Chukchi seas freeze in November
- Subjects
UNITED States. National Aeronautics &; Space Administration; ENERGY budget (Geophysics); AUTUMNAL equinox; HEAT losses; HALOCLINE; HEAT flux; SEA ice
- Publication
Journal of Geophysical Research. Oceans, 2024, Vol 129, Issue 5, p1
- ISSN
2169-9275
- Publication type
Article
- DOI
10.1029/2023JC020788