Summertime atmosphere–ocean preconditionings for the Bering Sea ice retreat and the following severe winters in North America

Atmospheric responses to sea ice retreat in the Bering Sea have been linked to recent extreme winters in North America. We investigate the leading factor for the interannual variability of Bering sea ice area (SIA) in early winter (November–December), using canonical correlation analysis based on se...

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Bibliographic Details
Published in:Environmental Research Letters
Main Authors: Takuya Nakanowatari, Jun Inoue, Kazutoshi Sato, Takashi Kikuchi
Format: Article in Journal/Newspaper
Language:English
Published: IOP Publishing 2015
Subjects:
sea ice
Bering Sea
ocean/atmosphere interactions
climate change and variability
tropical convection
ocean predictability and prediction
Environmental technology. Sanitary engineering
TD1-1066
Environmental sciences
GE1-350
Science
Q
Physics
QC1-999
Gulf of Alaska
Pacific
Sea ice
Alaska
Online Access:https://doi.org/10.1088/1748-9326/10/9/094023
https://doaj.org/article/a9d67adf125e4635970f425f90e583e4
Description
Summary:Atmospheric responses to sea ice retreat in the Bering Sea have been linked to recent extreme winters in North America. We investigate the leading factor for the interannual variability of Bering sea ice area (SIA) in early winter (November–December), using canonical correlation analysis based on seasonally resolved atmosphere and ocean data for 1980–2014. We found that the 3-month leading (August–September) geopotential height at 500 hPa (Z500) in the Northern Hemisphere explains 29% of SIA variability. The spatial pattern of Z500 for positive (negative) sea ice anomalies is associated with negative (positive) anomalies over the Gulf of Alaska related to the Pacific transition (PT) pattern. The heat budget analysis indicates that summertime atmospheric conditions influence SIA through the ocean temperature anomalies of the Alaskan Coastal Current forced by atmospheric turbulent heat fluxes. The PT pattern highly correlates with convective precipitation in the western subtropical Pacific, implying that weakened subtropical forcing is the likely cause for the recent extreme winters in North America. Our results present a major factor for interannual variability in the Bering SIA, and further would contribute to the improvement of forecasting winter climate in North America.

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