Anticyclonic Suppression of the North Pacific Transient Eddy Activity in Midwinter

Abstract Dynamical understandings of midlatitude transient eddy activity, especially its midwinter minimum over the North Pacific, are still limited, partly because conventional Eulerian eddy statistics are incapable of separating cyclonic and anticyclonic contributions. Here we evaluate the two con...

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Main Authors: Satoru Okajima, Hisashi Nakamura, Yohai Kaspi
Format: Article
Language:English
Published: Wiley 2024-01-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2023GL106932
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author Satoru Okajima
Hisashi Nakamura
Yohai Kaspi
author_facet Satoru Okajima
Hisashi Nakamura
Yohai Kaspi
author_sort Satoru Okajima
collection DOAJ
description Abstract Dynamical understandings of midlatitude transient eddy activity, especially its midwinter minimum over the North Pacific, are still limited, partly because conventional Eulerian eddy statistics are incapable of separating cyclonic and anticyclonic contributions. Here we evaluate the two contributions separately based on local curvature of instantaneous flow fields to compare their seasonality between the North Pacific and North Atlantic storm‐tracks. The anticyclonic contribution is found crucial for the midwinter minimum of the North Pacific transient eddy activity. Eddy energetics reveals that the net efficiency of the anticyclonic contribution in replenishing total transient eddy energy over the North Pacific exhibits a pronounced midwinter minimum leading to net energy loss, while that of its cyclonic counterpart does not, in harmony with a precipitation peak around midwinter. This study suggests that more attention should be paid to anticyclones in studying midlatitude storm‐track dynamics.
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spelling doaj-art-0c0fcd7db9124e799ea3c1737aa004392025-08-20T02:11:09ZengWileyGeophysical Research Letters0094-82761944-80072024-01-01512n/an/a10.1029/2023GL106932Anticyclonic Suppression of the North Pacific Transient Eddy Activity in MidwinterSatoru Okajima0Hisashi Nakamura1Yohai Kaspi2Research Center for Advanced Science and Technology The University of Tokyo Tokyo JapanResearch Center for Advanced Science and Technology The University of Tokyo Tokyo JapanDepartment of Earth and Planetary Sciences Weizmann Institute of Science Rehovot IsraelAbstract Dynamical understandings of midlatitude transient eddy activity, especially its midwinter minimum over the North Pacific, are still limited, partly because conventional Eulerian eddy statistics are incapable of separating cyclonic and anticyclonic contributions. Here we evaluate the two contributions separately based on local curvature of instantaneous flow fields to compare their seasonality between the North Pacific and North Atlantic storm‐tracks. The anticyclonic contribution is found crucial for the midwinter minimum of the North Pacific transient eddy activity. Eddy energetics reveals that the net efficiency of the anticyclonic contribution in replenishing total transient eddy energy over the North Pacific exhibits a pronounced midwinter minimum leading to net energy loss, while that of its cyclonic counterpart does not, in harmony with a precipitation peak around midwinter. This study suggests that more attention should be paid to anticyclones in studying midlatitude storm‐track dynamics.https://doi.org/10.1029/2023GL106932storm trackenergeticsanticyclonemidwinter minimumcurvaturecyclone
spellingShingle Satoru Okajima
Hisashi Nakamura
Yohai Kaspi
Anticyclonic Suppression of the North Pacific Transient Eddy Activity in Midwinter
Geophysical Research Letters
storm track
energetics
anticyclone
midwinter minimum
curvature
cyclone
title Anticyclonic Suppression of the North Pacific Transient Eddy Activity in Midwinter
title_full Anticyclonic Suppression of the North Pacific Transient Eddy Activity in Midwinter
title_fullStr Anticyclonic Suppression of the North Pacific Transient Eddy Activity in Midwinter
title_full_unstemmed Anticyclonic Suppression of the North Pacific Transient Eddy Activity in Midwinter
title_short Anticyclonic Suppression of the North Pacific Transient Eddy Activity in Midwinter
title_sort anticyclonic suppression of the north pacific transient eddy activity in midwinter
topic storm track
energetics
anticyclone
midwinter minimum
curvature
cyclone
url https://doi.org/10.1029/2023GL106932
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AT hisashinakamura anticyclonicsuppressionofthenorthpacifictransienteddyactivityinmidwinter
AT yohaikaspi anticyclonicsuppressionofthenorthpacifictransienteddyactivityinmidwinter