Intensification of the subpolar front in the Sea of Japan during winter cyclones

Ning Zhao, Shinsuke Iwasaki, Atsuhiko Isobe, Ren Chieh Lien, Bin Wang

    Research output: Contribution to journalArticlepeer-review

    2 Citations (Scopus)

    Abstract

    The response of the subpolar front in the Sea of Japan (also known as the East Sea) to winter cyclones is investigated based on quantitative analyses of gridded and satellite data sets. Cyclone passages affecting the sea are detected using time series of spatially averaged surface turbulent heat fluxes. As the cyclones develop, there are strong cold-air outbreaks that produce twice the normal heat loss over the sea. After removal of sea surface temperature (SST) seasonal trends, we found that cyclone passage (hence, cooling) mainly occurred over 3 days, with maximum SST reduction of -0.4°C. The greatest reduction was found along the subpolar front, where frontal sharpness (i.e., SST gradient) increased by 0.1°C (100 km)-1. Results of a mixed-layer model were consistent with both temperature and frontal sharpness, and localized surface cooling along the subpolar front resulted from both horizontal heat advection and turbulent heat fluxes at the sea surface. Further analyses show that this localized cooling from horizontal heat advection is caused by the cross-frontal Ekman flow (vertically averaged over the mixed layer) and strong northwesterly winds associated with the cold-air outbreak during cyclone passage.

    Original languageEnglish
    Pages (from-to)2253-2267
    Number of pages15
    JournalJournal of Geophysical Research: Oceans
    Volume121
    Issue number4
    DOIs
    Publication statusPublished - Apr 1 2016

    All Science Journal Classification (ASJC) codes

    • Geochemistry and Petrology
    • Geophysics
    • Earth and Planetary Sciences (miscellaneous)
    • Space and Planetary Science
    • Oceanography

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