Sea level pressure minimum along the Kuroshio and its extension

Youichi Tanimoto, Tomohisa Kanenari, Hiroki Tokinaga, Shang Ping Xie

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

Atmospheric effects of sea surface temperature (SST) fronts along the Kuroshio and Kuroshio Extension (K-KE) are investigated by examining spatial characteristics of the climatological sea level pressure (SLP), surface winds and surface heat flux (Q) fields based on an in situ observation dataset. A hydrostatic effect of the SST front is observed during the northwesterly monsoon characterized by a westward-extending low-SLP wedge (trough) slightly south of the peak in Q along the K-KE. Ageostrophic surface westerlies crossing SLP isobars toward a trough center are found north of the low-SLP wedge apparently because of the eastward acceleration by the vertical mixing effect. This feature of the ageostrophic winds is less pronounced south of it, a north-south asymmetry arising as vertical mixing accelerates (decelerates) eastward ageostrophic winds north (south) of it. While the SLP trough near the SST front is found nearly year-round except for summer, its meridional location seasonally migrates probably due to the change in the mean surface flow. Regional atmospheric model experiments are conducted to examine the effect of the SST front on the overlying atmosphere. The observed features in winter are adequately simulated when high-resolution SST is prescribed as the boundary condition. The strong Q along the K-KE and resultant SLP trough and ageostrophic surface winds are absent when the SST boundary condition is smoothed in space to weaken the SST front. These results illustrate that the cross-frontal change inQis of great importance to leave the SST imprint on the overlying atmosphere via hydrostatic and vertical mixing adjustments.

Original languageEnglish
Pages (from-to)4419-4434
Number of pages16
JournalJournal of Climate
Volume24
Issue number16
DOIs
Publication statusPublished - Aug 1 2011
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

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