Influences of boreal summer intraseasonal oscillation on heat waves in monsoon asia

Pang Chi Hsu, June Yi Lee, Kyung Ja Ha, Chih Hua Tsou

研究成果: 雜誌貢獻文章同行評審

28 引文 斯高帕斯(Scopus)

摘要

By analyzing observation-based high-resolution surface air temperature (SAT) data over the Asian monsoon region (here called "monsoon Asia") for 1981-2007, the modulation by boreal summer intraseasonal oscillation (BSISO) of heat wave (HW) occurrence is examined. Strong SAT variability and a high probability of HW occurrence on intraseasonal time scales are found consistently in the densely populated regions over central India (CI), the YangtzeRiver valley in China (YR), Japan (JP), and theKorean Peninsula (KP). The two distinct BSISO modes (30-60-day BSISO1 and 10-30-day BSISO2) show different contributions to HW occurrence in monsoon Asia. A significant increase inHWoccurrence over CI (YR) is observed during phases 2-3 (8-1) of BSISO2 when the 10-30-day anticyclonic and descending anomaly induce enhanced upward thermal heating and sensible heat flux (warm advection) around the areas. On the other hand, the northeastward propagating BSISO1 is closely connected to the increased HW probability over JP and KP. During phases 7-8 of BSISO1, the 30-60-day subsidence along with the low-level anticyclonic anomaly moves into northeastern Asia, leading to enhanced diabatic (adiabatic) warming near surface in JP (KP). Analysis of a three-dimensional streamfunction tendency equation indicates that diabatic cooling induced by the BSISO-related suppressed convections is the main forcing term of anticyclonic anomaly although it is largely offset by the decreased static stability associated with adiabatic warming. The BSISO-related vorticity advection leads to an anticyclonic (cyclonic) tendency to the northwestern (southeastern) part of the center of anticyclonic anomaly, favoring northwestward development of the BSISO anomalous circulations and thus providing a favorable condition forHWoccurrence over the western Pacific-EastAsia sector.

原文英語
頁(從 - 到)7191-7211
頁數21
期刊Journal of Climate
30
發行號18
DOIs
出版狀態已發佈 - 2017 九月 1

ASJC Scopus subject areas

  • Atmospheric Science

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