How can anomalous western North Pacific Subtropical High intensify in late summer?

Authors

  • Baoqiang Xiang,

    Corresponding author
    1. International Pacific Research Center, University of Hawaii at Manoa, Honolulu, Hawaii, USA
    • Corresponding author: B. Xiang, International Pacific Research Center, University of Hawaii at Manoa, Honolulu, HI 96822, USA. (baoqiang@hawaii.edu)

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  • Bin Wang,

    1. International Pacific Research Center, University of Hawaii at Manoa, Honolulu, Hawaii, USA
    2. Department of Meteorology, University of Hawaii at Manoa, Honolulu, Hawaii, USA
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  • Weidong Yu,

    1. Center for Ocean and Climate Research, First Institute of Oceanography, State Oceanic Administration, Qingdao, China
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  • Shibin Xu

    1. International Pacific Research Center, University of Hawaii at Manoa, Honolulu, Hawaii, USA
    2. Physical Oceanography Laboratory, Ocean University of China, Qingdao, China
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Abstract

[1] The western North Pacific (WNP) Subtropical High (WNPSH) is a controlling system for East Asian Summer monsoon and tropical storm activities, whereas what maintains the anomalous summertime WNPSH has been a long-standing riddle. Here we demonstrate that the local convection-wind-evaporation-SST (CWES) feedback relying on both mean flows and mean precipitation is key in maintaining the WNPSH, while the remote forcing from the development of the El Niño/Southern Oscillation is secondary. Strikingly, the majority of strong WNPSH cases exhibit anomalous intensification in late summer (August), which is dominantly determined by the seasonal march of the mean state. That is, enhanced mean precipitation associated with strong WNP monsoon trough in late summer makes atmospheric response much more sensitive to local SST forcing than early summer.

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