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Regional MJO Modulation of Northwest Pacific Tropical Cyclones Driven by Multiple Transient Controls
Author(s) -
Fowler M. D.,
Pritchard M. S.
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl087148
Subject(s) - madden–julian oscillation , climatology , tropical cyclone , cyclogenesis , anomaly (physics) , environmental science , tropical cyclogenesis , typhoon , downscaling , geology , precipitation , meteorology , cyclone (programming language) , convection , geography , physics , computer science , condensed matter physics , field programmable gate array , computer hardware
The Madden–Julian Oscillation (MJO) is widely acknowledged for its ability to modulate Northwest Pacific tropical cyclones (TCs), but a complete understanding of the underlying mechanisms remains uncertain. Beyond established effects of the MJO's relative humidity envelope, other dynamical factors have recently been invoked via new genesis potential indices and high‐resolution modeling studies. Here we revisit the ability of the MJO to modulate West Pacific TCs through a quasi‐explicit cyclone downscaling strategy driven by composited observations, paired later with a genesis index to investigate regional drivers of modulation. We reveal two distinct spatial modes of TC modulation in which the MJO's dynamic and thermodynamic effects act in tandem to increase TCs. In the South China Sea, for instance, shear reductions associated with the MJO's circulation lead to increasing potential intensity ahead of the arrival of a positive humidity anomaly, all of which combine for an extended period of cyclogenesis favorability.