Different Influences of Two El Niño Types on Low-Level Atmospheric Circulation over the Subtropical Western North Pacific.

This study focuses on different evolutions of the low-level atmospheric circulations between eastern Pacific (EP) El Niño and central Pacific-II (CP-II) El Niño. The western North Pacific anomalous anticyclone (WNPAC) originates from the northern South China Sea for EP El Niño, and moves to the western North Pacific (WNP) afterward. Compared with EP El Niño, the origin of theWNPAC is farther west during CP-II El Niño,with the center over the Indochina Peninsula.Moreover, theWNPACshows aweaker eastward shift. Such discrepancies are attributed to different evolutions of the cyclonic response over theWNP, which can suppress the convection in the western flank of the anomalous cyclone. The eastward retreat of the anomalous cyclone is significant for EP ElNiño, but less evident for CP-II El Niño. These discrepancies are related to zonal evolutions of the increased precipitation over the equatorial Pacific. Following the southwardmigration of the intertropical convergence zone (ITCZ), the deep-convection region extends eastward along the equator, reinforcing the atmospheric response to the eastern Pacificwarming inEPElNiño. ForCP-II ElNiño, the atmospheric response is insignificant over the eastern Pacific without warming. Moreover, the meridional migration of the ITCZ can modulate zonal variations of the easterly tradewind and specific humidity aswell.Due to the combined effects of the climatological background and atmospheric anomalies, the specific humidity--induced and wind-induced moist enthalpy advection contribute to different shifts of the precipitation center. [ABSTRACT FROM AUTHOR]