Research on the response of the upper layer heat structure in the Western Pacific Warm Pool to the mean Madden-Julian Oscillation

Abstract

By using the long-term observed hydro-meteorological data (1985–2002) from the Tropical Atmosphere Ocean System (TAO) during the international Tropical Ocean and Global Atmosphere (TOGA) experiment, the key parameters of the Sea Surface Temperature (SST), thermocline depth, surface sensible heat flux and latent heat flux, and the pseudo wind stress in the Westen Equatorial Ocean are calculated in this paper. On the basis of the calculation, the response of upper layer heat structure in the Westen Pacific Warm Pool to the mean Madden-Julian Oscillation (MJO) and its relation to the El Nino events are analyzed. The results show that within the MJO frequency band (42–108d), the distributions of sea surface wind stress and upper ocean temperature have several spatial-temporal variation structures. Among these structures, the type-I surface pseudo wind stress field plays the role of inhibiting the eastward transport of ocean heat capacity, while the type-II strengthens the heat capacity spreading eastward. Therefore the type-II surface pseudo wind stress field is the characteristic wind field that provokes El Nino events. During calm periods (July–September) of the wind stress variations, the sensible and latent heat capacity fluxes change considerably, mostly in the region between 137°–140°E, while to the east of 150°E, the heat capacity flux changes less.