The El Niño—Southern Oscillation and sea surface temperatures around the Maritime Continent

In their canonical paper describing the development of El Niño – Southern Oscillation (ENSO) episodes (Rasmusson and Carpenter, 1982), the authors document the sea surface temperature anomalies associated with different stages of the development of an El Niño episode. Although most attention focuses on the central and eastern equatorial Pacific, interesting sea surface temperature anomalies also appear in the west Pacific and especially around the Maritime Continent (Indonesia, new Guinea, northern Australia). During August-October, during the development of a major El Niño, sea surface temperatures tend to be cooler than usual around the Maritime Continent. But there is an abrupt change to warmer than usual temperatures in this region in December-February. By this season, at the peak of the El Niño episode, the ocean surface across most of the global tropics is warmer than usual. Nicholls (1984) further documented the seasonally varying changes in sea surface temperature anomalies around the Maritime Continent during the development and end of an El Niño episode. Rapid changes in the sign of Maritime Continent sea surface temperature anomalies tended to lead changes in east equatorial Pacific temperatures, especially at the end of an El Niño event. Catto et al (2012a, b) demonstrated that these seasonally varying links between Maritime Continent sea surface temperatures and eastern equatorial Pacific temperatures during El Niño episodes had continued to occur in the 30 years subsequent to the Rasmusson/Carpenter and Nicholls papers. Catto et al also demonstrated that at least some coupled ocean-atmosphere climate models could reproduce the seasonally varying links. Nicholls (1984) proposed that air-sea interactions around the Maritime Continent could explain the seasonally varying links. In this paper I will re-examine the links between the Maritime Continent and the El Niño – Southern Oscillation, focussing on how consistent they have been through the past three decades, discuss how well models reproduce these links, and consider whether the links can be understood within the current ENSO paradigm.

Catto, J., Nicholls, N, and Jakob, C., 2012a. North Australian sea surface temperatures and the El Niño Southern Oscillation in observations and models, J. Climate, 25, 5011-5029, doi:10.1175/JCLI-D-11-00311.1.

Catto, J., Nicholls, N., and Jakob, C., 2012b. North Australian sea surface temperatures and the El Nino Southern Oscillation in the CMIP5 models. J. Climate, 25, 6375-6382, doi:10.1175/JCLI-D-12-00214.1

Nicholls, N. 1984. The Southern Oscillation and Indonesian sea-surface-temperature. Mon. Weath. Rev., 112, 424-432.

Rasmusson, EM and Carpenter, TH, 1982. Variations in Tropical Sea Surface Temperature and Surface Wind Fields Associated with the Southern Oscillation/El Niño, Monthly Weather Review, 110, 354-384.