Subsurface Ocean dynamics during two flavors of El Nino

Abstract:

This study focuses on ocean subsurface temperature and its dynamics during two types of El Nino events, CP and EP. For the last 10-15 years, CP El Nino has been more frequently observed than EP El Nino. The atmospheric dynamics and different effects of the two types of El Nino on local climate have been extensively studied while the corresponding ocean dynamics under the sea surface have been less explored. Using SODA 2.2.4 dataset, we investigate how the subsurface water temperature is differentiated during two types of El Nino, especially focusing on onset and termination of the El Nino. We found that CP and EP El Nino have different origins of subsurface warm water over western Pacific Ocean. And we also show that subsurface cold water along the equator plays a role in terminating the both types of El Nino. The relationship between the subsurface water and wind stress curl is investigated to see whether the ocean-atmospheric teleconnections have different dynamics during CP and EP El Nino. This study will provide better understanding on the CP and EP El Nino dynamics especially under the sea surface and the subsurface dynamics can be exploited as one of the predictors of the El Nino events.