A new approach for tracking the trajectory of oceanic warm pool

During the past two decades, the western Pacific warm pool (WP) is of growing concern following the recognition of its significant role in global climate change and its strong association with El Nino-Southern Oscillation phenomena. A fundamental issue in WP related studies is to locate its centroid and track its trajectory. The method used by some previous researchers for estimating the WP position seems to oversimplify the problem to a purely geometric one. This, however, is found to be systematically biased in both zonal and meridional directions. A new scheme for determining the WP centroid, which takes into account the thermal structure of the surface water, is proposed, resulting in a significant improvement in precise tracking of the WP trajectory compared to previous results. The proposed scheme may also be applicable to the determination of centers or axes of other oceanic features such as eddies, fronts and currents.