Upper Ocean Dynamics and Air-Sea Interaction drivers of the North Pacific Decadal Variability
Event: 2014 Ocean Surface Topography Science Team Meeting
Session: Science Results from Satellite Altimetry: Regional and basin-scale processes and sea level rise
Presentation type: Type Poster
The prominent decadal climate mode often called the Pacific Decal Oscillation (PDO) is an inter-decadal sea surface temperature (SST) variability pattern in the North Pacific. The PDO is understood to have links to climate variability in North America, and impacts on water resources in the western U.S. and Canada. The PDO variability evident from satellite altimetry is a sea surface height (SSH) mode that is highly coherent with SST, both spatially and temporally. The consistency between the SSH and SST PDO variability indicates a coherent oceanic response to both diabatic heating and momentum fluxes from the atmosphere. Here we superimpose one-dimensional models to estimate thermal and SSH over the 22 year altimeter record. One is the General Ocean Turbulence Model (GOTM), used to simulate the vertical thermal structure of the upper ocean based on diabatic heating and mixing parameterizations. The other is a simple dynamic model of vertical pycnocline motion that is driven by Ekman pumping and moderated by a damping term that is used to simulate SSH as an indicator of pycnocline depth. Lastly, we examine the cumulative effect of varying horizontal heat advection and convergence associated with surface circulation and horizontal temperature gradients. Each simulation approach recovers salient features of the principal SSH EOF pattern that characterizes the PDO variability. An analysis to optimize superimposing these approaches, and their relative significance, is in progress and results will be presented.