Collaborative Research: Decadal Coupled Ocean-Atmosphere Interactions in the North Pacific

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OCE-0647815Recent work reveals that anomalies of wintertime Sea Surface Temperatures (SST) in a large area surrounding the Kuroshio-Oyashio Extension (KOE) in the northwest Pacific are predictable from the history of wind stress over North Pacific. This predictable component of SST is of interest for North Pacific climate because the KOE is a region of vigorous air-sea interaction, which is linked to large-scale North Pacific/North American atmospheric climate variability. Important gaps remain in our understanding of the mechanisms involved in the climate variations associated with the KOE region. These gaps include the ways that the atmosphere may respond to the predictable changes in the KOE SST; the detailed nature of the atmospheric tropospheric response across the North Pacific/North American sector; the means by which planetary waves, carrying the predictable signal in the North Pacific, change SST, mesoscale eddies, horizontal velocity and upwelling in the North Pacific; and the importance of mesoscale ocean variations, which create associated surface wind stress and heat flux anomalies, in establishing climate-scale KOE SST anomalies. Intellectual Merit: This project aims to clarify these issues by downscaling the National Center for Environmental Prediction (NCEP) reanalysis fields of the past 50 years over the North Pacific using a high-resolution regional coupled ocean atmosphere model (SCOAR) that includes mesoscale eddies. With an ensemble of these coupled downscaling experiments, combined with a related combination of uncoupled ocean and uncoupled atmospheric model hindcasts, the results will be diagnosed and validated with observations to estimate the fraction of variance associated with regional ocean-atmosphere feedbacks in the context of decadal feedback loops and climate predictability. The analysis will focus on the complicated sequence of processes that link regional ocean circulation and SST anomalies in the KOE region to the atmospheric boundary layer and the storm track with the basin-scale processes that govern the excitation and propagation of thermocline perturbations from the central North Pacific, which modulate the circulation and SST in the KOE region. Broader Impacts: The results of this research project may have important practical use in improving atmospheric climate forecasting on inter-annual timescales in the North Pacific (and downstream over North America). The predictable component of SST (and the associated upper-ocean temperature, velocity and upwelling fields) is also of interest because the region has commercially important fisheries that are linked to ecosystem changes driven by this variability of the KOE region. The results from this project may be useful for creating novel forecasts of the ecosystem (including fisheries) in the KOE region of the North Pacific. Understanding the physics of the coupled ocean-atmosphere response in the KOE region and its role in forcing the basin-scale atmospheric is paramount in attempting to exploit the relationships between decadal variability and its downstream effects on climate of North America, the ecosystem and fisheries (including those of the Gulf of Alaska, Bering Sea and California Current).This project is a contribution to the U.S. CLIVAR (CLImate VARiability and predictability) program.