SIO'S PARTICIPATION IN US GODAE: SUSTAINED GLOBAL OCEAN STATE ESTIMATION FOR SCIENTIFIC AND PRACTICAL APPLICATION

Dean Roemmich, Bruce Cornuelle and Russ Davis (SIO)

Link to NOAA Strategic Plan: NOAA's Mission Goal 2: Understand Climate Variability and Change to Enhance Society's Ability to Plan and Respond

RESEARCH OBJECTIVES AND SPECIFIC PLANS TO ACHIEVE THEM

The SIO role in GODAE provides the direct linkage between Argo and other in situ ocean observational elements with the modeling and assimilation elements of the ECCO-GODAE consortium. The use of Argo float profiles is a major GODAE activity. As with any new dataset there are many issues to be confronted for successful use of the data, and the SIO responsibility is to provide the required knowledge of datasets and expertise with instrumentation. The SIO group also serves as an interface between assimilation activities and CLIVAR science. The ocean research carried out under CLIVAR involves three types of work with ocean data: (a) improvement in seasonal-interannual climate forecasting, including investigation of initialization of the ocean in forecast models, (b) interpretation of field process experiments focused on improving the representation in models of ocean processes, and (c) analyses of observed climate variability with an ocean focus on individual basins. Our goal is to use ocean state estimates (or ocean re-analyses) to explore the dynamical processes behind the observed variability.

RESEARCH ACCOMPLISHMENTS

Ph.D. student Elizabeth Douglass has nearly completed her dissertation, including data analysis and ocean data assimilation (ODA) using the ECCO model to study interannual variability in ocean circulation and heat and freshwater transport in the North Pacific Ocean. The results indicate as strong role for subsurface datasets in ODA modeling. The subsurface ocean is not adequately represented in the model unless constrained by subsurface data with appropriate weighting. Northward ocean heat transport during the 1990s had substantial interannual variability, amounting to about 50% of the mean. A strong maximum in northward heat transport in 1998 coincided with a minimum in air-sea heat exchange and therefore a maximum in heat storage.

D. Roemmich and colleagues described a spin-up of the deep South Pacific gyre circulation by some 20-30% as seen in data from WOCE, Argo, and satellite altimetry. The spin-up signal has been duplicated in simple wind-driven models, as a response to enhanced wind-stress curl on decadal time-scales. A challenge for ODA models is to describe the global forcing and response of this Southern Ocean signal, which is the most prominent feature of decadal variability in sea surface height seen by satellite altimetry.

Specialist J. Gilson continues to improve techniques for delayed-mode quality control of Argo data, and he participates in international efforts aimed at standardizing and optimizing the Argo dataset. Gilson’s graphical user interface for Argo quality control has been widely adopted by international Argo. This work has great benefits for GODAE because it will provide a self-consistent and high quality Argo dataset suitable for GODAE.