US-GLOBEC NEP Phase IIIa-CCS: Coupled physical-biological dynamics in the Northern California Current System: A Synthesis of Seasonal and Interannual Mesoscale Variability and its Links to Regional Climate Change
T. Cowles, J. Barth, R. Letelier, Y. Spitz [All at Oregon State University], M. Zhou [Boston University]

Project Summary

We will evaluate the link between mesoscale physical dynamics, as driven by local and remote forcing, and the variability in phytoplankton and zooplankton abundance and spatial pattern observed across the Global Ocean Ecosystem Dynamics (GLOBEC) Northeast Pacific domain. The ecological response to mesoscale physical dynamics is not limited to a mesoscale spatial domain, but, as stated within the GLOBEC program goals, an understanding of the linkage to ecological dynamics over larger spatial scales and longer time scales is critically dependent upon a characterization of the mesoscale physical/biological interactions. A test of that understanding rests on our ability to extend the mesoscale observations (and ecological response) beyond the spatial and temporal boundaries of our study area, through the use of satellite data, coupled physical/biological models as well as comparisons with datasets having coarser spatial resolution but extending across longer time scales than our specific observations, such as the GLOBEC Long Term Observation Program , mooring, and satellite remote sensing time series. Therefore, we will use physical and biological mesoscale observations obtained in the northern California Current system between 1999 and 2002 to address specific goals within the GLOBEC programmatic framework. Our two primary objectives are to

• determine the contribution of variability in mesoscale physical forcing and ocean dynamics to the variability in ecosystem dynamics, as expressed by phytoplankton and zooplankton abundance, spatial pattern, size distribution and indices of production;
• extend this mesoscale understanding across a larger spatial domain and across longer time scales through the use of coupled models and other GLOBEC datasets.

These overall objectives will be addressed through a set of linked, interdisciplinary analyses to be conducted over the next three years that address spatial pattern, ecosystem response, and mesoscale to regional linkages. Within each of these topic areas we will examine the consequences of variability in forcing on the ecosystem. A major goal of our project is to develop "indices" of mesoscale variability in both the physical and biological properties of the northern California Current and to relate those indices to changes in energy input into the system, e.g. interannual changes in wind forcing. We will approach the three topic areas: Spatial Pattern, Ecosystem Function, and Mesoscale to Regional Linkages, by pursuing the following objectives. We will

Spatial:

• quantify the variability in mesoscale spatial patterns of phytoplankton populations using the bio-optical data obtained from SeaSoar sections and underway surface data, in the context of the variability in physical forcing;
• quantify the variability in mesoscale spatial patterns of zooplankton populations using the bio-acoustical data obtained from the towed HTI system and the Optical Plankton Counter data obtained from SeaSoar sections, in the context of the variability in physical forcing;

Ecosystem Function:

• evaluate the role of the position, strength and intensity of the upwelling front (and coastal jet) in defining mesoscale indices of plankton biomass and productivity;
• investigate the consequences of variable physical dynamics on the variability in the size structure and composition of the phytoplankton and zooplankton assemblages, using pigment data, flow cytometry samples, and bio-optical indices for phytoplankton. We will use direct measures of zooplankton size from zooplankton collections and indirect measures from the OPC and inversions of acoustic spectra from the HTI.
• collaborate with the core GLOBEC modeling team (Haidvogel et al.) to evaluate numerical solutions in the context of our mesoscale analyses;
• test hypotheses about bio-physical interactions by examining a range of ecosystem modeling scenarios that will be coupled to the Haidvogel et al. circulation model;

Mesoscale to Regional:
quantify the seasonal and interannual temporal variability of physical forcing and the dynamical physical and biological response within the mesoscale domain

Broader Impact - We will disseminate the results of this synthesis of interdisciplinary datasets through multi-authored papers, linked websites, and through LiveAccess servers. Our results regarding biophysical dynamics in the northern California Current System should be applicable to other eastern boundary current regions with wind-driven variability. We also will extend the impact of this synthesis, and address the broader impacts of this work, through collaboration with the Oregon Office of Adult Education. Investigators will work directly with adult education instructors in Oregon through classroom visits and staff development workshops. The OSU collaboration with the Oregon Office of Adult Education began earlier this past year, and the Director of Adult Education already has in place the organizational structure to distribute across the state any new ocean science materials that result from this project, thus maximizing the exposure of ocean sciences teaching material to thousands of adult students in Oregon.

NSF Award Summary

Ecological responses to mesoscale physical dynamics are not limited to a mesoscale spatial domain. Consequently, an understanding of the linkage to ecological dynamics over larger spatial scales and longer time scales is critically dependent upon a characterization of the mesoscale physical/biological interactions. The investigators propose to evaluate the link between mesoscale physical dynamics, as driven by local and remote forcing, and the variability in phytoplankton and zooplankton abundance and spatial pattern observed across the GLOBEC Northeast Pacific region. The two primary objectives are to (1) determine the contribution of variability in mesoscale physical forcing and ocean dynamics to the variability in ecosystem dynamics, as expressed by phytoplankton and zooplankton abundance, spatial pattern, size distribution and indices of production and (2) extend this mesoscale understanding across a larger spatial domain and across longer time scales through the use of coupled models and other GLOBEC datasets. The investigators will examine the consequences of variability in forcing on the ecosystem and develop indices of mesoscale variability in both the physical and biological properties of the northern California Current. The indices will be related to changes in energy input into the system, e.g. interannual changes in wind forcing. Within the GLOBEC synthesis effort, this work will contribute to a causal understanding of the link between local physical and biological mesoscale activity to large spatial-scale, long time-scale regional forcing, and will establish a basis for developing a predictive capability for estimating mesoscale ecosystem response to forcing. The results will be disseminated through multi-authored papers, linked websites, and through LiveAccess servers. The investigators also propose to collaborate with the Oregon Office of Adult Education.

This page was last updated on March 14, 2007.

Maintained by:
Hal Batchelder
College of Oceanic and Atmospheric Sciences
Oregon State University
Corvallis, OR 97331-5503
phone: 541-737-4500; FAX 541-737-2064