Friedrichs¹, Marjorie A. M., Jerry D. Wiggert², Raleigh R. Hood³, Ragu Murtugudde², Julian P. McCreary⁴, Robert A. Armstrong⁵, Fei Chai⁶, James Christian⁷, John Dunne⁸, Scott Doney⁹, Katja Fennel¹⁰, Eileen E. Hofmann¹, John M. Klinck¹, Dennis J. McGillicuddy⁹, J. Keith Moore¹¹, Yvette Spitz¹², Kevin Arrigo¹³ and David M. Glover⁹

¹Center for Coastal Physical Oceanography, Old Dominion University, Norfolk, VA 23529, Tel: 757-683-5560, Fax: 757-683-5550, E-mail: marjy@ccpo.odu.edu, ²ESSIC, University of Maryland, College Park, MD 20742, ³University of Maryland Center for Environmental Science, Cambridge, MD 21613, ⁴International Pacific Research Center, University of Hawaii, Honolulu, HI 96822, ⁵Marine Sciences Research Center, SUNY, Stony Brook, NY 11794, ⁶School of Marine Sciences, University of Maine, Orono, ME 04469, ⁸Princeton University, AOS Program, Princeton, NJ 08544, ⁹Woods Hole Oceanographic Institution, Woods Hole, MA 02543, ¹⁰Rutgers, The State University of New Jersey, IMCS, New Brunswick, NJ 08901, ¹¹Earth System Science, University of California, Irvine, Irvine, CA 92697, ¹²COAS, Oregon State University, Corvallis, OR 97331, ¹³Stanford University, Department of Geophysics, Stanford, CA 94305

The Regional Ecosystem Modeling Testbed Project

An important legacy of the U.S. JGOFS Synthesis and Modeling Project will be the formulation of a broad suite of models designed to simulate biogeochemical cycling in the various process study regions. Although these modeling studies have already substantially advanced our understanding of these systems, few quantitative intercomparisons of these models have been made. As part of the Regional Ecosystem Modeling Testbed Project we are conducting these intercomparisons, in order to critically examine which ecosystem structures and formulations are most robust, and explore the reasons for their success. In order to facilitate these intercomparisons we are developing a set of regional testbeds, containing one-dimensional physical forcing fields and biogeochemical data. By running various ecosystem models using the same physical forcing, and evaluating them using the same data, we objectively compare different ecosystem models and modeling approaches.

Work to date has focused on two regions: the equatorial Pacific (140W) and the Arabian Sea (15.5N, 61.5E); plans for other regions including the Southern Ocean, BATS, and HOT are currently underway. A prototype testbed in the Arabian Sea has been used to compare assimilative versions of three distinct ecosystem models. Results highlight the importance of the physical forcing fields (vertical velocity and mixed layer depth) and suggest that the additional complexity of multiple size class models may not always be justified. A Regional Testbed Workshop (March 2003) provided a venue for JGOFS investigators to use these testbeds to compare ecosystem model simulations. Results from this ecosystem model comparison will be presented.