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Real-Time Data Assimilation on Georges Bank

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Final Summary Report CICOR Cooperative Agreement 1998-2002

Dennis J. McGillicuddy, Jr.
Department of Applied Ocean Physics & Engineering
Woods Hole, MA 02543

Cabell S. Davis, III
Biology Department
Woods Hole, MA 02543

Program Manager ; Dr. Beth Turner, NOAA Coastal Ocean Program

As part of the third phase of the U. S. Globec Georges Bank Program, a group of investicators from six institutions (Dartmouth College, WHOI, NMFS, UNC-CH , BNL and BIO undertook a predictive modeling effort in conjunction with field activities during several cruises from April to June 1999. Results from process studies of cross-frontal exchange on R/V Endeavor cruises EN323, EN324 and EL9905 are reported in Lynch et al. (2001).

The principal objective was simultaneous assessment of the transport of water and plankton in the vicinity of the tidal mixing front. The approach was to inject Rhodamine dye into specific density strata and then measure the movement of the dye patch and the associated lanktonic community with respect to the neighboring front. This was accomplished through incorporation of fluorofmetrlc dye detector into the Video Planktong Recorder system, facilitating real-time assessment of both tracer and plankton distributions (down to the species level). The adjacent waters were also seeded with radio - and satellite-tracked drifters. Real-time data assimilative modeling of the flow field (and associated transports of tracer and plankton) was carried out in concert with the observational activities, in order to (1) provide an additional interpretive framework for the measurements, and (2) provide nowcast/forecast products which could be used in planning sampling strategy.

Skill of the model predictions was evaluated against observed drifter trajectogries. In aggregate, the error growth characteristics of the ensamble of "best" model forecasts were suprisingly uniform. For the four-day time horizon over which forecast skill was evaluated in the various experiments, forecast error was a linear function of the duration of the prediction. On average sparation between simaulaterd and observed trajectories of drifters and dye grew at a rate of 3  km/day. This error growth rate is small given the physical context of order 100 cm /sec tides and 10-30 cm/sec residual flows in this region.

While at sea, model solutions were used as a basis for data-assimilative coupled physical/biological simulations. Observed distbutions of Calanus finmarchicus and hydroid predators were assimulated into the modeled flow fields in order to asses ther relatvie transports and interactions (Figure 1; also see animation at cal.fli.

Coupled simulations revealed portions of overlap in the sampling coverage due to the configuration of the survey track and phasing with the tide. Relative motion between predator and prey was apparent due to the vertical separation of the two populations in the presence of shear.

References and talks:
Lynch, D.R, Naimie, C.E., Ip, J.T., Lewis, C.V., Werner, F.E., Luettich, R., Blanton, B.O., Quinlan, J., McGillicuddy, D.J., Ledwell, J.R., Churchill, J., Kosnyrev, V.K., Davis, C.S., Gallager, S.M., Ashjian, C.J., Lough, R.G., Manning, J., Flagg, C.N., Hannah, C.G. and R.C. Groman, 2001. Realtimedata
assimilative modeling on Georges Bank, Oceanography, l4 (1), 65-77.

Lynch, D.R. and D.J. McGillicuddy, 2001.  Objective analysis for coastal regimes. Continental ShelfResearch 211299-1315.

Real-time forecasting and biological data assimilation on Georges Bank. WHOI COFDL seminar, July 1999.

Real-time forecasting and biological data assimilation on Georges Bank, Middle Atlantic Bight Physical Oceanography and Meteorology (MABPOM) Workshop, Woods Hole, MA, October 1999.

Real time forecasting and biological data assimilation on Georges Bank (Invited). AGU/ASLO Ocean Sciences Meeting, San Antonio, TX, January 2000.

Coupled physical-biological modeling in the coastal ocean: from climatology to forecasting. University of Connecticut, Department of Marine Sciences Seminar Series (Invited), February 2000.

Coupled physical-biological modeling and prediction. ONR Bioluminescence Workshop, San Diego, CA (Invited}, February 2000.

Last updated: August 19, 2008

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