Friedrichs, M. A.M.. Old Dominion University, marjy@ccpo.odu.edu
Hofmann, E. A.M.. Old Dominion University, hofmann@ccpo.odu.edu

 
ASSIMILATION OF BIOLOGICAL DATA INTO A BIOLOGICAL-PHYSICAL MODEL OF THE CENTRAL EQUATORIAL PACIFIC
 
A one-dimensional, five-component biological-physical model of the equatorial Pacific is run in a data-assimilative mode using the adjoint method. Through the assimilation of SeaWiFS ocean color data and JGOFS EqPac cruise data (4/92 and 10/92), it is possible to recover grazing, growth, mortality and recycling parameters, as well as the half-saturation coefficient for iron uptake. When data from the first EqPac time series cruise are assimilated, independent primary production and f-ratio data correspond well to modelled results. However, assimilation of data from the second EqPac time series cruise results in the recovery of an unreasonable parameter set and produces primary productivities and f-ratios that are in poor agreement with observations. As a result, we conclude that the model contains the first-order dynamics necessary to describe the ecosystem during the first cruise only. Ancillary EqPac observations indicate that the passage of a tropical instability wave during the second cruise caused a significant change in species composition, a condition for which our model does not allow. This exercise provides an example of how data assimilation in physical-biological models can be used to systematically determine whether or not observations are consistent with a given set of ecosystem dynamics.
 
Day: Monday, Feb. 1
Time: 04:30 - 04:45pm
Location: Eldorado Hotel
 
Code: SS44MO0430E