|dc.contributor.author||Anderson, Laurence A.||
|dc.description||Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 78 (2009): 77-93, doi:10.1016/j.jmarsys.2009.04.001.||en||
|dc.description.abstract||The objective of this study was to fit a simple ecosystem model to climatological
nitrogen cycle data in the Gulf of Maine, in order to calibrate the biological model
for use in future 3-D modelling studies. First depth-dependent monthly climatologies
of nitrate, ammonium, chlorophyll, zooplankton, detritus and primary production
data from Wilkinson Basin, Gulf of Maine, were created. A 6-box nitrogen-based
ecosystem model was objectively fitted to the data through parameter optimization.
Optimization was based on weighted least squares with model-data misfits nondi-
mensionalized by assigned uncertainties in the monthly climatological estimates.
These uncertainties were estimated as the standard deviations of the raw data from
the 6-meter and monthly bin averages. On average the model fits the monthly means
almost within their assigned uncertainties.
Several statistics are examined to assess model-data misfit. Pattern statistics such
as the correlation coefficient lack practical significance when data errors are large
relative to the signal, as in this application. Thus Taylor diagrams were not found
to be useful. The RMSE and model bias normalized by the data error were found
to be the most useful skill metrics as they indicate whether the model fits the data
within its estimated error.
The optimal simulated nitrogen cycle budgets are presented, as an estimate of the
seasonal nitrogen cycle in Wilkinson Basin, and discussed in context of the available
data.Wilkinson Basin has spring and fall phytoplankton blooms, and strong summer
stratification with a deep chlorophyll maximum near 21 m, just above the nitracline.
The mean euphotic zone depth is estimated to be 25 m, relatively constant with
season. The model estimates annual primary production as 176 g C m−2 yr−1,
annual new production as 71 g C m−2 yr−1 and sinking PON fluxes of 9.7 and 4.7
g N m−2 yr−1 at 24 and 198 m respectively.
Areas for improvement in the biological model, the model optimization method,
and significant data gaps are identified.||en||
|dc.description.sponsorship||This work was supported by ONR, NSF, and NOAA grant to Dennis
|dc.subject||Gulf of Maine||en||
|dc.title||The seasonal nitrogen cycle in Wilkinson Basin, Gulf of Maine, as estimated by 1-D biological model optimization||en||