Modeling Studies of the Physical-Biological Processes Controlling
Spring Bloom Dynamics on Georges Bank: 1-D and 2-D Experiments
Ji, R.1, C. Chen2, P. J. S.
Franks3, D. W. Townsend4, E.G.
Durbin5, R. C. Beardsley6,
and R. W. Houghton7
1Department of Marine Sciences, University of Georgia, Athens, GA
30602
2School for Marine Science and Technology, University of
Massachusetts-Dartmouth, New Bedford, MA 02744
3Marine Life Research Group, Scripps Institution of Oceanography,
University of California, San Diego, La Jolla, CA 92093-0218
4School of Marine Sciences, 5741 Libby Hall, University of Maine,
Orono, Maine 04469
5Graduate School of Oceanography, University of Rhode Island, South
Ferry Rd, Narragansett, RI 02882
6Department of Physical Oceanography, Woods Hole Oceanographic
Institution, Woods Hole, MA 02543.
7Lamont Doherty Earth Observatory of Columbia University, Palisades,
NY 10964
A coupled biological-physical model has been developed for the Gulf
of Maine (GOM) /Georges Bank (GB) region. The biological model,
based on nutrient and plankton features observed on GB, consists of
9 compartments: nutrients (nitrate, ammonia and silicate),
phytoplankton (large and small size groups), zooplankton (large and
small size groups), detrital organic nitrogen and silicon. The
physical model for 1-D and 2-D experiment is ECOM-si, which is
driven with tidal forcing, wind stress and heat flux. The 1-D model
results show that the physical-biological processes controlling
spring bloom dynamics over GB varies with water depth. In the
shallow and well-mixed regions, the timing of the spring bloom is
sensitive to light intensity and the light attenuation coefficient,
while the magnitude is regulated by the initial nutrient
concentration and zooplankton grazing pressure. In the deeper
regions, the seasonal onset of stratification directly attributes to
the timing of the spring bloom. The 2-D model results indicate that
the spring bloom dynamics in the shallow and well-mixed area of GB
are very similar to the 1-D situation. A 'second' bloom can occur
near the tidal mixing front area due to the seasonal onset of
stratification. The spring bloom in the stratified region seems to
be sensitive to vertical stratification, especially at the
transition time during late spring.
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