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ARCTIC SYNTHESIS Ecosystem Modeling Status Yvette H. Spitz and L é o Berline OSU-COAS. Chlorophyll a. SeaWifs climatology. Model 1986. White line : ice edge. 11-component model. Observations. Coded new ecosystem model 2 phytoplankton (pico and diatom) and 2 zooplankton
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ARCTIC SYNTHESISEcosystem Modeling StatusYvette H. Spitz and Léo BerlineOSU-COAS
Chlorophyll a SeaWifs climatology Model 1986 White line : ice edge
11-component model Observations
Coded new ecosystem model • 2 phytoplankton (pico and diatom) and 2 zooplankton • Full microbial loop • Nitrate, Ammonium and Silicate • Diagnostic preliminary runs 3D
Problem vertical diffusion • High surface nitrate concentration in the north Chukchi Sea Depth (m) Time (month)
Deep mixing that leads to high nutrient in the surface and therefore artificially high bloom. Changed Eq of state in POP (Jacket and McDougall, 1995, instead of the traditional polynomial fit to the UNESCO eqn of state), which improved slightly the density field • Light penetration and mixing seems to pose problems for us - Ice model might need tuning • Open Boundary conditions at the Strait might help to retain some nutrient on the shelf
Salinity UNESCO Eq of State New Eq of State
Temperature New Eq of State UNESCO Eq of State
Nitrate initial condition for winter • Levitus in GIN • Colony in Can Basin • Value from literature on shelves
Location 1D model Tests • 3 different ice cover Greenland SHEBA Chukchi
Greenland 1D outputs Blue : model, Red: obs (Cota) NO3 Chl
Greenland 1D outputs Blue : model, Red: obs (Cota) T-Dependence of growth NO3 Chl
Chukchi 1D outputs Blue : model, Red: obs (SBI) July, end of simulation
Questions • Greenland • Is nitrate not depleted in summer? • Is it general for GIN? • Chukchi • Is benthic remineralization important? • Need to go further north to avoid contamination by Bering Strait • Modeled phytoplankton • Main taxa: Diatom, auto. Dinoflagellates ok? • Importance phaeocystis? • Chl/C Value valid arctic-wide?