ARCTIC SYNTHESISARCTIC SYNTHESIS
Ecosystem Modeling StatusEcosystem Modeling Status
Yvette H. Spitz and LYvette H. Spitz and Léo Berlineéo Berline
OSU-COASOSU-COAS
Chlorophyll a SeaWifs climatology Model 1986
White line : ice edge
Annual primary production
Model 1986 VGPM 1998 (Behrenfeld and Falkowski. 1997)
Observations11-component model
•Coded new ecosystem model Coded new ecosystem model – 2 phytoplankton (pico and diatom) and 2 2 phytoplankton (pico and diatom) and 2
zooplanktonzooplankton– Full microbial loopFull microbial loop– Nitrate, Ammonium and SilicateNitrate, Ammonium and Silicate
• Diagnostic preliminary runs 3DDiagnostic preliminary runs 3D
Nitrate concentration
after one year of run
Problem vertical diffusion• High surface nitrate concentration in the north Chukchi Sea
Time (month)
Dep
th (
m)
− 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
New Eq of State UNESCO Eq of State
Salinity
New Eq of State
UNESCO Eq of State
Temperature
Nitrate initial condition for winter
• Levitus in GIN• Colony in Can Basin• Value from literature on
shelves
Location 1D model Tests
ChukchiSHEBA
Greenland
• 3 different ice cover
Greenland 1D outputs
NO3
Chl
Blue : model, Red: obs (Cota)
Greenland 1D outputs
NO3
Chl
Blue : model, Red: obs (Cota) T-Dependence of growth
Chukchi 1D outputs
July, end of simulation
Blue : model, Red: obs (SBI)
QuestionsQuestions
• GreenlandGreenland– Is nitrate not depleted in summer?Is nitrate not depleted in summer?– Is it general for GIN?Is it general for GIN?
• ChukchiChukchi– Is benthic remineralization important?Is benthic remineralization important?– Need to go further north to avoid Need to go further north to avoid
contamination by Bering Straitcontamination by Bering Strait• Modeled phytoplanktonModeled phytoplankton
– Main taxa: Diatom, auto. Dinoflagellates ok?Main taxa: Diatom, auto. Dinoflagellates ok?– Importance phaeocystis?Importance phaeocystis?– Chl/C Value valid arctic-wide?Chl/C Value valid arctic-wide?
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