|Funded by NASA Ocean Biology & Biogeochemistry and Cryosphere Programs||
Jinlun Zhang and Mike Steele (University of Washington)
Carin J. Ashjian (Woods Hole Oceanographic Institution)
Robert G. Campbell (
Victoria Hill (Old Dominion University)
Yvette H. Spitz
arctic sea ice has been observed in recent
particularly dramatic during summers 2007–2009,
arctic sea ice extent decreased to the lowest
levels observed in the satellite era (1979–present). The dramatic decline
after years of shrinking and thinning of the ice cover, closely linked
increasing surface air temperature (SAT). The ice cover has
in every season and in every sector of the
Despite the extreme polar conditions, the CBS shelves are ranked among the most productive in the world, supporting a complex pelagic food web that includes zooplankton, fish, birds, seals, walruses, whales and the top predator, the polar bear. At the base of the food chain, supporting all the marine life, are the phytoplankton and algae that produce organic carbon. Light, temperature, and nutrients govern the variability of the biological productivity in the CBS. Advection of nutrient-rich Pacific water, input of freshwater and nutrients from rivers, upwelling/downwelling, and cross-shelf exchange between shelf and basin influence biological and chemical distributions and processes in the CBS. Changes in the ice cover affect the penetration of light into the water column, mixing due to wind stirring and buoyancy flux at the ocean surface, the oceanic mixed layer temperature, upwelling and shelf–basin exchange of nutrients, and air–sea exchange of biogenic gases. Thus, the decline of sea ice in the CBS may have a profound effect on the marine ecosystem.
The central science question for our research is “What is the impact of climate change (natural and anthropogenic) on the biogeochemistry and ecology of the Chukchi and Beaufort seas?" as raised by the NASA Ocean Biology & Biogeochemistry Program. Our main hypothesis is that reduction in summer ice cover and changes in upper ocean physics will substantially impact the CBS ecosystem, via changes in primary production, ecosystem structure and function, and alteration in the strength of benthic-pelagic coupling. Our objectives in addressing the central science question and the main hypothesis are:
1) Synthesize the historical evolution of the biology/ice/ocean system in the Chukchi and Beaufort seas from 1978 to the present through modeling and analyses of satellite and in situ observations; quantify and understand the large-scale changes that have occurred in sea ice, upper ocean, and the marine planktonic ecosystem over the shelves and the basin.
2) Identify key linkages and interactions between sea ice, upper ocean, and the planktonic ecosystem to understand how changes in sea ice, water temperature, vertical mixing, and upper ocean stratification affect light availability, nutrient distribution, biogeochemical processes, food-web dynamics, and the strength of benthic-pelagic coupling.
3) Examine how the Chukchi/Beaufort planktonic ecosystem responds to changes in nutrient-rich Pacific water inflow at Bering Strait and advection on the shelves, in the Beaufort shelfbreak jet, and in mesoscale physical processes that enhance shelf-basin exchange such as eddy and filament formation and shelf-break upwelling.
To achieve these
we will conduct observational analyses using satellite ocean color, sea
sea surface temperature (SST) data, and in situ data. We will also
fully coupled 3D high-resolution