NASA logo

Planktonic Ecosystem Response to Changing Sea Ice and Upper Ocean Physics in the Chukchi and Beaufort Seas: Modeling, Satellite and In Situ Observations


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 (University of Rhode Island)
Victoria Hill (Old Dominion University)
Yvette H. Spitz (Oregon State University)



Home
Introduction Model
Data
Source Code
Publications
Links

Introduction (under construction)

Significant decline of arctic sea ice has been observed in recent years. The decline was particularly dramatic during summers 2007–2009, when the arctic sea ice extent decreased to the lowest levels observed in the satellite era (1979–present). The dramatic decline occurred after years of shrinking and thinning of the ice cover, closely linked to increasing surface air temperature (SAT). The ice cover has been shrinking in every season and in every sector of the Arctic Ocean. However, the summer ice retreat during 2007–2009 was most severe in the Pacific sector including the Chukchi and Beaufort seas (CBS), indicating that sea ice in that region may be particularly vulnerable to arctic warming.

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 goals we will conduct observational analyses using satellite ocean color, sea ice, and sea surface temperature (SST) data, and in situ data. We will also develop a fully coupled 3D high-resolution Biology/Ice/Ocean Modeling and Assimilation System (BIOMAS) for synthesis and modeling of the Chukchi and Beaufort seas. BIOMAS will combine advanced sea ice and ocean models with a tested arctic marine planktonic ecosystem model (Zhang et al. 2010) and assimilate satellite sea ice concentration and SST. SeaWiFS-derived chlorophyll and primary productivity and in situ biophysical data will be used for model calibration/validation. This unique system will enhance our understanding of how the planktonic ecosystem responds to changing sea ice and upper ocean physics in the Chukchi and Beaufort seas. Our work is part of the NASA Impacts of Climate change on the Eco-Systems and Chemistry of the Arctic Pacific Environment (ICESCAPE) project which aims to pursue the above central science question and associated issues through an interdisciplinary, cross cutting approach integrating field expeditions, modeling, and satellite remote sensing.


Movies:


Contact: If you have any questions or require additional information,  please contact any of the collaborative PIs: Jinlun ZhangMike Steele, Yvette Spitz, Carin Ashjian, Robert Campbell, and Victoria Hill.

Home
Introduction Model
Data
Source Code
Publications
Links