The Carbon Balance of Lake Superior

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Collaborative Research: The carbon balance of Lake Superior: modeling lake processes and understanding impacts on the regional carbon budget

Principle Investigator:	Noel Urban
Sponsor:	NSF
Award Amount:	$242,199
Project Duration:	8/1/2006-7/31/2010
MTU Reference Code:	060332

Collaborative Research including:

Galen A. McKinley, Chin Wu, and Ankur Desai of University of Wisconsin - Madison
Noel Urban of Michigan Technological University

Intellectual Merit
The North American Carbon Program (NACP) intends (1) to develop quantitative scientific knowledge, robust observations, and models to determine emissions and uptake of CO2, CH4, and CO1 changes in carbon stocks, and factors regulating these processes for North America and adjacent ocean bsins; and (2) to develop the scientific basis for full carbon accounting on regional and continental scales. The Laurentian Great Lakes over 25% of the land area of the 8 Great Lakes states, and CO2 emission and seasonal cycling from them may be comparable to local terrestrial ecosystems. THough theri contributions to the regional carbon balance may be significant, these fluxes are currently poorly understood. CO2 fluxes from Lakes Superior are of particular interest because they may directly impact observations at nearby AmeriFlux towers, yet due to lack of quantificaiton, Lake Superior fluxes are currently neglected in analysis of these data.

Motivated by the need for improved knowledge of Great Lake CO2 fluxes, we will couple an exosystem-carbon module to an existing hydrodynamic model of Lake Superior to estimate these fluxes and their spatial and temporal variability. We will also obtain new wintertime observations of carbon parameters in the lake to constrain this model. Using model output, we will evaluate the impact of lake Superior CO2 fluxes on observations at AmeriFlux towers and on the regional carbon budget. Through this work, we will address five key research questions:

What is the magnitude of the air-water carbon flux in Lake Superior?
How are the fluxes influcenced by variability in the physical climate?
How does Lake Superior's carbon cycle behave in winter?
What are the most important uncertainties in the Lake Superior carbon budget?
How do Lake Superior carbon fluxes impact the regional carbon budget?

Through this project, an interdisciplinary team will deelop improved understanding of the "complex reationships between and within the global water and carbon cycles". By jointly considering coastal carbon processing and terrestrial carbon budgets, this project addresses the research priorities of both th4e Ocean Sciences and Earth Sciences dvisions.

Broader Impacts
This project will address fundamental questions about the upper Midwest carbon budget, improve knowledge of near-shore carbon cycling, and generate a set of research priorities for future study of Great Lake carbon cycling. A student and postdoc will be educated in ecosystem-physical modeling of the Great Lakes, and the project will increase regional collaborations for Great Lakes carbon science. Undergraduates from under-represented groups will actively participate in the project through MTU's REU program. We will also make efforts to communicate our findings to the general public.