University of Massachusetts, Dartmouth: Steve Lohrenz
University of Delaware: Wei-Jun Cai
Auburn University: Hanqin Tian
November 2014 – October 2018
Information about carbon fluxes in continental margins and linkages to terrestrial carbon cycles are key focuses of NASA’s Earth Science Research Program and central aspects of NASA’s Carbon Monitoring System. The uncertainties in coastal carbon fluxes are such that the net uptake of carbon in the coastal margins remains a poorly constrained term in global budgets. In particular, our ability to estimate current air-sea CO2 fluxes in continental margins is limited, and there is even less capability for predicting changes in the CO2 uptake capacity in coastal waters. The need to improve the understanding of coastal carbon dynamics and the precision of estimates of coastal carbon fluxes has implications for attribution of land sources and sinks because atmospheric inversions are sensitive to uncertainties in coastal boundaries. Moreover, characterization of trends in carbon inventories reveal an increasing fraction of fossil fuel carbon is remaining in the atmosphere due to reductions in the efficiencies of ocean sinks and other sink processes not considered in current models. The proposed research will employ a combination of models and remotely-sensed and in situ observations to develop georeferenced products and associated uncertainties for land-ocean exchange of carbon, air-sea exchanges of CO2, and coastal-to-open-ocean exchanges of carbon. Such information is critically needed to better constrain the contribution of coastal margins to carbon sources and sinks and improve capabilities to attribute sources and sinks to different regions as well as reducing uncertainties in estimates. The proposed effort will use a combination of observations and coupled terrestrial and ocean models to examine carbon processes and fluxes from the watershed to the continental margin. A major aspect of this proposed project will be to establish and populate geospatial portals for sharing and analysis of carbon datasets and products. The primary region of study will be the Mississippi River watershed and northern Gulf of Mexico. However, the model domain will also include the continental margins of Florida and the South Atlantic Bight. The region of study provides an excellent setting to carry out this work as there are a large number of supporting datasets and ongoing programs that will complement this work. The proposed work is closely aligned with objectives of the NASA Carbon Monitoring System scoping effort and of the North American Carbon Program and will support National Climate Assessment activities. The effort will also contribute to NASA Coastal Carbon Synthesis effort and international efforts to develop a North American carbon budget (CarboNA). The unique nature of our approach, coupling models of terrestrial and ocean ecosystem dynamics and associated carbon processes, will allow for assessment of how societal and human-related land-cover and land-use changes, as well as climate change, affect terrestrial carbon sources and sinks, export of materials to coastal margins, and associated carbon processes in the continental margins. Results would also benefit efforts to describe and predict how land cover and land use changes impact coastal water quality, including possible effects of coastal eutrophication, hypoxia, and ocean acidification.
The OOMG group, working closely with Dr. Lohrenz’s group, will 1) conduct coupled DLEM-SABGOM ROMS simulations to investigate the impact of land use and watershed hydro-biogeochemical processes to marine ecosystem variability; 2) provide model-based estimations of air-sea CO2 flux and organic and inorganic carbon flux exchange between shelf and open seas in the southeastern U.S. coastal ocean by using the coupled physical-biogeochemical modeling system; 3) perform model-data comparisons, characterize and quantify errors and uncertainties in carbon fluxes associated with the algorithms and parameters of ocean model, input data, and model coupling; and 4) develop an online, user-friendly data interface to serve model results and derived products to facilitate information exchange and carbon monitoring-related decision making.
The web site An Integrated Terrestrial-Coastal Ocean Observation and Modeling Framework for Carbon Management Decision Support has been created to inform the public about the project and its products.