Balch, William (Barney): Bigelow Laboratory for Ocean Sciences (Project Lead)
Rouhani, Shabnam: Umass Boston (Participant)
Project Funding:
2014 - 2018
NRA: 2013 NASA: Carbon Cycle Science
Funded by NASA
Abstract:
This project will continue the Gulf of Maine North Atlantic Time Series (GNATS) which is a 35+year, NASA-centric, field program that crosses the Gulf of Maine (GoM) to collect bio-optical, hydrographical, biological, biogeochemical and chemical (including carbon-relevant) data for use in satellite calibration/validation studies, as well as a long-term transect time series. We propose to use a combination of satellite and GNATS data (shipboard and autonomous underwater vehicle measurements) to constrain a coupled physical/ecosystem model of the GoM carbon cycle. The overall significance of this is that GNATS has provided critical calibration/ validation data for SeaWiFS, MODIS, and VIIRS sensors, as well as insights about the long-term oceanographic carbon cycle changes in the GoM, a semi-enclosed shelf sea, with strong land-sea connections via 25 surrounding watersheds. We direct this proposal to the second research theme of the NASA ROSES-13 Carbon Cycle Science program: carbon dynamics along terrestrial-aquatic interfaces, including land-ocean, land-freshwater, and coastal ocean regions. This is because of the major importance of river runoff to the physical, chemical, optical and biological oceanography of the GoM, including its carbon cycle. This work is primarily relevant to NASA (given the NASA-centric GNATS sampling) and secondarily to NOAA, specifically for work on productivity, algal biomass, and phytoplankton functional groups of U.S. coastal waters, as well as calibration/validation of the NPP/VIIRS sensor. Along with a whole host of environmental variables, GNATS measures all four parts of the marine carbon cycle: particulate organic carbon (POC), particulate inorganic carbon (PIC; calcite), dissolved organic carbon (DOC), and dissolved inorganic carbon (DIC; e.g., CO2, HCO3-, and CO3=, which are coupled to pH and alkalinity). These four parts of the carbon cycle (including reservoirs and fluxes) provide insights about the major processes affecting the coastal ocean, from changes in productivity (i.e. POC variability through time associated with changes in hydrography, different phytoplankton functional groups, etc.), land-sea carbon transport (i.e. DOC and POC variability caused by major riverine flood events and droughts), and changes associated with ocean acidification (i.e. variability in DIC and PIC caused by changes in carbonate saturation). Simply put, the only way to predict changes to all four parts of the marine carbon cycle as a function of long-term climate change will be through a combined measurement and modeling approach. The ecosystem model to be used for the Gulf of Maine carbon cycle consists of size-structured carbon pools of detrital material, phytoplankton functional types ranging from picoplankton to microplankton, and a size-based zooplankton predator group. Interactions between components will be determined by both size and functional role, and the model will be forced by GoM physical conditions. We will validate the model against GNATS data, and test the ability of remotely-sensed particle size distributions, coupled with the ecosystem model, to reproduce the observed dynamics. We will then use the model to test hypotheses regarding the fate of carbon resulting from climate-driven changes such as increased precipitation and temperature. Anticipated scientific outcomes from this work will be a) a longer duration, NASA-centric, coastal time series that can resolve climatological phenomena spanning time scales of days to decades and b) a coupled physical/ecosystem model based on GNATS that uses remotely-sensed, ship and autonomous underwater vehicle data to constrain the model and test hypotheses relevant to each part of the GoM carbon cycle and the impacts of climate change.
Publications:
Balch, W. M., Bowler, B. C., Drapeau, D. T., Lubelczyk, L. C., Lyczkowski, E. 2018. Vertical Distributions of Coccolithophores, PIC, POC, Biogenic Silica, and Chlorophyll a
Throughout the Global Ocean. Global Biogeochemical Cycles. 32(1), 2-17. DOI: 10.1002/2016GB005614
Balch, W., Huntington, T., Aiken, G., Drapeau, D., Bowler, B., Lubelczyk, L., Butler, K. 2016. Toward a quantitative and empirical dissolved organic carbon budget for the Gulf of Maine, a semienclosed shelf sea. Global Biogeochemical Cycles. 30(2), 268-292. DOI: 10.1002/2015GB005332
Collister, B. L., Zimmerman, R. C., Sukenik, C. I., Hill, V. J., Balch, W. M. 2018. Remote sensing of optical characteristics and particle distributions of the upper ocean using shipboard lidar. Remote Sensing of Environment. 215, 85-96. DOI: 10.1016/j.rse.2018.05.032
Hopkins, J., Balch, W. M. 2018. A New Approach to Estimating Coccolithophore Calcification Rates From Space. Journal of Geophysical Research: Biogeosciences. 123(5), 1447-1459. DOI: 10.1002/2017JG004235
Huntington, T. G., Balch, W. M., Aiken, G. R., Sheffield, J., Luo, L., Roesler, C. S., Camill, P. 2016. Climate change and dissolved organic carbon export to the Gulf of Maine. Journal of Geophysical Research: Biogeosciences. 121(10), 2700-2716. DOI: 10.1002/2015JG003314
Mitchell, C., Hu, C., Bowler, B., Drapeau, D., Balch, W. M. 2017. Estimating Particulate Inorganic Carbon Concentrations of the Global Ocean From Ocean Color Measurements Using a Reflectance Difference Approach. Journal of Geophysical Research: Oceans. 122(11), 8707-8720. DOI: 10.1002/2017JC013146
Record, N. R., Balch, W. M., Stamieszkin, K. 2019. Century-scale changes in phytoplankton phenology in the Gulf of Maine. PeerJ. 7, e6735. DOI: 10.7717/peerj.6735
More details may be found in the following project profile(s):
