Remote Sensing in the Coastal Gulf of Maine Abstract

The Gulf of Maine is a semi-enclosed water body with intense coupling between land and sea. It receives large inputs of dissolved and particulate carbon from land run-off as well as the NW Atlantic Ocean. The coupled terrestrial and marine biomes support highly productive ecosystems, as well as extensive agriculture, aquaculture and fisheries. Carbon is the common currency of each system. Interestingly, the connections between the terrestrial and marine carbon budgets are significant to the coastal biomes, yet they remain poorly understood. In this interdisciplinary regional study of the Gulf of Maine and its terrestrial watershed, we are investigating the consequences of climate, sea level changes and increased human activities on the land-sea carbon coupling. Specifically, we are focusing on the connections between vegetation cover, land use, hydrology, climate, regional weather, oceanic circulation, and various terrestrial and marine carbon compounds relevant to the carbon balance. Critical to this work is a thorough understanding of the seasonal to annual fluxes of dissolved and particulate organic carbon from terrestrial sources to the Gulf of Maine via major rivers, and their subsequent fate within the Gulf of Maine. Both types of organic carbon are critical to ocean remote sensing in the Gulf of Maine because of their profound influence on the optical properties of the water.

Several rich data sets (all ongoing) form the basis for this study: 1) 60-100 years of river runoff data available from the U.S. Geological Survey and Environment Canada, 2) a 6 year NASA-sponsored coastal time series of hydrography, bio-optical properties, and carbon cycle properties across the Gulf of Maine, operated from a ferry, 3) a 3-year time series of bio-optical and physical data at several stationary buoy sites throughout the Gulf as part of the Gulf of Maine Ocean Observing System (GoMOOS), and 4) long-term climate records available for temperature and precipitation (from the USHCN) and the North Atlantic Oscillation (NAO) index. We are also undertaking a river sampling component to better understand the DOC sources that feed into the Gulf of Maine , the timing of those inputs, and how land-use change, such as ongoing urbanization and deforestation, or climate change might influence the flux of DOC from the land to the sea. Chemical analyses of the terrestrial and marine water samples, with respect to distinct particulate and dissolved carbon pools, will allow a better understanding of the fluxes, transformations, and turnover of these carbon compounds in the coastal environment. All of the data sources listed above, along with synoptic satellite data, will provide the foundation for scaling-up our observations to the larger space and time scales of variability in the Gulf of Maine ecosystem—a central goal of our proposed work.