|
Dissolved organic carbon fluxes and stocks in the Mid-Atlantic Bight
Sergio
Signorini, NASA GSFC, sergio.signorini@nasa.gov
(Presenter)
Antonio
Mannino, NASA GSFC, antonio.mannino@nasa.gov
John
Wilkin, Rutgers University, wilkin@marine.rutgers.edu
Marjorie
Friedrichs, Virginia Institute of Marine Science, marjy@vims.edu
Raymond
Najjar, The Pennsylvania State University, rgn1@psu.edu
Continental margins play an important role in global carbon cycle accounting for 10-30% of the global marine primary production while comprising only 7-10% of the global ocean surface area. These regions are a net carbon sink of atmospheric CO2 on the order of 0.25 Pg C yr-1. Since carbon fluxes across continental margins from land to the open ocean are not well constrained, we developed satellite algorithms to retrieve dissolved organic carbon (DOC) in order to apply satellite data and physical circulation models to quantify the along-shelf and cross-shelf fluxes of DOC for the U.S. Middle Atlantic Bight (MAB). Satellite DOC was computed through seasonal relationships with chromophoric dissolved organic matter absorption (aCDOM). The multi-year time series of satellite-derived DOC stocks shows that freshwater discharge modulates the magnitude and seasonal variability of DOC on the continental shelf.
A neural networks (NNet) model was developed and trained with concurrent in situ temperature (T), salinity (S), and DOC data to reproduce the observed DOC vertical profiles with minimized uncertainty. The NNet model was then applied with circulation model inputs (T and S profiles) to get the DOC profiles at each month and grid point. The profiles were then normalized by their maximum value and re-quantified using the near-surface satellite DOC. Tracer DOC fluxes were computed using circulation model velocities and the satellite-based DOC profiles.
On average (2010-2012), the integrated DOC tracer fluxes at the domain boundaries are 12 Tg C yr-1 at the southwestern boundary (transect near Cape Hatteras, NC) into the MAB, 19 Tg C yr-1 at the northeastern boundary (transect near Georges Bank) into the MAB, and 29 Tg C yr-1 at the cross-shelf along the 100-m isobaths out of the MAB. The corresponding average total estuary export of DOC into the MAB shelf is ~1 Tg C yr-1. The MAB shelf export of DOC is only 3 Tg C yr-1 less than the sum of all DOC inputs (32 Tg C yr-1). Other processes that may contribute significantly to the DOC budget are net biological production, photodegradation, and loss to sediments.
Presentation Type: Poster
Session: Carbon Monitoring System (CMS) Posters
(Mon 1:30 PM)
Associated Project(s):
- Friedrichs, Marjy: Impacts of Changing Climate and Land Use on Carbon Cycling and Budgets of the Coastal Ocean Margin: Observations, Analysis, and Modeling ...details
- Hofmann, Eileen: Impacts of Changing Climate and Land Use on Carbon Cycling and Budgets of the Coastal Ocean Margin: Observations, Analysis, and Modeling ...details
Poster Location ID: 170
|