U.S. Eastern Continental Shelf Carbon Budget: Modeling, Data Assimilation, and Analysis U.S. ECoS Science Team*

1
U.S. Eastern Continental Shelf Carbon Budget
Modeling, Data Assimilation, and Analysis U.S.
ECoS Science Team
ABSTRACT. The U.S. Eastern Continental Shelf
Carbon Budget (U.S. ECoS) Program, which began in
summer 2004, is funded as part of the NASA
Interdisciplinary Science Program. The overall
goal of this project is to develop carbon budgets
for the Mid-Atlantic Bight (MAB) and South
Atlantic Bight (SAB) along the eastern U.S.
coast. The U.S. ECoS program is structured
around five themes which are focused on 1)
development and implementation of circulation,
biogeochemistry, and carbon cycling models for
the east coast of the U.S. 2) analyses of
historical in situ measurements and
satellite-derived data 3) a limited field
measurement effort designed to provide
measurements for input to the biogeochemistry and
carbon cycling models 4) development and
implementation of data assimilative
biogeochemical and carbon cycling models and 5)
interfacing the circulation, biogeochemistry and
carbon cycling models with climate models. Our
research is particularly germane to NASAs carbon
cycle research focus topic and coastal research
initiative and the U.S. Climate Change Research
Program, all of which emphasize the North
American Carbon Program.
U.S. ECoS Science Team Eileen Hofmann (ODU)
Project oversight, 1D modeling Marjorie
Friedrichs (ODU) Modeling, data
assimilation Chuck McClain (GSFC) Project
oversight, satellite data Sergio Signorini (GSFC)
Satellite data analyses Antonio Mannino (GSFC)
Carbon cycling Cindy Lee (Stony Brook)
Carbon cycling Jay OReilly (NOAA) Satellite
data analyses Dale Haidvogel (Rutgers)
Circulation modeling John Wilkin (Rutgers)
Circulation modeling Katja Fennel (Rutgers)
Biogeochemical modeling Sybil Seitzinger
(Rutgers) Food web, nutrient dynamics Jim Yoder
(WHOI) Food web, nutrient dynamics Ray Najjar
(Penn State) Data climatology, climate
modeling David Pollard (Penn State) Climate
modeling

• RESEARCH
  QUESTIONS
• What are the relative carbon inputs to the MAB
  and SAB from terrestrial sources and in situ
  biological processes?
• 2) What is the fate of DOC input to the
  continental shelf from estuarine and riverine
  systems?
• 3) What are the dominant food web pathways that
  control carbon cycling and flux in this region?
• 4) Are there fundamental differences in the
  manner in which carbon is cycled on the MAB and
  SAB continental shelf?
• 5) Is the carbon cycle of the MAB and SAB
  sensitive to climate change?

Figure 4
Sink
Figure 2 Simulated Chlorophyll
Source
Latitude (North)
Figure 1
Figure 5
Figure 2 SeaWiFS Chlorophyll
Longitude (West)
Comparisons of simulated, in situ, and
SeaWiFS-derived monthly-averaged chlorophyll
concentrations at sites in the MAB (Figure 4).
The biogeochemical model captures the chlorophyll
annual cycle. The simulated annual air-sea CO2
flux shows that the MAB and SAB provide a net
sink for carbon (Figure 5). Additional
simulations are ongoing to investigate carbon and
nutrient cycling processes in the MAB and SAB.
The biogeochemical model used in this project
(Figure 1) is coupled to a circulation model
(Regional Ocean Modeling System, ROMS v.3) that
has been implemented for the continental shelf
and adjacent deep ocean of the U.S. east coast
(Northeast North American (NENA) Shelf Model).
Comparisons of simulated chlorophyll
distributions obtained with the coupled
circulation-biogeochemical model show features
that are similar to those seen in chlorophyll
distributions obtained from SeaWiFS measurements
(Figures 2,3). The biogeochemical model is
currently being modified to include data
assimilation capability.
Figure 3
Figure 7
Figure 9
Satellite data analyses are an integral part of
the project and provide inputs and verifications
for the simulated distributions obtained from the
coupled model, such as the Western North Atlantic
POC composite (mg C L-1, log scale is 0.01 to
5.0) for April 1998 (Figure 6) derived from
SeaWiFS normalized water leaving radiances and
the Clark empirical algorithm (D. Clark,
unpublished). The nearshore sources (yellow-red
high values) originate from rivers and estuaries.
Lowest values are in the Sargasso Sea and
patchiness south of the Gulf Stream may be due to
POC advection by cold core eddies.
The field sampling component of the U.S. ECoS
project is focused on Chesapeake Bay (Figure 9)
and provides data sets that are critical for the
biogeochemical model. Initial results show lower
DOC variability in summer-fall than in
winter-spring (Figure 9).
Satellite-derived data sets provide distributions
of seasonal and interannual variability in
primary production (Figures 7, 8) and estimates
of primary production obtained from different
algorithms (Figure 7). In situ data sets, such
as the MARMAP data, provide calibration for the
satellite-derived values (Figure 7).
Figure 8
This project is supported by the NASA
Interdisciplinary Science Program
Figure 6
Interannual Ecosystem Variability
J. OReilly, NMFS, NOAA