Nevison, Cynthia (Cindy): University of Colorado/INSTAAR (Project Lead)
Project Funding:
2007 - 2010
NRA: 2006 NASA: Ocean Biology and Biogeochemistry
Funded by NASA
Abstract:
The Southern Ocean is a key region contributing to the regulation of both atmospheric
CO2 concentrations and deep ocean O2 levels through the efficiency of the "biological
pump", in which carbon is fixed and exported out of the surface mixed layer into the
ocean interior. Deepwaters become enriched in CO2 and depleted in O2 due to subsurface
remineralization and later ventilate and equilibrate with atmospheric CO2 and O2 when
they outcrop to the surface. In support of the Data Synthesis, Assimilation, and Modeling
component of NASA's Southern Ocean Carbon Program, we propose a synthesis of
satellite-based ocean color and temperature, in situ ocean data, and atmospheric O2/N2
and N2O measurements to provide improved estimates of export flux and subsurface
ventilation of the Southern Ocean. The satellite data will be incorporated into improved
algorithms to generate time-series of ocean phytoplankton photosynthetic pigments, net
primary production (NPP), and export flux (ƒ) ratios. The improved f ratios will be
guided by analysis of a large new database of Th isotope and sediment trap measurements
in the Southern Ocean. The export fluxes, calculated as the product of NPP * ƒ, will be
combined with a simple mixed layer balance to estimate air-sea O2 fluxes, which will be
used to force an atmospheric tracer transport model. The model results will be compared
to atmospheric O2/N2 observations at southern hemisphere monitoring stations that have
been corrected for thermal and terrestrial signals using standard methods as well as for
biological O2 ventilation signals based on a new method involving atmospheric N2O.
Simulations will focus initially on evaluating the ability of export flux algorithms to
reproduce mean seasonal cycles in atmospheric O2/N2 and later will be extended to
examine interannual variability. An important product of the latter analysis will be a
synthesis of satellite data and O2/N2 measurements to create an index of the atmospheric
signal of the subsurface ventilation of the Southern Ocean and its variation from year to
year. The integrated research specifically addresses Strategic Sub-goals 3.A.3 and 3A.6
of NASA's Strategic Science Outcomes by using remotely sensed data to contribute to
progress in quantifying marine productivity and in understanding the role of the oceans in
the climate system.
2008 NASA Carbon Cycle & Ecosystems Joint Science Workshop Posters
- Spatial and temporal variability in chlorophyll, primary production and export production in the Southern Ocean
-- (B. Greg Mitchell, Mati Kahru, Haili Wang, Ralph Keeling, Matt Charette, Cynthia Nevison)
[abstract]
- Southern Ocean export flux and air-sea O2 exchange: A synthesis of atmospheric O2/N2 measurements, satellite data and direct observations
-- (Cynthia D Nevison, Matthew A Charette, Mati Kahru, Ralph F Keeling, Kanchan Maiti, Brian Gregory Mitchell)
[abstract]
[poster]
More details may be found in the following project profile(s):
