PMEL Programs and Plans
Accomplishments in FY 97 and Plans for FY 98
 
Figure. Depth sections of (a) Dissolved inorganic carbon and
(b) salinity for January - March 1996, at 170W.
Carbon Dioxide Program
Accomplishments in FY 97
The decadal to centenial component of NOAA's Climate and Global Change
(C&GC) Program addresses the need to assess and predict changes in
climate on time scales of 10 to 100 years. One of the major components
of this program concerns the climatic impact of the anthropogenic
production of "greenhouse gases" such as carbon dioxide (CO2). CO2 is
estimated to be responsible for roughly one-half of the "greenhouse gas"
effect resulting from anthropogenic inputs of trace gases to the
atmosphere. Because CO2 in the atmosphere absorbs long-wave radiation
emitted from the earth's surface, the post-industrial increase of CO2
will have the effect of producing a higher equilibrium temperature of
the troposphere. Credible prediction of the magnitude of this
temperature increase is a high priority scientific issue. Recent model
predictions suggest an increase of global mean surface temperature of
1.5-4.0°C in the next century for a doubling of atmospheric CO2. Future
decisions on regulating emissions of "greenhouse gases" should be based
on more accurate models which have been adequately tested against a well
designed system of measurements. Predicting global climate change as a
consequence of CO2 emissions requires coupled atmosphere/ocean/bioshpere
carbon models that realistically estimate the rate of growth of CO2 in
the atmosphere, as well as its removal, redistribution and storage in
the oceans and terrestrial biosphere.
The primary objective of NOAA's Ocean Atmosphere Carbon Dioxide Exchange
Study (OACES) is to quantitatively assess the fate of CO2 in the
atmosphere and oceans. In order to accomplish this goal the natural
sources and sinks of carbon dioxide must be determined. During FY 97,
the PMEL CO2 group determined the distribution of pCO2 in the equatorial
Pacific during the 1997-98 ENSO event. Throughout the event pCO2 values
showed a sharp decrease along the eastern edge of the warm pool which
moved from west to east along the equator as the event developed. Thus,
the position of the warm pool played a dominant role in controling the
CO2 flux during 1997. The impact of this extreme ENSO event was more
than a factor of 2 lower CO2 flux from the equatorial Pacific during
1997 as compared with the previous year.
Carbon Dioxide Program
Plans for FY 98
During FY 98, the Ocean-Atmosphere Carbon Exchange Study will provide
data reduction and synthesis of the current field data in the Atlantic,
Pacific and Indian Oceans, in collaboration with the participants of the
DOE-CO2 Survey Science Team. In particular, the group will compare
datasets with data obtained on other WOCE-WHP cruises and will provide
internally consistent datasets encompassing roughly sixteen cruises in
the Pacific Ocean, fifteen cruises in the Indian Ocean, and ten cruises
in the Atlantic. These datas will be used by the modeling community for
setting boundary conditions for general ocean circulation models, to
determine the DIC inventory in each basin using several independent
methods as outlined in Wallace (1995), and to estimate anthropogenic CO2
increases in the ocean Gruber et al., (1996) To facilitate comparisons
of models and observations, the data will be gridded into similar box
sizes as currently used in the models.
CO2 fluxes between air and water are poorly constrained because of lack
of seasonal and geographic coverage of pCO2 (air-water disequilibrium)
values and incomplete understanding of factors controlling the air-sea
exchange. In addition to intensive monitoring of carbon parameters and
parameters influencing pCO2 levels in surface water on dedicated cruises
sponsored by OACES, PMEL, and AOML have outfitted the NOAA Ship
Ka'imimoana with a new automated CO2 system to monitor surface water
pCO2 on a continuous basis. While this effort has been a success we need
more CO2 systems on NOAA ships to obtain the large area coverage. The
new shipboard design, patterned after the systems recently built at AOML
and PMEL, uses stop-flow technology to reduce the amount of gas required
for analysis by the LICOR detector. It will be improved to facilitate
fully autonomous operation. The improvements will include automating
draining of water traps, comprehensive self diagnostics by the program
running the computer, and automatic rebooting capabilities of the system
if errors are detected. The underway system will be an integrated
package for measurement of pCO2 in air and water and support sensors
necessary to reduce the data (such as equilibrator temperature,
location, salinity, sea surface temperature, and barometric pressure).
The comprehensive automated package will facilitate operations on ships
of opportunity. The NOAA Ship Ka'imimoana, used to maintain the TAO
moorings on six month intervals, offers an excellent opportunity to
determine seasonal and secular trends in the region.
In addition to this activity, we will continue our pCO2 instrument
development activities with the group at MBARI , directed by Francisco
Chavez, to provide a suite of chemical and biological sensors deployed
on the 155W and 170W TAO morring array in the equatorial Pacific in
November of 1997. The work leverages on developmental efforts carried
out by MBARI (with support from NOAA, NASA, and PMEL) over the past
several years. The primary objectives of this project are: (1) to
determine the relationships between physical forcing, primary production
and the exchange of carbon dioxide between ocean and atmosphere; (2) to
determine the biological and chemical responses to climatic and ocean
variability in the equatorial Pacific; (3) to determine the spatial,
seasonal and interannual variability in primary production, carbon
dioxide, and nutrient distributions; and (4) to determine the spatial,
seasonal and interannual variability of sea surface pigment
distributions to groundtruth sattelite measurements of ocean color.
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