MEASUREMENTS OF HYDROGEN ISOTOPES IN ATMOSPHERIC METHANE FROM A SAMPLING OF NOAA FLASK NETWORK SITES
Description:
We present preliminary results from hydrogen isotopic
measurements in atmospheric methane obtained from the NOAA CCGG Cooperative Air
Sampling Network. Recent developments at INSTAAR, University of Colorado
have brought on line the capability to measure hydrogen deuterium ratios in
methane using continuous flow mass spectrometry coupled with an extraction combustion
sample preparation system. Preliminary results show reproducibility of cylinder
air samples to less than ± 2 ‰. Data from several months of samples from six
network sites are presented, including data from: Barrow and Cold Bay, Alaska,
U.S.A; Tutuila American Samoa; Black Sea, Constanta, Romania; Park Falls
Wisconsin, U.S.A.; and Baltic Sea, Poland.
Author's Names: M. Dreier, B.H. Vaughn, J.W.C. White, and K. Mack
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ESTIMATION OF ATMOSPHERIC CO2 FROM AIRS INFRARED SATELLITE RADIANCES IN THE ECMWF DATA ASSIMILATION
Description:
Atmospheric
CO2 concentrations have been obtained from the Atmospheric Infrared
Sounder (AIRS) radiance data within the European Centre for Medium-Range
Weather Forecasts (ECMWF) data assimilation system. In a first explorative
configuration, a subset of channels from the AIRS instrument has been
assimilated providing estimates of tropospheric column-averaged CO2
mixing ratios representative of a layer between the tropopause and about 700
hPa at observation locations only. Results show considerable geographical and
temporal variability with values ranging between 370 and 382 ppmv. The 5-day
mean estimated random error is about 1%, which is confirmed by comparisons with
flask observations on board flights of Japanese airliners in the west-Pacific
region. This study demonstrates the feasibility of global CO2
estimation using high spectral resolution infrared satellite data in a
numerical weather prediction data assimilation system. Currently, the system is
being improved to treat CO2 as a full three-dimensional atmospheric
variable included in the forecast model. This allows more flexibility in the
constraints on the CO2 estimation as well as the possibility of
assimilating other data sources (e.g., near-infrared satellite data and
flasks). The CO2 fields provided by the data assimilation system
have great potential to assist the surface flask network in constraining
current top-down carbon flux estimates.
Author's Names: Richard J. Engelen
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CLIVAR CO2 REPEAT HYDROGRAPHY PROGRAM: INITIAL CARBON RESULTS FROM THE NORTH PACIFIC
Description: We have employed a
Multi-parameter Linear Regression (MLR) analysis procedure to determine the
uptake of anthropogenic CO2 between two east-west hydrographic
surveys of the North Pacific that occurred in 1994 and 2004. The results
revealed water column integrated uptake rates of anthropogenic CO2
that ranged from 1.1 to 1.3 mol m-2 yr-1 depending on
location. The combined effect of the tilted density surfaces and the younger
waters with higher anthropogenic CO2 concentrations leads to higher
total column inventories in the western North Pacific.
Author's Names: R. A. Feely, C. L. Sabine, T. Ono, R. Key, et al
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MARINE ANTHROPOGENIC CO2 ESTIMATES STEMMING FROM OBSERVATIONS
Description:
Anthropogenic CO2 releases to the
atmosphere have changed the total inorganic carbon concentration of ocean by no
more than 3-4% at any location. Main differences between three approaches [Poisson and Chen, 1987; Gruber et al.,
1996; Friis, 2005] are presented that define
marine anthropogenic CO2 (CTant)
as deduced from total inorganic carbon. All definitions are based on a
back-calculation technique that was independently proposed by Brewer [1978] and
Chen and Millero [1979]. The overall importance of this presentation is in the
comparability of anthropogenic CO2 findings from described methods
with these derived from global bookkeeping approaches or full carbon model
results.
Author's Names: Karsten Friis and Raymond G. Najjar
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WHAT CAN TRACER OBSERVATIONS IN THE CONTINENTAL BOUNDARY LAYER TELL US ABOUT SURFACE-ATMOSPHERE ...
Description:
There
are two basic approaches for inferring surface-atmosphere exchange for trace
gases on regional scales: a bottom-up approach, in which local process
knowledge is scaled up, and a top-down approach, in which the larger-scale
constraint from atmospheric concentration measurements is applied in
combination with transport models. Here we combine the two approaches, and
assess the information content added by boundary layer concentration data. More
specifically, we analyze the potential for inferring spatially resolved surface
fluxes from atmospheric tracer observations within the mixed layer, such as
from monitoring towers, using a receptor oriented transport model (Stochastic
Time-Inverted Lagrangian Transport [STILT] model, [Lin et al., 2003]) coupled to a
simple biosphere in which CO2 fluxes are represented as functional responses to
environmental drivers (radiation and temperature, [Gerbig et al., 2003]). Transport and
fluxes are coupled on a dynamic grid using a polar projection with high
horizontal resolution (~20 km) in near field, and low resolution far away (as
coarse as 2000 km), reducing the number of surface pixels without significant
loss of information. To test the system, and to evaluate the errors associated
with the retrieval of fluxes from atmospheric observations, a pseudo data
experiment was performed. A large number of realizations of measurements
(pseudo data) and a priori fluxes was generated, and for each case spatially
resolved fluxes were retrieved. Results indicate strong potential for high
resolution retrievals based on a network of tall towers, subject to the
requirement of correctly specifying the a priori uncertainty covariance,
especially the off diagonal elements that control spatial correlations.
Author's Names: C. Gerbig, J.C. Lin, J.W. Munger, and S.C. Wofsy
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PRECISE MEASUREMENT OF BACKGROUND 14CO2
Description:
Measurements
of the radiocarbon content of atmospheric carbon dioxide are a potentially
powerful, yet relatively unexplored method of improving the understanding of
natural carbon dynamics and verifying fossil fuel emissions. Development of 14CO2
as a tracer has been limited by measurement capabilities given that seasonal
and spatial variation in D14C is
currently of the same order as traditional instrument precision: 3-5 per mil.
We have demonstrated 1-2 per mil reproducible measurement precision at the
Center for Accelerator Mass Spectrometry of Lawrence Livermore National
Laboratory. Here we present preliminary measurements of the natural variability
of 14CO2 from the SIO network of background air sampling
stations.
Author's Names: H.D. Graven, T.P. Guilderson, R.F. Keeling, and C.D. Keeling
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ANTHROPOGENIC CARBON DIOXIDE EMISSIONS AT THE STATE AND MONTHLY LEVELS
Description: CO2 emissions
from fossil-fuel combustion can be estimated at the state or monthly level even
when full data on fuel combustion are not available. Our hypothesis is that a
representative proxy can accurately estimate the pattern of CO2
emissions if a sufficient fraction of the total can be represented, even if the
dataset used does not cover all energy consumption sectors. Our
approach employs monthly sales data for each state from the U.S. Department of
Energy’s Energy Information Administration (EIA). This is used to estimate the
relative proportions of solid, liquid and gaseous fossil fuels for each state
for each month.
Author's Names: J. Gregg, L. Losey, R. Andres, G. Marland
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OCEANIC SOURCES AND SINKS FOR ATMOSPHERIC CO2
Description: Owing to the combination of greatly improved observational constraints
and new data analysis and modeling techniques, our ability to constrain the
role of the ocean in the global carbon cycle has made great advances in the
past decade. By combining ocean interior carbon data with ocean general
circulation models in an inverse manner, we can constrain the oceanic uptake of
anthropogenic CO2 to within an unprecedented narrow range of
2.20±0.25 Pg C yr-1 for a nominal year of 1995. The inversely
estimated pre-industrial air-sea fluxes reveal the expected pattern with CO2
outgassing in the tropics and CO2 uptake at mid to high latitudes.
The subpolar regions of the Southern Hemisphere defy this trend, exhibiting
strong outgassing of natural CO2. This outgassing nearly cancels the
large uptake of anthropogenic CO2 in this region, leading to a near
zero net contemporary flux. The contemporary air-sea fluxes from the inversion
agree reasonably well with flux estimates derived from ∆pCO2
observations, with the exception of the above subpolar regions, where our flux
estimates are three to five times smaller. When analyzed together with the
observed atmospheric CO2 gradients, our results support the
existence of a substantial sink for atmospheric CO2 in the northern
hemisphere terrestrial biosphere, and a terrestrial carbon loss in the tropics.
Author's Names: N. Gruber, S.E. Mikaloff-Fletcher, A.R. Jacobson, et al
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COMPARING THE LONG-TERM MEANS AND BIOGEOCHEMICAL INTERPRETATION OF INTERANNUAL CARBON EXCHANGE ...
Description:
This presentation will interpret results from the
TransCom 3 interannual time dependent inversion. First, the long-term mean
carbon exchange will be compared across the three different TransCom 3
inversion levels: the annual mean, seasonal, and interannual control
experiments. We will highlight the agreement among these experiments in spite
of the differing degrees of freedom, and the differing CO2 observing
networks employed. Comparison will be made to independent decadal estimates of
land and ocean carbon uptake and will include the sensitivity to different CO2
networks. We will also interpret the model mean interannual carbon fluxes as
they relate to key indices of climate variability. In particular, correlation
to the El Niño/Southern Oscillation index will be made
suggesting a propagation carbon flux anomalies from the tropics to the extra
tropics following the peak of the ENSO
warm phase in the tropical Pacific ocean.
These correlations will be explained via anomalies in temperature and
precipitation from NCEP reanalysis.
Author's Names: K.R. Gurney
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SEPARATING THE NATURAL AND AIR-SEA FLUX OF CO2: THE INDIAN OCEAN
Description: We estimate the
natural and anthropogenic components of the air-sea flux of CO2 in
the Indian Ocean. The increase in atmospheric CO2
driven by human activity has caused the air-sea CO2 flux, to
increase significantly over the industrial era. We estimate the flux in the
year 1780 to be approximately 0.2Gt/yr, increasing by 0.26Gt/yr to 0.5Gt/yr in
2000. The estimate of the natural (preindustrial) flux is highly sensitive to
uncertainties in modern-day CO2 disequilibrium measurements. By
contrast, the estimate of the anthropogenic flux is only weakly sensitive to
these measurements. Our anthropogenic estimate is smaller than other studies
due to the removal in our methodology of the widely made weak-mixing and
constant-disequilibrium assumptions, both of which cause positive bias.
Author's Names: T.M. Hall and F. W. Primeau
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