TOP-DOWN REGIONAL CO2 FLUXES FOR NORTH AMERICA ESTIMATED FROM NOAA-CMDL CO2 OBSERVATIONS
Description:
We present an analysis of terrestrial net CO2 fluxes from North America for the period 2000-2004. These fluxes
consist of hourly maps at ~70km×100km resolution that are consistent with
observed atmospheric CO2 mixing ratios, as well as with varying
climatic conditions across different ecosystems as observed from space. The
flux maps are created in a newly developed ensemble data assimilation system
that consists of the atmospheric Transport Model v5 (TM5), the Vegetation
Photosynthesis Respiration Model (VPRM), and an efficient Bayesian
least-squares algorithm to optimize the fluxes from different biomes in VPRM
against CO2 mixing ratios from the NOAA-CMDL
observing network. The stochastic nature of the ensemble data assimilation
system allows us to consistently include uncertainty on net CO2 fluxes from the neighboring oceans and more distant continents
in the flux estimates for North America.
Author's Names: Wouter Peters, Lori Bruhwiler, John Miller, et al
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CARBON CYCLE INVERSION VALIDATION USING PROFILE AND OTHER NON-SURFACE OBSERVATIONAL DATA
Description:
We present preliminary results of a
modeling experiment that compares observed vertical profiles of CO2
with those generated by an atmospheric transport model (ATM). The ATM is driven
by CO2 flux fields generated from the inversion of monthly averaged
CO2 surface data (GLOBALVIEW). We note large differences between the
best fit to the observations produced in the inversion and the same quantity
simulated by the forward model. This difference arises from the nonlinearity of
the advection scheme used in the transport model. When comparing with vertical
profiles, we note that much of the difference between simulated and observed
concentration has the same structure as the impact of this nonlinearity.
Inversion schemes must therefore take nonlinearity into account. Despite these
differences, the profiles are able to distinguish among inversions that fit
subsets of the surface data, suggesting they are a useful validation dataset.
Author's Names: C.A. Pickett–Heaps, P.J. Rayner, R.M. Law, P. Peylin, et al
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FIRST RESULTS FROM A 300 M TOWER ATMOSPHERIC MEASUREMENT STATION FOR GREENHOUSE ...
Description:
CHIOTTO – Continuous
HIgh-precisiOn Tall Tower Observations of greenhouse gases – is a European
Union-funded project which has as objective to build an
infrastructure for the continuous monitoring of greenhouse
gas concentrations across Europe above the surface layer using
tall towers (~300m height). For this purpose
a
new analysis system
for continuous atmospheric measurements was
built and tested at Max Planck Institute for Biogeochemistry, Jena,
Germany and was recently installed
at a 300 m tower
close to Bialystok, Poland (Lat 53°14'N, Long 23°01'E, Alt 180m),
as part of the “CHIOTTO”
tall tower network.
Since July
2005 this
system is measuring
quasi-continuously the atmospheric concentration of CO2,
CH4,
CO, N2O,
SF6
and the O2/N2
ratio as well as meteorological
parameters (atmospheric pressure,
temperature, humidity; wind speed and direction) from 5
heights on the tower ranging from 5 to 300 m.
The measurement devices
are: an
Oxzilla O2 fuel cell analyzer, a
LiCor 7000
NDIR CO2 analyzer, an
Agilent
gas chromatograph (GC) with flame ionization
detector (FID) and electronic
capture detector (ECD) for CH4, CO, N2O, SF6. The
challenge was to build a reliable automatic system which can run continuously
with very little maintenance and to fulfill at the
same time the high precision requirements for all the measured species prescribed
by the CHIOTTO project goals. The high
temporal resolution achieved will
capture
short
term events and diurnal variability. In addition, the
system is planned to run for at
least several years in order to observe long-term trends
as well.
We describe
the technical setup of the measurement system, the region of
influence of the station and present the first months of
data if available: correlations between species,
observed short term variability patterns and their relation to meteorology and
air parcel paths.
Author's Names: E.Popa, A.C.Manning, M.Gloor, U.Schultz, et al
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STUDY OF ATMOSPHERIC CO2 REGIONAL VARIABILITY OVER EUROPE THROUGH THE ANALYSIS OF INTENSIVE ...
Description: We carried out airborne
campaigns over Europe in order to analyze
atmospheric CO2 variability at the regional scale. Data reveal a
higher standard variation in the planetary boundary layer (PBL) against a lower
one in the free troposphere (FT), where the air is more well mixed. Ground data
generally agree well with airborne measurements when done in the FT, but not in
the PBL where they are exposed to local disturbances. Ground stations located
in the FT are shown to be representative of a regional scale while PBL
observatories provide only locally representative measurements.
Author's Names: I. Xueref, M. Ramonet, P.Nedelec, J.A.Morgui, et al
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VERTICAL AIRCRAFT PROFILES OVER EUROPE
Description:
Regular vertical profiles over Europe were set up in
2001 as part of the AEROCARB and Carboeurope-IP projects at five locations:
Griffin (56°36'N, 3°47'W, Scotland), Orléans (47°50'N, 2°30'E, France),
Schauinsland (47°55'N, 7°55'E, Germany), Hegyhatsal (46°57'N, 16°39'E, Hungary),
and Bialystok (53.20°N, 22.75°E, Poland). The objective of the program is to
measure CO2, CH4, N2O, SF6, CO, 13C
and 18O in CO2 vertical profiles at a bi-weekly frequency
using air samples taken up at several levels from 100m up to 3000 m above the
ground surface. One liter flasks are sampled on board small aircraft using a
standardised protocol. The samples are analysed at three laboratories (LSCE,
MPI-BGC, IUP-UHEI) which are
linked through regular intercomparison exercises. We have characterised for
each site the CO2 seasonal cycles within the atmospheric boundary
layer (ABL: 14 to 20 ppm) and the
free troposphere (FT: 10 to 13 ppm). From these signals we have calculated the
difference between ABL and FT,
known as the CO2 'jump', which will be compared to the simulations
from atmospheric transport models. We have also calculated the offset between
each airborne sampling site and the time series from Mace Head observatory,
used as a maritime reference. For CO2, the wintertime offsets at the
lowest level of the average vertical profiles are ranging from 0 ppm in Scotland
up to 10 ppm in all continental sites. Depending of the site the positive
offset due to emissions from anthropogenic and biospheric processes may extend
up to 300 to 1500 m agl. In summertime we observe a negative gradient in most
of the sites with a typical decrease of 5 ppm between 2000m and 100m agl. The
average vertical gradients will be compared to the ouput of atmospheric models,
and will be analysed with regards to the other trace gas (CO, CH4,
and CO2 isotopes).
Author's Names: M. Ramonet, L.Haszpra, K. Katrynski, I. Levin, et al
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A BAYESIAN SYNTHESIS INVERSION OF CARBON CYCLE OBSERVATIONS: HOW CAN OBSERVATIONS REDUCE ...
Description: Current
predictions of future CO2 sink strength vary widely as a result of
different model representations of the carbon cycle. A sound characterization of these prediction
uncertainties is crucial for the design of economically efficient carbon
management strategies. We use a mechanistically sound and statistically
tractable model of the global carbon cycle to (1) assimilate historical observations
of atmospheric CO2 concentrations and oceanic CO2 fluxes,
(ii) derive probabilistic predictions of future CO2 concentrations
and fluxes, and (iii) compare the utility of terrestrial and oceanic
observations to constrain predictive uncertainties. We found that terrestrial and oceanic flux
observations have nearly equal ability to constrain these uncertainties, if
terrestrial observations include both net primary productivity (NPP) and
respiration. Model predictions are
dependent on the choice of historical land use emissions dataset. The probability density function (PDFs) of
model parameter estimates are not normally distributed, and neglecting
autocorrelation in the CO2 concentration signal during model
calibration causes overconfident results.
Author's Names: D.M. Ricciuto, K. Keller, and K.J. Davis
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ESTIMATES OF ATMOSPHERIC POTENTIAL OXYGEN FLUXES BASED ON O2 N2 AND CO2 CONCENTRATION ...
Description: The global biogeochemical cycle of oxygen
is closely linked to that of carbon dioxide, because key biological processes,
as well as fossil fuel burning, occur with specific stochiometric ratios. In
the ocean, however, several processes – carbonate chemistry (buffer effect),
physical transport (dilution), and warming/cooling (solubility changes) –
decouple O2 and CO2 exchanges. Based on a decade of
atmospheric O2/N2 and CO2 data, we estimated
spatial and temporal patterns of oceanic APO fluxes, using an inversion of
atmospheric transport. Seasonal and interannual variations are interpreted in
the light of climate variables.
Author's Names: C. Rodenbeck, C. Le Quere, R.F. Keeling, et al
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RECENT CO2 FLUX VARIABILITY ESTIMATED FROM ATMOSPHERIC MIXING RATIO MEASUREMENTS – AN UPDATE
Description:
Regular multi-year
measurements of atmospheric CO2 mixing ratios at a network of sites
(Fig. 1) give quantitative spatial and temporal information on surface sources
and sinks [e.g., Conway et al., 1994]. Using a
global atmospheric tracer transport model in a high-resolution (daily, 4x5
degree pixels) inversion setup, we estimate surface-atmosphere CO2 fluxes
that give the best match between modelled and observed CO2 concentrations.
Building on an earlier study [Rödenbeck et al.,
2003], this contribution (1) presents new CO2 flux estimates using
methodological developments, and (2) provides an update on interannual fluxes over
the most recent anomalous time period 2002-2003.
Author's Names: C. Rödenbeck, T.J. Conway, R. Langenfelds, et al
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DECADAL CHANGES IN OCEAN CARBON UPTAKE
Description:
There
is growing evidence that the rate of anthropogenic CO2 uptake in the
ocean is changing over time. Several programs are poised to assess current and
future ocean CO2 uptake rates, but there are issues with how to
extrapolate these measurements to decadal-scale changes over entire ocean
basins. One possibility is to exploit the growing network of ARGO floats that
are collecting profiles throughout the global oceans. We explore the viability
of this approach and make recommendations for how the ARGO network might be
made more useful for biogeochemical applications.
Author's Names: C.L. Sabine, R.A. Feely, G.C. Johnson, R. Wanninkhof, et al
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OVERVIEW OF OCO VALIDATION
Description:
The
Orbiting Carbon Observatory is a NASA ESSP mission that is scheduled for launch
in September 2008 [Crisp et al., 2004]. The space-based observatory
will sample the dry air, column averaged mole fraction of CO2 (XCO2) based on analysis of
reflected solar radiation, between ~0.78 and 2.0 microns, acquired by three
grating spectrometers. To fulfill the mission’s science objectives, the OCO
validation activities are focused on demonstrating that space-based retrievals
of XCO2 have random
errors no larger than 0.3% (1 ppm) over a network of ground based validation
sites on monthly time scales [Miller et al.,
2005]. Furthermore, space-based retrievals of XCO2
will be compared to measurements from this network of ground-based stations to
detect and mitigate geographically coherent biases on regional to continental
scales. We describe plans and progress to date of the OCO validation program,
which consists primarily of a series of ground-based, Fourier Transform
Spectrometers (FTS), that measure XCO2 in the same spectral
regions as the space-based spectrometers.
Author's Names: R. J. Salawitch, P. O. Wennberg, G. C. Toon, et al
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