USING INVERSE MODELLING TO INVESTIGATE POTENTIAL IR MEASUREMENT STRATEGIES FOR CONSTRAINING ...
Description:
CO2
and methane are important greenhouse gases, both contributing in increasing
amounts towards positive radiative forcing. It is hence important to gain
maximum understanding of the carbon cycle in the atmosphere, and the scale of
carbon trace gas sources and sinks, not only globally but also on a more
regional level. The Orbiting Carbon Observatory (OCO) satellite, scheduled for
launch in 2008, is designed for dedicated global mapping of CO2. In
order to investigate the usefulness of a variety of methods, including
retrievals from satellite mapping, some preliminary inverse modelling using a
Bayesian synthesis technique is performed using pseudodata generated to
represent possible future measurement regimes. This study will focus on the
ability of in-situ measurements within Australia to reduce the
uncertainties in Australian continental CO2 flux estimates. The
specific measurements investigated include a Ghan railway transect between
Adelaide (34.9°S, 138.6°E) and
Darwin (12.5°S, 130.9°E), and a number of continuous permanent sites. The
reduction in flux uncertainties from additional measurements compared to a
background inversion is examined, from which it is concluded that measuring on
the Ghan railway is potentially worthwhile for reducing uncertainties
associated with flux estimates.
Author's Names: N.M. Deutscher, R.M. Law, D.W.T. Griffith, and G.W. Bryant
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PRECISION REQUIREMENTS FOR SPACE-BASED XCO2 DATA
Description:
The Orbiting Carbon
Observatory (OCO) mission will deliver space-based observations of atmospheric
CO2 with the potential to resolve many of the uncertainties in the
spatial and temporal variability of carbon sources and sinks. Our assessments of the measurement
requirements for space-based remote sensing of atmospheric CO2 conclude
that the data must support retrievals of the column-averaged CO2 dry
air mole fraction, XCO2,
with precisions of 3 to 4 ppm to resolve the annually averaged gradients between the Northern and Southern hemispheres, but higher
precision (1 to 2 ppm) will be needed to resolve East-West gradients and
questions like the location and spatial extent of the Northern Hemisphere
terrestrial carbon sink. These
conclusions are derived from the results
of observational system simulation experiments (OSSEs) and synthesis inversion
models [Rayner and O’Brien, 2001; O’Brien and Rayner, 2002; Rayner et al., 2002]. The XCO2 precision
requirements also considered the OCO mission design, the amplitude of XCO2 spatial and temporal gradients, and the relationship between XCO2 data
precision and regional scale surface CO2 flux uncertainties inferred
from XCO2 data.
Author's Names: C. E. Miller, D. Crisp, P. L. DeCola, S. C. Olsen, et al
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Added on: 02-Aug-2005 Downloads: 33
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VARIATIONAL DATA ASSIMILATION OF HIGH DENSITY ATMOSPHERIC CO2 DATA:...
Description: High-frequency atmospheric CO2 measurements
should become increasingly available by the end of this decade from a variety
of sources, including low-Earth orbiting satellites. If of sufficient accuracy,
these should allow the functioning of the global carbon cycle to be monitored
at fine time/space resolutions using atmospheric transport inversions. Since
traditional direct inversion methods (e.g., Bayesian synthesis) become
computationally infeasible at these resolutions, we use an approximate method,
variational data assimilation, to estimate surface CO2 fluxes at
spatial resolutions ranging from 10x10 degrees to 1x1 degrees and at time
resolutions ranging from 2 weeks to 1 hour. We assess its performance using simulated
data, including the effects of realistic transport and data errors.
Author's Names: D.F. Baker, S. Doney, and D. Schimel
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Added on: 25-Jul-2005 Downloads: 34
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A FRAMEWORK FOR INTEGRATED GLOBAL ATMOSPHERIC CARBON OBSERVATIONS: IGCO AND IGACO
Description:
A
major challenge in reaching a better understanding of global change is the
integration of global carbon observations at different scales, made in the
atmosphere, ocean and terrestrial domains.
This is essential to optimize efforts supporting national, regional and
international policy related to the global carbon cycle. The partners of the Integrated Global
Observing Strategy (IGOS-P) representing all players in carbon cycle research
and monitoring recognised this and produced, with the help of an international
panels of experts, published theme reports on the Carbon Cycle (IGCO) and on
Atmospheric Chemistry (IGACO). These
themes contain recommendations on how to more effectively coordinate and fill
gaps in global Earth observations.
Author's Names: P. Ciais, L. Barrie and R. Dargaville
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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), OrlĂ©ans (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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Added on: 03-Aug-2005 Downloads: 34
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A HINDCAST OF SURFACE OCEAN PCO2 AND AIR-SEA CO2 FLUX PRODUCED BY A DATA-ASSIMILATING OGCM ...
Description:
The primary aim of the Centre for
Observation of Air-sea Interactions and Fluxes (CASIX) is to estimate
accurately the air-sea fluxes of CO2. Under CASIX, a high resolution
ocean general circulation model, coupled to an ocean biogeochemistry model, has
been used to provide estimates of surface ocean pCO2 and air-sea
fluxes of CO2 for the year 2003. An initial global simulation was
run at 1 degree horizontal resolution, providing boundary conditions for a
limited area North Atlantic model at 1/3
degree resolution. Observed temperature and salinity data were assimilated into
the model. Temporal variability in the resulting pCO2 fields are
compared to observations, and the primary production and pCO2 results
of the two different resolution runs are compared.
Author's Names: S.K.Liddicoat, R.M.Barciela, J.C.P. Hemmings, et al
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TOWARDS A NEW ISOPYCNIC OCEAN CARBON CYCLE MODEL
Description: Numerical
ocean carbon cycle models are the primary tools to predict the ocean's response
to increasing atmospheric CO2 concentration. So far most of these
have been based of physical components with geometric vertical levels. While
permitting an accurate computation of the horizontal pressure gradient driving
geostrophic flow, vertical discretization on z-levels leads to spurious
diapycnal mixing and upwelling. Isopycnic ocean models have an advantage over
those with geometric vertical layers in that their vertical coordinate mimics
the real structure of the water column as stratified layers of constant
density, and thus avoid artificial mixing and advection in the ocean interior.
Their disadvantages include the problem of massless layers, the necessity to
add a mixed layer model to adequately represent surface processes, and the
induction of a horizontal pressure gradient error by the sloping density
surfaces. Models with different vertical schemes thus complement each other and
can be used as one basis for an uncertainty assessment.
Author's Names: K.M. Assmann, C. Heinze, H. Drange, M. Bentsen, and K. Lygre
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DETERMINING CO2 FLUX COMPONENTS IN THE DENVER URBAN ECOSYSTEM
Description: Within urban ecosystems are strong anthropogenic
emissions of CO2 as well as significant CO2 sinks
associated with vegetation. CO2 profiles and net flux of CO2
(NEE) over Denver
was measured over a multi-year period and compared with certain component
fluxes (soil surface net flux, and emissions from fossil fuel combustion). CO2
concentration and NEE typically exhibits a diurnal trend, apparently due to
emissions from transportation and sequestration by vegetation.
Author's Names: D. E. Anderson and T. Thienelt
Filesize: 22.21 Kb
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THE IMPACT OF TRANSPORT AND ESTIMATION ERRORS ON THE SIGNIFICANCE OF INTERANNUAL CO2 FLUX...
Description: Transport-based
inversions of atmospheric CO2 concentration measurements have been
used by several groups [e.g., Bousquet, et al.,
2000; Rödenbeck, et al., 2003; Baker, et al., 2005] to estimate monthly regional CO2
fluxes from the 1980s to the present.
When compared at the scale of broad latitude bands, the inter-annual
variability (IAV) of these results is broadly consistent. This agreement breaks down, however, when the
fluxes are partitioned regionally inside these latitude bands, or even into
global land/ocean totals. We show here that this disagreement can largely be
explained by random estimation errors and transport model errors affecting the
estimates.
Author's Names: D.F. Baker, R. Law, and K.R. Gurney
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A REGIONAL-SCALE ANALYSIS OF THE ANTHROPOGENIC CONTRIBUTIONS TO CO2 IN THE MIDWEST: ...
Description:
Atmospheric observations obtained during intensive
field experiments are used to characterize regional sources and test data
assimilation techniques. In this study, the STEM-2K1
(Sulfur Transport Eulerian Model, version 2K1) and its adjoint model are applied
to the analysis of observations from aircraft platforms made during the summer
2004 ICARTT (International Consortium for Atmospheric Research on Transport)
experiment. Observed ratios between CO2 and tracers and model
derived airmass markers are used to identify emission signatures, indicating
the influence of different sources. Model derived influence functions along
with assimilated transport model results of anthropogenic tracers are used to
characterize the anthropogenic CO2 emissions in the Midwest during the summer 2004 period. This analysis
gives an initial look at the Midwest domain
which is the focus of the expansion of NOAA Climate Monitoring and Diagnostic
Laboratory’s tall tower observation network and the upcoming Mid-Continent NACP
Intensive Campaign.
Author's Names: J.E. Campbell, C.O. Stanier, G.R. Carmichael, et al
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Added on: 27-Jul-2005 Downloads: 39
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