RECTIFIER EFFECT IN AN ATMOSPHERIC MODEL WITH DAILY BIOSPHERIC FLUXES
Description:
The synoptic scale atmosphere-biosphere interaction
can cause anomalies of ~10 ppm with length scale of ~1000 km in the monthly
averaged surface CO2 concentration. These anomalies may contribute
to the errors and uncertainties of CO2 inversion estimates.
Author's Names: M. Ishizawa, D. Chan, K. Higuchi, S. Maksyutov, 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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Added on: 03-Aug-2005 Downloads: 27
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PROMOTION EFFECTS OF FALLING DROPLETS ON CARBON DIOXIDE ABSORPTION ACROSS THE AIR-WATER INTERFACE
Description: The effect of
rainfall on mass transfer across the air-water interface was investigated
through the CO2 absorption experiments in a turbulent open-channel
flow with the free surface. The results show that the rainfall enhances both
the turbulent mixing near the free surface on the liquid side and the CO2
transfer across the interface. The mass transfer coefficient on the liquid side
is well correlated by both the mean vertical momentum flux of rainfall, M, and the mean kinetic energy of rain
droplets impinging on the unit area of the air-water interface, KEF. However, it was not concluded which
of M and KEF is a better parameter for expressing
the rainfall effects on the mass transfer. The comparison between the mass
transfer coefficient obtained in this study and that obtained in wind-driven
turbulence suggests that it is of great importance to consider the rainfall
effect on the CO2 exchange rate between the atmosphere and ocean in
precisely estimating the global carbon cycle in a climate model.
Author's Names: N. Takagaki1 and S. Komori
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Added on: 08-Aug-2005 Downloads: 30
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PROGRESSIVE DECREASE OF THE N. ATLANTIC MIDLATITUDE SINK FOR ATMOSPHERIC CO2
Description: We present monthly means of observations of sea
surface and atmospheric pCO2 and associated variables made on board
commercial vessels operating in the mid-latitude North Atlantic between the UK and the Caribbean.
The measurements were made using automated instrumentation in 1994 -1995, and
again from 2002 - present, allowing the study of changes which have taken place
over a large region of the North Atlantic over
almost a decade. Sea surface pCO2 has increased faster than atmospheric
pCO2 over the whole region, so that ΔpCO2 has decreased,
reducing the mid-latitude North Atlantic sink
from the atmosphere. The change in ΔpCO2 is largest in the north and
east, and smallest in the south and west of the region.
Author's Names: U. Schuster, and A.J. Watson
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Added on: 04-Aug-2005 Downloads: 19
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PRELIMINARY CONSTRAINTS ON FOSSIL-FUEL CO2: COMPARISON OF TRACERS 14CO2, CO AND SF6
Description: We use the
theoretically ideal tracer 14CO2 to estimate the fossil
fuel CO2 enhancement in boundary layer air at two sites in New
England and Colorado.
Improved D14C measurement
precision of 1.6-2.6‰ provides fossil fuel CO2detection capability
of 0.8-1.5 ppm. Using the tracers CO and SF6, we obtain two
additional independent estimates of the fossil fuel CO2 component,
and we assess the biases in these methods by comparison with the 14CO2-based
estimates. Large differences are observed between the SF6-based
estimates and those from the 14CO2 and CO methods. The
CO-based estimates show seasonally coherent biases, underestimating fossil fuel
CO2 in winter and overestimating in summer.
Author's Names: J.C. Turnbull, J.B. Miller, S.J. Lehman, R.J. Sparks, et al
Filesize: 92.02 Kb
Added on: 08-Aug-2005 Downloads: 22
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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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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
Filesize: 72.02 Kb
Added on: 29-Jul-2005 Downloads: 23
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PERFORMANCE ANALYSIS OF THE LOFLO CONTINUOUS CO2 ANALYSER: MONITORING OF BASELINE AND ...
Description: Results are presented
from recent evaluations of multiple “LoFlo” CO2 analysers. These
experiments were conducted at both an urban site (Aspendale, a suburb of Melbourne, Australia),
and the Cape Grim baseline site. Figure 1 shows the
preliminary results from an overlap experiment involving two LoFlo analysers (identified
here as LoFlo-2A, and LoFlo-2B, each one operating with its own suite of
calibration gases) measuring marine boundary layer air from a shared single air
intake at the Cape Grim Baseline Air Pollution Station, in northwest Tasmania,
during April/May 2005. The figure shows the differences between hourly CO2
values from the two analysers, during those periods when baseline conditions
were experienced. The seven high pressure, CO2-in-dry air
calibration standards used for the LoFlo-2B system have been calibrated at the Carbon
Cycle Gases Group (CCGG), United States National Oceanic and Atmospheric
Administration (NOAA), Climate Monitoring and Diagnostics Laboratory (CMDL),
designated by the World Meteorological Organization (WMO) as the CO2
Central Calibration Laboratory.
Author's Names: M.V. van der Schoot, L.P. Steele, R.J. Francey, et al
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pCO2 IN SUBANTARCTIC SURFACE WATER: A TIME SERIES STUDY
Description:
A time series transect has been established in
subantarctic surface water off the south east coast of New Zealand. The 60 km long transect extends from the
coast (45-46.20oS 170-43.20oE) to a station at 45-50.00oS
171-30.00oE. and sea surface temperature, salinity and pCO2
have been measured bi-monthly since 1998 . SST, pCO2 and pH of the
subantarctic surface water show seasonal cycles that can be fitted with simple
harmonic curves. Temperature has a mean
value of 10.4oC, with an amplitude of 2.1oC, the maximum
occurring in late summer. pCO2
has a mean value of 360 matm, an amplitude of 10 matm, the maximum occurring in early
spring. The phase of the pCO2
and temperature curves are offset by 158 days, indicating that change in sea
water temperature is not the major factor affecting pCO2 in this
area. The relative effects of
temperature, biological utilization and air-sea gas exchange on the seasonal
change in pCO2 are determined using a simple model. The model results reproduce the timing of the
observed pCO2, however the amplitude of the changes is not well
reproduced.
Author's Names: K.I. Currie and M.R. Reid
Filesize: 36.14 Kb
Added on: 28-Jul-2005 Downloads: 22
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PACIFIC DOMINANCE TO GLOBAL AIR-SEA CO2 FLUX VARIABILITY: A NOVEL ATMOSPHERIC INVERSION AGREES ...
Description:
We
address an ongoing debate regarding the geographic distribution of interannual
variability in ocean - atmosphere carbon exchange. We find that, for 1983-1998,
both novel high-resolution atmospheric inversion calculations and global ocean
biogeochemical models place the primary source of global CO2 air-sea
flux variability in the Pacific Ocean. In ocean biogeochemical models, this
variability is clearly associated with the El Niño / Southern Oscillation
cycle. Both inversion and models indicate that the Southern Ocean is the
second-largest source of air-sea CO2 flux variability, and that
variability is small throughout the Atlantic, including the North Atlantic, in
contrast to previous studies.
Author's Names: G.A. McKinley, C. Rödenbeck, M. Gloor, et al
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