VARIATIONS IN ATMOSPHERIC O2 AND CO2 IN THE SOUTHERN OCEAN REGION FROM CONTINUOUS SHIP-BASED ...
Description:
Variations in atmospheric oxygen (O2) are a
sensitive indicator of biogeochemical processes involved in the global carbon
cycle. To improve our understanding of
these processes, we developed a system for continuous high precision
measurements of atmospheric O2 and CO2 that is suitable
for shipboard use. This system was
employed on two voyages in the Western Pacific sector of the Southern Ocean, in
February 2003 and April 2004. Elevated O2
concentrations were observed south of New Zealand and across the Chatham
Rise suggesting that these regions of ocean are outgassing O2 in
late summer to autumn.
Author's Names: R. L. Thompson, A. C. Manning, D. C. Lowe, and C. Rödenbeck
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Added on: 08-Aug-2005 Downloads: 23
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VARIATIONS OF OCEANIC PCO2 AND AIR-SEA CO2 FLUX IN THE GREENLAND SEA AND THE BARENTS SEA
Description:
In order to elucidate seasonal
and interannual variations of oceanic CO2 uptake in the Greenland
Sea and the Barents Sea, partial pressures of
CO2 in the surface ocean (pCO2sea)
were measured from 1992 to 2001. The values of pCO2sea
were lower than the partial CO2 pressures in the atmosphere (pCO2air) throughout the year, and the
annual net air-sea CO2 fluxes in the Greenland Sea and the Barents Sea were evaluated to be 52 ± 31 and 46 ± 27 gC m-2
yr-1, respectively, yielding a total oceanic CO2 uptake of
0.050 ± 0.030 GtC yr-1. We also found that the annual mean CO2
uptake was positively correlated with the North Atlantic Oscillation Index
(NAOI) via wind strength, but was negatively correlated with DpCO2 (pCO2air-pCO2sea) and the sea ice coverage. The
results also indicate that the wind speed and sea ice coverage play a major
role in determining the interannual variation of CO2 uptake, with DpCO2 playing a minor role.
Author's Names: S. Nakaoka, S. Aoki, T. Nakazawa, G. Hashida, et al
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Added on: 03-Aug-2005 Downloads: 19
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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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Added on: 03-Aug-2005 Downloads: 33
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VERTICAL PROFILES OF THE O2 N2 RATIO IN THE STRATOSPHERE OVER JAPAN AND ANTARCTICA
Description: To
examine vertical distributions of the O2/N2 ratio in the stratosphere, air
samples were collected using a cryogenic sampler over Sanriku,
Japan and Syowa, Antarctica. It
was clearly seen that d(O2/N2), as well as
simultaneously measured d15N of N2 and d18O of O2, decreased
gradually with increasing height in the stratosphere. The observed profiles of
stratospheric ï€ d15N and d18O were in good agreement
with those calculated using a steady state
1-dimensional eddy-diffusion/molecular-diffusion model suggesting that the
upward decrease of stratospheric d(O2/N2)
is caused by O2 and N2 molecules fractionated differently
by gravity. The stratospheric d(O2/N2) corrected for the
gravitational separation indicated that the average value at heights above
20-25 km over Sanriku was always higher than
the upper tropospheric d(O2/N2)
value over Japan
at the corresponding time, and that it has decreased secularly, as was found in
the troposphere.
Author's Names: Shigeyuki Ishidoya, Satoshi Sugawara, Gen Hashida, et al
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Added on: 29-Jul-2005 Downloads: 28
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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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WHAT CAN WE LEARN FROM INTENSIVE ATMOSPHERIC SAMPLING FIELD PROGRAMS?
Description:
Intensive atmospheric
sampling field programs are envisioned as a key component of integrated
research programs such as the North American Carbon Program (NACP) [Sarmiento and Wofsy,
1999; Wofsy and Harriss, 2002]. The intensive
sampling provides unique information about the spatial distribution of CO2
as well as imposes tight constraints on regional budgets that are difficult to
obtain from other means. We summarize what we have learned from the numerous
COBRA (CO2 Budget and Rectification Airborne study) experiments [Gerbig et al.,
2003a] that have taken place in 2000, 2003, and 2004. We present the observed spatial variability
of CO2 [Gerbig et al., 2003a; Lin et al.,
2004a] and regional budgets derived from regional air
parcel-following experiments [Lin et al., 2004b]. These
observations are also used as a critical testbed for modeling frameworks [Gerbig et al.,
2003b]. We draw conclusions about ways to maximize the value
of intensive atmospheric sampling experiments and the role that such
experiments should play within programs like the NACP.
Author's Names: J.C. Lin, C. Gerbig, S.C. Wofsy, B.C. Daube, et al
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Added on: 01-Aug-2005 Downloads: 123
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