Systematic measurements of the CO₂ concentration and its carbon isotopic ratio (d¹³C) have been carried out at 7 locations in China since March or July 2003. Seasonal cycles of the CO₂ concentration and d¹³C were clearly observable, especially at Longfengshan, Shangdianzi and Fukang. The d¹³C value of source producing the seasonal CO₂ cycle at each site, d_S, was estimated from the observed CO₂ and d¹³C seasonal cycles.  The average value of d_S derived for the 6 sites was calculated to be -25.6 (±1.8) ‰, which is larger than those observed at mid-latitudes in the western Pacific region, probably due to smaller discrimination of ¹³C by C₄ plants in the continent of China. 

The carbon dioxide transport at the Niwot Ridge AmeriFlux site was investigated in both gravity and streamline coordinates. For this forested site with a 6% slope, both nighttime drainage flow and daytime upslope flow played important roles in the CO₂ budget. Both the CO₂ respiration at night and the CO₂ uptake during the day are underestimated if the horizontal transport of CO₂ is not monitored; and the two components may not cancel out.

The results of an optimisation of inter-annual methane sources and sinks calculated by inversion of atmospheric observations are presented and analysed for the 1984-2003 period. We focus our presentation on sources trend and inter-annual variability. Comparisons with bottom-up estimates are presented for biomass burning and wetlands emissions (only in the poster).

Results of airborne CO₂ and CO observations from the NSF/NCAR C-130 platform during the Gulf of Tehuantepec Experiment (GOTEX 2004) and the Airborne component of the Carbon in the Mountains Experiment (ACME 2004) will be presented. A modified commercial vacuum ultraviolet fluorescence instrument monitored CO mixing ratios. CO measurements were used to help identify air masses recently influenced by combustion emissions. CO₂ mixing ratios were measured using a pressure- and temperature-controlled LI-COR 6252 analyzer.  Control of time response allowed operation of the CO₂ instrument in two modes for application to either low altitude eddy covariance or higher altitude mixing ratio measurements. Performance will be assessed, including accuracy estimates derived from intercomparison activities.

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 (45-46.20^oS 170-43.20^oE) to a station at 45-50.00^oS 171-30.00^oE. 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 10.4^oC, with an amplitude of 2.1^oC, 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.

We have developed a carbon flux inversion method for using a mesoscale meteorological model (CSU-RAMS) within a Maximum Likelihood Ensemble Filter (MLEF, Zupanski 2005; Zupanski and Zupanski 2005). The MLEF is a variant of the Ensemble Kalman Filter, and is used to optimize model state variables and parameters based on continuous observations of CO₂ mixing ratio. The method does not require the development of a model adjoint, but rather relies on transformation of variables to efficiently obtain estimates of fluxes with uncertainties and dynamical model error from an ensemble of forward model simulations. We demonstrate this method using a mesoscale simulation of weather, transport, and the surface carbon budget over the continental USA during the summer. The estimation procedure decomposes the total surface flux into photosynthesis and respiration (which are assumed to be modeled correctly to first order), plus an unknown but time-invariant fractional error in each.  These residuals are estimated for each model grid cell over a moving window in time, allowing atmospheric observations to be integrated over sufficient time to obtain constraint. Model error can also be estimated by this procedure, and the method can be extended to larger domains and longer integrations.

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.

High-quality data of total inorganic carbon (TCO₂) and other oceanographic parameters have been acquired repeatedly between 1994 and 2003 along 137ºE (WOCE P9) in the western North Pacific. They indicate the significant increase in TCO₂, apparent oxygen utilization (AOU) and preformed TCO₂ in the water columns between 20ºN and 30ºN, in particular, in the North Pacific Subtropical Mode Water (NPSTMW). The increase in the preformed TCO₂ suggests the 0.9 to 1.1 mol m^-2 yr^-1 accumulation of the anthropogenic CO₂ in this region. However, the change in the preformed TCO₂ associated with the change in the formation region and/or advection of NPSTMW is also suggested.

The spatial and temporal variations of atmospheric CO₂ at 8-13 km from April 1993 to March 2005 were observed by measuring CO₂ concentrations in samples collected biweekly from a commercial airliner between Australia and Japan. The 12-year record between 30N and 30S revealed several characteristics for CO₂ interannual variabilities in the upper troposphere. The most significant year-to-year change was found in a large increase in the growth rate during 1997/98 and 2002/03 that were associated with the ENSO events. During these years, changes in north-to-south gradient of latitudinal distribution and seasonal cycle were observed compared to data during the normal years.

This paper presents estimates of the ¹³C Suess effect and anthropogenic carbon concentration increase in the Nordic Seas since 1981.