Quantifying the uptake of anthropogenic carbon by the oceans is a crucial component of understanding the global carbon cycle. Accordingly there has been considerable research in the area, and recently global estimates of the inventory and decadal uptake of anthropogenic carbon have been made using carbon measurements [Sabine et al., 2004] and CFC measurements [McNeil et al., 2003].  However, these methods introduce several assumptions that may introduce systematic biases.  In particular, both methods assume that mixing plays a negligible role in the transport.  Here we estimate the ocean uptake, inventory, and distribution of anthropogenic carbon (C_ant) in the oceans using the transit-time distribution (TTD) method (see Hall et al. 2004, Waugh et al. 2004), which avoids the assumption of weak mixing.

CO₂ emissions from fossil-fuel combustion can be estimated at the state or monthly level even when full data on fuel combustion are not available. Our hypothesis is that a representative proxy can accurately estimate the pattern of CO₂ emissions if a sufficient fraction of the total can be represented, even if the dataset used does not cover all energy consumption sectors. Our approach employs monthly sales data for each state from the U.S. Department of Energy’s Energy Information Administration (EIA). This is used to estimate the relative proportions of solid, liquid and gaseous fossil fuels for each state for each month.

Over the last decade the TransCom group has coordinated a number of intercomparisons. The latest project focuses on the diurnal and synoptic behaviour of transport models.  The poster will describe the experiment, introduce the participating models and present a sample of preliminary results.

A discrepancy exists between current estimates of the Southern Ocean air-sea flux of CO₂.  The most recent estimate using a combination of direct and climatologically-derived pCO₂ measurements [Takahashi et al., 2002] (herein referred to as T02) suggests a Southern Ocean CO₂ sink that is nearly two times greater that that suggested from general circulation models, atmospheric inverse models [Gurney et al., 2002] and oceanic inverse models [Gloor et al., 2003]. Here we employ an independent method to estimate the Southern ocean air-sea flux of CO₂.  Our method exploits all available surface measurements for Dissolved Inorganic Carbon (DIC) and total alkalinity (ALK) from 1986 to 1996. We show that surface age-normalized DIC can be predicted to within ~8mmol/kg and ~10mmol/kg for ALK using standard hydrographic properties, independent of season.  The predictive equations are used in conjunction with World Ocean Atlas (2001) climatologies to estimate an annual cycle of DIC and ALK, while the pCO₂ distribution is calculated using standard carbonate chemistry.  For consistency we use the same gas transfer relationship and wind product from Takahashi et al, [2002] however, we include the effects of sea-ice. We estimate a Southern Ocean CO₂ sink (>40°S) of -0.19±0.26 Pg C for 1995. Our estimates are smaller than those estimated by Takahashi et al, [2002], but consistent with atmospheric / oceanic inverse methods, general circulation models and provides further evidence that the Southern Ocean CO₂ sink in relation to its oceanic surface area, is moderate on a global scale.

We will present our design of a new autonomous, inexpensive, and robust CO₂ analyzer (AIRCOA), a description of our quality control procedures, and data examples from ongoing deployments.  Our current AIRCOA units require less than $10K (USD) in components, show intercomparability better than 0.1 ppm during laboratory tests, and are designed to run autonomously for months at a time.

We present here a test of convection uncertainty within a single model framework driven by the same meteorological fields. Our primary goal is to explore to what extent do convection schemes impact atmospheric CO₂ distribution, by testing three referred cloud convection schemes ranging from a very simple to a relatively complex form [Table 1]. Our second goal is to examine the sensitivity of atmospheric CO₂ to its regional emission/sink uncertainty [Fig. 1] constrained by IPCC 2001 at a “fixed” convection scheme to clarify the pros and cons of the convection schemes.

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.

We are establishing a continuous CO₂ observing network in the Rocky Mountains, building on technological and modeling advances made during the Carbon in the Mountains Experiment (CME), to improve our understanding of regional carbon fluxes and to fill key gaps in the North American Carbon Program (NACP). We will present a description of the Rocky RACCOON network and early results from the first three sites.

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.