We present 16 months of semi-continuous Ar/N₂ data measured at the Scripps Pier in La Jolla, CA. The concentration of atmospheric Ar/N₂ depends on air-sea heat flux. As the ocean takes up heat, both argon and nitrogen are degassed to the atmosphere; as the ocean cools, they are taken up. This record is the beginning of a long-term monitoring program that will parallel the O₂/N₂ and CO₂ measurement programs at Scripps and may help resolve the oceanic contribution to atmospheric CO₂ variability.

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.

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.

The role of the Southern Ocean as a source or a sink for CO₂ in the modern ocean is heavily disputed, its interannual variability is unknown, and its control on atmospheric CO₂ during glaciations is suspected but still not understood nor quantified.  We estimate the variability of the air-sea CO₂ fluxes in the Southern Ocean for the 1992-2003 period using the spatio-temporal distribution of atmospheric CO₂ measurements from 12 stations in the Southern Ocean and 43 stations worldwide.  Our results show basin-scale variability of ±0.1 to 0.3 PgC/y that are related to physical variability in the Southern Ocean.

The coupled feedback processes of energy and carbon cycles are an essential mechanism for understanding global environmental change. We developed a simplified one-dimensional carbon and energy cycle coupled model to quantify the feedback processes between energy and carbon cycles. The model was calibrated to reproduce the historical variations in temperature and atmospheric CO₂ concentration. The model results of vertical ocean temperature profiles, and latitudinal NPP and NEP distributions were in good agreement with the observation data and terrestrial biosphere model results. The regional difference of terrestrial ecosystem response by climate feedback appeared in the middle and high latitudes. The north-south distribution is important to investigate the terrestrial ecosystem because the opposite response appeared in the middle and high latitude. The future change of carbon cycle and climate was also simulated up to the year 2100 based on the IPCC scenario. The atmospheric CO₂ concentration reaches 735 ppmv in 2100 and global average temperature increases 1.9 K for 2000-2100.

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.

In the present study atmospheric CO₂ retrievals based on Aqua satellite AIRS (Atmospheric Infrared Sounder) instrument observations are compared with forward model predictions. There is quite good agreement in seasonal cycles as well as North-South gradients when averaged over large scales. At smaller scales there are contrasts between upper troposphere CO₂ above continents versus oceans in the retrievals and there are signatures off Africa which seem likely artifacts caused by aerosols. As a consequence retrievals cannot be used at this stage to constrain surface sources and sinks without causing large biases. Interestingly there is good agreement in the shape of the N-S gradient at low-to-mid latitudes in the Northern hemisphere between simulations based on one transport model (LMDZ) and retrievals, but disagreement when comparing with simulations based on a second transport model (TM3). This raises questions about lower to upper troposphere transport and their representation in these models.

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.