The WLEF TV tower in northern Wisconsin is instrumented to take continuous measurements of CO₂ mixing ratio at 6 levels from 11 to 396m. During the spring and summer of 2004 additional CO₂ measurements were deployed on five 76 m communication towers forming a ring around the WLEF tower with a 100-150 km radius.

The CROZEX cruises (November 2004 to January 2005) had the objective to test whether natural iron fertilisation from the Crozet plateau promotes algal blooms. Results from the cruises show that algal blooms created an oceanic CO₂ sink downstream of the Crozet plateau. Vertical advection of water into the mixed layer occurred close to two islands on the plateau. Data from 18 cruises between 1991 and 2002 are used to quantify the seasonal variability of surface pCO₂ and CO₂ air-sea exchange in the region.

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.

We present a new version of the global atmospheric tracer transport model driven by analyzed meteorology with diurnally varying mixing in the boundary layer capable of running globally at resolutions up to quarter degree longitude-latitude or higher. The impact of the higher resolution model can be visible in resolving city plumes, airmass boundaries, diurnal cycle, fronts and synoptic scale events often observed in continuous CO₂ monitoring site data.

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.

We have developed a new data screening technique using an atmospheric transport model and an inverse model. Using this technique, we can use original (not smoothed) observational data for the inversion method. This means that we can enlarge the number of observational data for inversion method and we can estimate carbon dioxide (CO₂) flux history consistently in long period in accordance with the number of the observational sites.  

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.