Our understanding of biogeochemical and physical processes in the Southern Ocean, which are critically important to future anthropogenic CO₂ uptake and global climate, is limited by the sparse spatial and temporal coverage of existing oceanographic and atmospheric measurements. We will present high-precision horizontal atmospheric O₂ and CO₂ concentration gradients over the Southern Ocean from three independent observing networks. These measurements reveal that, relative to southern mid-latitudes and Antarctica, CO₂ concentrations over the Southern Ocean are high during winter and low during summer (Fig. 1). This suggests a seasonal variation between net CO₂ summertime uptake and wintertime release that is in disagreement with the T99 [Takahashi et al., 2002] dissolved pCO₂ climatology, which predicts year‑round CO₂ uptake, and with the OCMIP‑2 biological ocean general circulation models [BOGCMs, Doney et al., 2004], which either predict year-round CO₂ uptake or opposite seasonality with wintertime uptake and summertime release.

The present study made an attempt to analyse the extent of natural and anthropogenic carbon in the atmosphere and oceans particularly with reference to Indian Ocean as major human clusters are responsible for climate change. The study also probes into the spatial patterns and temporal variation using the time series data collected from secondary sources.

Continuous atmospheric measurements from tall towers have the capability to bridge an observational gap between hemispheric and local scales. We present first results from measurements made at such a tower in Germany. We show anti-correlated O₂ and CO₂ high frequency temporal variations which are caused by regional land biotic and fossil fuel emissions. We also show correlated changes in CO₂ concentration with air mass back trajectories, for example showing elevated CO₂ from air masses derived from eastern Europe, and lower, “background” concentrations from air masses derived from the North Atlantic.

First atmospheric δO₂/N₂, CO₂ and δ¹³C flask measurements from vertical aircraft sampling in the lower troposphere above Griffin Forest (GRI), Perthshire, UK, (56°37’N, 3°47’W) and from ground based flask sampling at the high altitude site Jungfraujoch (JFJ), Switzerland (3580m above sea level (a.s.l.), 46°33’N, 7°59’E), and the mountain site Puy de Dôme (PUY), France (1480m a.s.l., 45°46’N, 2°58’E) are presented.

We present a statistical analysis of aircraft and surface measurements of the CO₂ mixing ratio over the US Rocky Mountains during 1993 – 2002 at latitudes close to that of the Issyk-Kul station in Kyrgyzstan. Average characteristics of the CO₂ mixing ratio and its annual variations show only small height variability in the troposphere over well mixed mountain regions. Comparison of Issyk-Kul optical data with US aircraft and surface measurements shows satisfactory agreement. Also some differences at low altitudes were obtained owing to possible regional differences between mountain regions of Central Asia and USA.

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. 

Tropical drought can significantly impact inter-annual variations in the terrestrial CO₂ fluxes. Concentrations and carbon isotope ratios of atmospheric CO₂ can help to quantify this impact, however, their use requires a model estimation of the terrestrial isotope disequilibirum, i.e. the difference between the isotopic signature of photosynthesis and respiration, which can only be achieved by accurately accounting for changes in relative contributions of C3 and C4 plants (C4 fraction) and physiological effects of root-zone water stress.

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.

We evaluate the impact on modeled atmospheric CO₂ concentrations of explicitly representing the tropospheric CO₂ source from reduced carbon oxidation. We also calculate the bias in inverse flux estimates that results from omitting this influence.