The Orbiting Carbon Observatory is a NASA ESSP mission that is scheduled for launch in September 2008 [Crisp et al., 2004]. The space-based observatory will sample the dry air, column averaged mole fraction of CO₂ (X_CO2) based on analysis of reflected solar radiation, between ~0.78 and 2.0 microns, acquired by three grating spectrometers. To fulfill the mission’s science objectives, the OCO validation activities are focused on demonstrating that space-based retrievals of X_CO2 have random errors no larger than 0.3% (1 ppm) over a network of ground based validation sites on monthly time scales [Miller et al., 2005]. Furthermore, space-based retrievals of X_CO2 will be compared to measurements from this network of ground-based stations to detect and mitigate geographically coherent biases on regional to continental scales. We describe plans and progress to date of the OCO validation program, which consists primarily of a series of ground-based, Fourier Transform Spectrometers (FTS), that measure X_CO2 in the same spectral regions as the space-based spectrometers.

GOSAT is a satellite to measure the column densities of CO₂ and CH₄ from space globally, and it is scheduled to be launched in 2008. It has a short wavelength infrared (SWIR) Fourier transform spectrometer (FTS) which measures both the ground surface scattered solar light over land and the right reflected light (sun-glint) over ocean. Column densities of CO₂ and CH₄ will be retrieved from the SWIR (i.e. 1.6 µm and 2.0 µm bands) data and the optical path length from oxygen A-band (0.76 µm). A cloud and aerosol sensor composed of three spectral image sensors (0.380, 0.678 and 1.62 µm) is equipped, viewing the wider area than FTS. This is a joint project among Ministry of Environment of Japan (MOE), National Insitutite for Environmental Studies (NIES) and Japan Aerospace Exploration Agency (JAXA).

Exchange rates within the Global Carbon Cycle, between oceans, atmosphere and terrestrial biosphere – including the anthropogenic CO₂ production – are being traced by concentration and isotope ratio measurements of atmospheric CO₂. The background value of the stable isotope ratio of oxygen in atmospheric CO₂ is determined by oxygen exchange with the ocean surface waters. During contact with leaf water, the signature of this then evaporation-enriched groundwater (the extent still being dependent on plant physiological and environmental parameters), will be imprinted on CO₂ diffusing back out of the leaf stomata. From water cycle studies the continental effect (Rayleigh-distillation) is known, leading to precipitation strongly depleted in d¹⁸O over e.g. Siberia. This signal is also transferred into plant material. These main mechanisms within the ¹⁸O-cycle are known or under investigation. The d¹⁸O source term for atmospheric CO₂ derived from biomass burning and anthropogenic fossil fuel combustion, however, is less well-known.

We have constructed an estimate of annual-mean surface fluxes of carbon dioxide for the period 1992-6 using observational constraints from the atmosphere and from the ocean interior. The method interprets in situ observations of carbon dioxide concentration in the ocean and atmosphere using transport estimates from global circulation models.

The Atlantic's central role in the global thermohaline circulation suggests that this basin should be an important laboratory for understanding the ocean carbon cycle and possible temporal variations in that cycle. Here we present the set up and results from an oceanic box model inversion which focuses on the transport and divergence of total inorganic carbon (TIC) and anthropogenic carbon within the Atlantic.

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. 

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.  

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.