Biomass burning is an important source of atmospheric CO₂, aerosols and chemically important gases. It is as important to global chemistry as industrial activities in the developed world [Crutzen and Andreae, 1990]. Biomass burning is a key component of the global carbon budget, currently releasing 2.6 GtC from fires in the tropical and subtropical ecosystems (van der Werf et al. [2003], to be compared to the 5.6 GtC released from fossil fuels) to the atmosphere each year, most of it being emitted in the form of carbon dioxide, although there is important spread amongst various estimates. Biomass burning contributes up to 40% of gross atmospheric CO₂ (IPCC, 2001), 38% of tropospheric O₃, and 10 % of CH₄.

Existing instruments for measuring atmospheric profiles of carbon dioxide can be very sensitive, but are all large and bulky and must be flown using aircraft or large, research gondolas.  This work reports on the development of a stand-alone, lightweight CO₂ sensor for use on balloon sondes.  This device will have sub part-per-million (ppm) sensitivity and weigh less than 1 kg.

Measurements of atmospheric O₂/N₂ ratio and CO₂ concentration are presented over the period 1989 to present from the Scripps Institution of Oceanography global flask sampling network. The data are used to make estimates of land and ocean sinks over various time scales. The oceanic and land biotic sinks are estimated to be 1.9±0.6 (ocean) and 1.2±0.8 Pg C/yr (land) over the period Jan. 1990-Jan. 2000 and 2.2±0.5 (ocean) and 0.5±0.7 Pg C/yr (land) over the period Jan. 1993-Jan. 2003. These estimates make allowance for oceanic O₂ and N₂ outgassing based on observed changes in ocean heat content and estimates of the relative outgassing per unit warming. The recent ocean sink is consistent, to within the uncertainties, with estimates of the accumulation of anthropogenic CO₂ in the ocean since 1800, assuming the oceanic sink varied over time as predicted by a box-diffusion model. The possibility that the ocean sink is being reduced slightly by climate feedbacks, as predicted by some models, is not ruled out, however.

An inverse modeling system has been developed based on the Bayesian principle for estimating the carbon fluxes of the 48 regions globally and 28 regions over North America in monthly steps for 2003 using CO₂ concentration measurements at 95 atmospheric baseline stations and with regularization using remote sensing-based surface flux field. Preliminary inversion results of global carbon flux and a carbon flux field over North America have been obtained.

Stable isotope measurements of atmospheric carbon dioxide from the CSIRO global flask sampling program with improved traceability to the international primary reference material VPDB (Vienna Pee Dee Belemnite), and with improved uncertainty estimates, are presented. The measurements have been used with an improved time dependent inversion model to reassess terrestrial and oceanic contributions to the interannual variability in atmospheric CO₂.

A new research project has started in 2003 to develop Continuous CO₂ Measurement Equipment (CME) and Automatic Air Sampling Equipment (ASE) for commercial airlines. CMEs are planning to be installed on five aircrafts and fly to South East Asia, East Asia, Europe, North America, Pacific and Australia. Routine air sampling by ASE will be done twice a month between Japan and Australia. After issuing the certification, first observation flight by Boeing 747-400 will be conducted in October, 2005. Preliminary observation by small research aircraft indicates that CME produces reasonable results.

CHIOTTO – Continuous HIgh-precisiOn Tall Tower Observations of greenhouse gases – is a European Union-funded project which has as objective to build an infrastructure for the continuous monitoring of greenhouse gas concentrations across Europe above the surface layer using tall towers (~300m height). For this purpose a new analysis system for continuous atmospheric measurements was built and tested at Max Planck Institute for Biogeochemistry, Jena, Germany and was recently installed at a 300 m tower close to Bialystok, Poland (Lat 53°14'N, Long 23°01'E, Alt 180m), as part of the “CHIOTTO” tall tower network. Since July 2005 this system is measuring quasi-continuously the atmospheric concentration of CO₂, CH₄, CO, N₂O, SF₆ and the O₂/N₂ ratio as well as meteorological parameters (atmospheric pressure, temperature, humidity; wind speed and direction) from 5 heights on the tower ranging from 5 to 300 m. The measurement devices are: an Oxzilla O₂ fuel cell analyzer, a LiCor 7000 NDIR CO₂ analyzer, an Agilent gas chromatograph (GC) with flame ionization detector (FID) and electronic capture detector (ECD) for CH₄, CO, N₂O, SF₆. The challenge was to build a reliable automatic system which can run continuously with very little maintenance and to fulfill at the same time the high precision requirements for all the measured species prescribed by the CHIOTTO project goals. The high temporal resolution achieved will capture short term events and diurnal variability. In addition, the system is planned to run for at least several years in order to observe long-term trends as well. We describe the technical setup of the measurement system, the region of influence of the station and present the first months of data if available: correlations between species, observed short term variability patterns and their relation to meteorology and air parcel paths.

We report on the set-up of and first experiences with a medium-precision CO₂ concentration monitoring network in Europe, linked to existing flux towers. The system is to be embedded in an integral GHG monitoring system to be developed for the Netherlands and into the CABOEUROPE effort to quantify the European carbon balance. The proof of concept has not been fully satisfactory as yet, but work continues.

The Dole-Morita effect (DME) describes the d¹⁸O enrichment of atmospheric O₂ with respect to ocean water [Dole 1935, Morita 1935]. The magnitude of the DME (23.8 ± 0.1‰ at present, Horibe et al. [1973]) varies over geologic time scales, and might have changed as a result of human activity. Such variations are preserved in the air enclosed in polar firn and ice. Here, we explore the potential effects of human activity on the DME. We estimate that global changes in the land biosphere may have led to a decrease in the DME in the order of 0.07‰ over the last 150 years. We then predict profiles of d¹⁸O-O₂ in firn air resulting from a range of atmospheric scenarios using a model [Severinghaus and Battle, submitted] and compare the simulated profiles to measurements of air samples extracted from polar firn.