The influence of air-sea fluxes on atmospheric oxygen can be separated from terrestrial influences using the tracer Atmospheric Potential Oxygen (APO).  Data collected by the Scripps atmospheric oxygen flask sampling network exhibits interannual variability in APO coherent over the northern hemisphere.  The timing of these changes correlates with climatic changes in the North Pacific.

The results of an optimisation of inter-annual methane sources and sinks calculated by inversion of atmospheric observations are presented and analysed for the 1984-2003 period. We focus our presentation on sources trend and inter-annual variability. Comparisons with bottom-up estimates are presented for biomass burning and wetlands emissions (only in the poster).

A combined study of micrometeorological flux measurement of carbon dioxide (CO₂) and methane (CH₄) and measurement of their stable carbon isotopes at a paddy field indicated that CH₄ production can affect not only greenhouse gas budget of wetland ecosystem but also isotopic signature of respired CO₂.

Based on simulations with high-resolution transport models we investigate the detectability of surface flux signals in the atmospheric CO₂ concentration and infer some general guidelines for the sampling of the continental troposphere for the purpose of constraining mid-latitude land carbon sinks.

The Total Carbon Column Observing Network is a new network of ground-based solar observatories, dedicated to column measurements of greenhouse gases.  We present CO₂ column abundances observed in Park Falls, Wisconsin and Lauder, New Zealand during May 2004 – June 2005.  In Park Falls, Wisconsin, the peak-to-peak variation of column-average CO₂ is approximately 13 ppmv.  In Lauder, New Zealand, the peak-to-peak variation of column-average CO₂ is approximately 4 ppmv.  Assuming a secular trend of 2 ppmv yr^-1, we infer a peak-to-peak seasonal amplitude of 11 ppmv and 2 ppmv for Park Falls and Lauder respectively.  These values are higher than model predictions by Olsen and Randerson [2003].

Measurements of CO₂ concentration are carried out on a weekly basis since 1992 on the island of Lampedusa (35.5°N, 12.6°E), in the Mediterranean. Measurements are based at the Station for Climate Observations, which rests on a rocky plateau (45 m asl) on the North-Eastern coast of the island, and are made with a NDIR analyzer. World Meteorological Organization (WMO) reference standards are used for calibrations.  Continuous measurements were started in 1998; they were interrupted in early 2003, and activated again in 2005. The continuous observations show evidence of a small daily cycle (amplitude < ±1 ppm) only during the months of June, July, and August. Mean annual cycles derived from weekly flask measurements show a dependency on the wind origin: the annual cycle and the annual CO₂ mean are smaller for winds originating from the Southern sectors, than for winds from Northern sectors. The continuous measurements were combined with daily backward airmass trajectories to identify the dependency of the CO₂ amount on the airmass origin. Trajectories provided by National Oceanic and Atmospheric Administration / Air Resources Laboratory (Hysplit) are used. During winter, low CO₂ is generally connected to Southern/South-Eastern airmasses. In summer airmasses from North often display lower CO₂ content, due to the influence of the European sink.

Numerical models of the carbon cycle are becoming increasingly sophisticated. One result of this is that these models now require fossil-fuel carbon-dioxide emissions data with sub-annual (e.g., seasonal) time resolution. They also require finer spatial resolution than national averages (i.e., than one point per nation). Finer spatial resolution is especially needed for countries as large in area as the United States of America (U.S.A.). Here we present a summary of monthly data for the entire nation, and annual data for each state in the U.S.A.

This paper presents estimates of the ¹³C Suess effect and anthropogenic carbon concentration increase in the Nordic Seas since 1981.

In recent years our knowledge of gas exchange across the air-sea interface at the process level has improved as a consequence of new instrumentation and novel use of injected and natural tracers.  However, there remains significant uncertainty in the extrapolation of these results to larger scales, especially for studies focusing on global-scale processes such as the earth's carbon cycle.

The oxygen isotopic composition of atmospheric CO₂ can help constrain local- to global-scale biophysical processes and partition measured net ecosystem CO₂ fluxes into gross fluxes. Although current models still lack key features controlling gross ecosystem CO¹⁸O fluxes, considerable improvements have been achieved in the last four years. In this study we examine the influence on atmospheric CO¹⁸O of 1) a delayed seasonal cycle in soil water isotopes (relative to rain water) and 2) a new one-way flux model of night-time leaf respiration [Cernusak et al., 2004]. The latter covaries with enhanced night-time stomatal conductance, for which evidence arose recently [e.g. Snyder et al., 2003].