Hydrogen, Methane and Nitrous oxide:
Trend variability, budgets and interactions with the biosphere

OBJECTIVES

The overall project-objectives of HYMN are:

1. To improve the process modelling of the land-biosphere-atmosphere exchange of the HYMN gases and to provide global and regional estimates of their natural sources and sinks.
2. To contribute to global monitoring by provision of multi-year global satellite data sets of the CH4 and CO distribution and long-term time series for CH4 and N2O at a range of observing stations.
3. To provide advice on the further optimisation of monitoring networks for the HYMN gases.
4. To quantify atmospheric loss of CH4 and H2 and the impact of changing anthropogenic and natural (climate-induced) emissions on regional OH trends and on current and future global CH4 and H2 levels.
5. To quantify how the possible future change to a hydrogen economy will affect the H2 distribution and the distribution of CH4 and O3 through changes in emissions of H2 and pollutants (NOx, CO, VOCs).
6. To evaluate the simulations with a novel coupled atmospheric chemistry-biosphere model for CH4, N2O and H2 by comparison with ground based and satellite observations on a global and regional scale.
7. To make new estimates of the sources and sinks of CH4 and H2 including their temporal and spatial variability.