Introduction
The terrestrial biosphere and the oceans are known to emit large quantities of reactive VOCs and trace gases that help to drive oxidant chemistry in the troposphere, and can feedback on changes in climate. The magnitude and spatial and temporal variability of these fluxes, and how they respond to changes in climate, is not well understood.
We approach this subject in several ways: using satellite data, aircraft and ground-based data, and by performing plant experiments in controlled greenhouse environments. Together, these approaches help better understand the factors that determine the variability in reactive trace gas fluxes from the biosphere. Our work with CO₂ and other longer-lived biospheric gases is described in other sections.

Areas of Active Research

• Space-based Constraints on Biogenic Emission Estimates
  We are interested in biogenic fluxes from the terrestrial and marine biospheres. Regarding the terrestrial biosphere, we have developed a methodology to estimate terrestrial biogenic emissions using observations of formaldehyde (HCHO), a high yield product from the oxidations of VOCs. We have demonstrated and evaluated this methodology using satellite observations of column formaldehyde from the Global Ozone Monitoring Experiment (GOME) over North America [1,2,3,4,5]. We are currently extending this analysis to tropical ecosystems which account for more than 75% of global biogenic VOCs.
• OP3
  Dr Palmer is a Co-I on this NERC-funded consortium project ("Oxidant and particle photochemical processes above a Southeast Asian tropical rainforest"). The main aims of this project are 1) to understand how emissions of reactive biogenic VOCs from a Southeast Asian tropical rainforest affect regional-scale production and processing of oxidants and particles in the troposphere, and 2) to better understand the impact of these processes on local, regional and global scale composition, chemistry and climate. This will be achieved by integrating ground-based, aircraft and satellite observations. This project runs between 2007-2010, with measurement campaigns during the Spring and Autumn of 2008.
• AMMA
  This is a NERC-funded consortium project ("African Monsoon Multidisciplinary Analyses"). It is multi-platform mission that will be conducted over tropical West Africa during summer 2006. In collaboration with Dr Ally Lewis (University of York) we will help analyze the factors that control biogenic fluxes over this region, and put them into a regional context using the aircraft and satellite data (see above and [7]).
• Laboratory Plant Experiments and Surface Flux Parameterization
  In collaboration with Dr Alex Guenther (National Center for Atmospheric Research) we will be conducting laboratory plant experiments that will subsequently be parameterized and used for global chemistry-modelling studies [8]. In particular, we will be assessing the factors that regulate plant fluxes of isoprene.