Local- to global scale canopy interactions relevant to the exchange of reactive compounds and aerosols
1 Department of Environmental Sciences, Wageningen University and Research Centre
O 6.4 in SVAT-Modeling and scale interactions
08.10.2009, 11:15-11:40, Kutschenhaus
Atmosphere-biosphere exchange of reactive nitrogen (Nr) and reactive carbon (Cr) plays a key role in the Earth system through the regulation of atmospheric- and biogeo-chemistry. It is also relevant to climate through its role in the regulation of the oxidizing capacity, production of Secondary Organic Aerosols (SOA) and affecting ecosystem functioning through nutrient and ozone (O3) deposition. The global biosphere emits about 1.3 PgC yr-1 of reactive carbon in the form of Volatile Organic Compounds (VOCs), exceeding anthropogenic emissions by a factor of 10. Soils are a large source of nitric oxide (NO), a Nr compound which controls the NOx (NO+NO2, nitrogen dioxide) budget in remote and rural areas while emissions from fossil fuel combustion dominate the NOx budget in industrialized areas.
One of the uncertainties in the global biogenic emission inventories is the role of the canopy interactions between emissions, dry deposition, turbulence and chemistry. These interactions result for example in an about 50% decrease in the biogenic source of NOx as simulated explicitly with an implementation of a multi-layer canopy exchange model in a chemistry-climate model. This model is now also applied to study the role of canopy interactions for VOC and SOA exchange through consistent simulation of in-canopy Nr and Cr sources and sinks at the site- (using a single column version of the chemistry-climate model) and global scale. I will discuss the ongoing research on local- to global scale chemical canopy interactions by showing the results of detailed evaluation of the multi-layer model for a number of sites and global scale implications. In addition, I will address the main uncertainties in these simulations of canopy interactions with a particular focus on the role nocturnal and daytime turbulent mixing conditions and leaf- to canopy scale interactions between emissions and dry deposition.
Full presentation file: fp_O_6.4 (24.11.2009 17:11)