Vertical and Long-Range Transport of Trace Gases and Aerosols
|Convener: Mark G. Lawrence | Co-Convener: Andreas Stohl|
Vertical and long-range transport of trace gases and aerosols are key factors controlling their concentrations and variability. Surface emissions have a strong direct influence on the upper troposphere via several vertical transport processes, especially cumulus convection and lifting associated with frontal systems (warm and cold conveyor belts). Downward transport occurs via accompanying subsidence, while precipitation scavenging is one of the key sinks for many gases and aerosols. Long-range and intercontinental transport result in measurable enhancements of gas and aerosol concentrations in populated and agricultural regions due to industrial and biomass burning emissions thousands of kilometers upstream. Even many "remote" marine regions are far from being free from the direct influence of relatively short-lived anthropogenically produced gases and aerosols produced over far away continents. Natural processes such as stratosphere-troposphere exchange and lightning can also influence the chemical composition of downwind locations. Numerous tools have been applied to studying transport-related issues, including observations (long-term, campaign, and satellite) and models (cloud-scale to global). We invite talks covering all aspects of this topic, and especially encourage those which synergistically combine various types of models and observations. Examples of recent field campaigns with high relevance to this session are TC4, the various POLARCAT missions, or START-08. Furthermore, extensive modelling activities focused on long-range pollutant transport are being conducted within the TF-HTAP (Task Force on Hemispheric Transport of Air Pollutants) project, from which we also welcome contributions.