Evaluating atmospheric aerosol removal processes through integration of global modeling and satellite data
Aerosols can influence the energy balance of the Earth-Atmosphere system with profound effect on regional climate. Emissions affect the quantity and location of aerosols, while atmospheric processes govern aerosol lifetimes and transport. Here we evaluate the ability of a global atmospheric model to represent the atmospheric processes regulating the global distribution of aerosols and magnitude of aerosol radiative forcing. We focus on anthropogenic sulfur and carbonaceous species, which comprise 50% to more than 90% of fine mode aerosols in continental outflows, but exclude plumes dominated by dust in order to focus on industrial emissions. Models are frequently evaluated by comparing model output with observations, but uncertainties in many factors at any given location may contribute to model-observation agreement or discrepancy. To understand aerosol behavior, we identify areas which on some spatial and temporal scales are subject to a limited suite of atmospheric aerosol removal processes, such as convection, scavenging, and wet or dry deposition. The Community Atmosphere Model (CAM) is used to simulate atmospheric aerosol concentrations and identify regions and times in which aerosol atmospheric burden or aerosol optical depth (AOD) is influenced primarily by one of these atmospheric processes. Appropriate regions are identified in a series of sensitivity studies. Limiting the investigation to areas with one dominant atmospheric process allows more robust comparison of model output and observations by reducing the number of factors contributing to uncertainty. For regions identified by CAM where modeled aerosol burden is most sensitive to convection and scavenging in warm and cold clouds, modeled AOD is compared with that retrieved by the Moderate Resolution Imaging Spectroradiometer (MODIS). Additionally, where aerosol burden has a seasonality dominated by a single process, comparison of the amplitude of seasonality between modeled and observed AOD is used to evaluate the modeled representation of that process.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 0345 Pollution: urban and regional (0305;
- 3311 Clouds and aerosols