Trace gas/aerosol boundary concentrations and their impacts on continental-scale AQMEII modeling domains

Copyright 2011 Elsevier B.V., All rights reserved.Over twenty modeling groups are participating in the Air Quality Model Evaluation International Initiative (AQMEII) in which a variety of mesoscale photochemical and aerosol air quality modeling systems are being applied to continental-scale domains in North America and Europe for 2006 full-year simulations for model inter-comparisons and evaluations. To better understand the reasons for differences in model results among these participating groups, each group was asked to use the same source of emissions and boundary concentration data for their simulations. This paper describes the development and application of the boundary concentration data for this AQMEII modeling exercise. The European project known as GEMS (Global and regional Earth-system Monitoring using Satellite and in-situ data) has produced global-scale re-analyses of air quality for several years, including 2006 (http://gems.ecmwf.int). The GEMS trace gas and aerosol data were made available at 3-hourly intervals on a regular latitude/longitude grid of approximately 1.9° resolution within 2 "cut-outs" from the global model domain. One cut-out was centered over North America and the other over Europe, covering sufficient spatial domain for each modeling group to extract the necessary time- and space-varying (horizontal and vertical) concentrations for their mesoscale model boundaries. Examples of the impact of these boundary concentrations on the AQMEII continental simulations are presented to quantify the sensitivity of the simulations to boundary concentrations. In addition, some participating groups were not able to use the GEMS data and instead relied upon other sources for their boundary concentration specifications. These are noted, and the contrasting impacts of other data sources for boundary data are presented. How one specifies four-dimensional boundary concentrations for mesoscale air quality simulations can have a profound impact on the model results, and hence, this aspect of data preparation must be performed with considerable care.Peer reviewedFinal Accepted Versio

Theoretical and synoptic study of western disturbance

The theoretical part of the papel deals with the stability characteristics of the observed mean zonal current over lndia and neighbourhood in winter. The analysis shows that the mean zonal current is unstable with respect to a small perturbation superimposed on it. The synoptic part deals with a case study of a westem disturbance which developed into a depression. The developrnent of the westem disturbance is similar to the development of a baro- clinically unstable disturbance. Power spectral analysis of the meridional component of wind shows a periodicity of 8-10 days for westem disturbances. The estimated wavelength of the westem disturbance is in good agreement with the theoretically determined most unstable wavelength.Pages: 193-20

The AQMEII Two-continent Regional Air Quality Model Evaluation Study - Fueling Ideas with Unprecedented Data

Although strong collaborations in the air pollution field have existed among the North American (NA) and European (EU) countries over the past five decades, regional-scale air quality model developments and model performance evaluations have been carried out independently unlike in the climate or global air quality modeling community. Recognizing the need to build international cooperation for rapidly advancing the science in regional-scale photochemical air quality modeling systems, a team of scientists embarked on a project known as Air Quality Model Evaluation International Initiative (AQMEII) in 2009 (Galmarini et al., 2010; Rao et al., 2010). The aim of AQMEII is to provide a permanent forum for constantly monitoring the state of advancement of regional-scale air quality models and model evaluation methodologies, identifying knowledge gaps in air quality science and developing methodologies to evaluate uncertainty in model results, (http://aqmeii.jrc.ec.europa.eu/).JRC.DDG.F.9-Sustainable Transport (Ispra

Air Quality Model Evaluation International Initiative (AQMEII) - Advancing State-of-Science in Air Pollution Modeling and its Applications

In early 1980's, American Meteorological Society (AMS) and U.S. Environmental Protection Agency (EPA) held two workshops to discuss and recommend methods for evaluating plume dispersion models (Fox, 1981 and 1984). AMS and EPA also held another workshop in 1984 to discuss evaluation issues relating to regional-scale air quality models, but the workshop participants did not recommend any specific methods for the model performance evaluation (Demerjian, 1985). Hence, the statistical metrics identified by the first AMS and EPA workshop continue to be used for evaluating Gaussian dispersion models as well as numerical regional-scale air quality models, not only in the United States but also in other countries. Although the focus in 1970¿s and 1980¿s was primarily on urban air pollution models, it is well-known that pollution problems such as acid rain, ozone, and fine particulate matter are regional in scope, requiring regional-scale multi-pollutant models.JRC.DDG.F.9-Sustainable Transport (Ispra