Regional-Scale Modeling of Air Pollutants in South Asia
Speaker: Rajesh Kumar, NCAR
When: Wednesday, January 15, 2014, 3:30 p.m. Mountain Time
Location: Room 2A305, DSRC (NOAA Building), 325 Broadway, Boulder
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The rapid increase in anthropogenic emissions of key trace gases and aerosols in South Asia has led to such poor air quality that South Asia is identified as one of the regions with highest premature mortality rates. The air quality problem is further amplified by occasional outbreaks of dust from the Great Indian Thar Desert. In addition to public health, the pollutants emitted in South Asia also have a wide range of potential consequences for agriculture, freshwater resources and climate. Therefore, it is very important to understand the processes controlling the distribution and variability of pollutants in South Asia. The available in situ observations of trace gases and aerosols lack sufficient space-time coverage for conducting such an analysis and thus use of chemical transport model results and satellite observations becomes essential to advance our understanding of pollution in this region. In the first part of my presentation, I will focus on a natural component of air pollution, i.e. dust aerosols and will describe the effects of a typical pre-monsoon season (MAM) dust storm on regional-scale aerosol optical properties, radiation budget and tropospheric chemistry in northern India. In the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), a photolysis scheme is updated and a new module for heterogeneous loss of trace gases on dust surface is added to extend the model's ability to simulate tropospheric chemistry in the presence of dust aerosols. The updates are found to improve the agreement between the model and observations during the dust storm. In the second part, I will focus on the anthropogenic component of air pollution, particularly on carbon monoxide (CO) and black carbon (BC). A number of tracers are included in the model to keep track of CO and BC coming from different source types and regions. The model simulated CO and BC are compared against observations from a ship cruise and used to examine various features deduced from ship-borne observations of CO and BC. An outlook towards future research in this region will be presented at the end.