Association of modeled PM2.5 with aerosol optical depth: model versus satellite

Particulate matters < 2.5 mu m (i.e., PM2.5) are very important for health as well as radiative forcing studies. But over Indian continent, there is scarcity of the observation for PM2.5 concentration which gets measured over only few locations with very coarse resolution. Limitations on resolution in space and time posed by the real-time measurements caused requirement of other measurements with high resolution in space and time. In this regard, satellite observations and model came up as good alternative as they can produce information with high resolution. Satellites and chemical transport models play a significant role and give wider option to study spatial and temporal patterns of particulate matter, especially for finer mode. In the present work, we have simulated the particulate matters (PM2.5) over the Indian continent from 4-29.5 degrees N and 67-88.5 degrees E with the help of a chemical transport model 'CHIMERE.' We found its connection with satellite estimate aerosol optical depth (AOD) from MODIS and MISR sensors. Modeled results can be set for higher resolution than satellite data, so in the absence of satellite data, these relations can be useful. Particulate matters with aerodynamic radius < 2.5 are a contributor to total aerosol load which causes columnar aerosol optical depth. In this work, we took PM2.5 concentration as an indicator of aerosol loading and thus compared it with columnar aerosol optical depth. Both approaches are coherent for various seasons on the year except monsoon as in the monsoon season availability of data from satellite was not consistent.