###PM10,PM2.5 observation assimilation for WRF CHEM based on GSI###

based on this paper Implementation of aerosol assimilation in Gridpoint Statistical Interpolation (v. 3.2) and WRF-Chem (v. 3.4.1)

http://www.geosci-model-dev.net/7/1621/2014/gmd-7-1621-2014.pdf