Monitoring of aerosol patterns along the river valleys of Nepal using MODIS visible channels

MODIS satellite images show that the Himalayas act as a barrier for the aerosols being transported from the Indian Gangetic Plains (IGP).These accumulated aerosols in the pre-monsoon season not only affect the radiation budget but can also have a profound impact on the evolution of orographically induced clouds and the local hydrological cycle. However, the coarse spatial resolution (10km*10km to reduce signal noise ratio) of MODIS aerosol products cannot resolve the effect of local terrain in the spatial organization of the aerosol plumes, which is critical to study aerosol-cloud rainfall interactions in this region. However, high resolution images from MODIS visible channels in this region have the ability to show the organization of the aerosols along the river valleys and lower plains in the Himalayas. Here, we present a study monitoring of this aerosol pattern evolution along the river valleys by applying object oriented classification algorithms and GIS technics on the MODIS visible channels to extract the aerosols extent evolution over the pre-monsoon season (March - May) for the entire MODIS era (2000 - 2009).