Aerosol optical depth images derived from MODIS sensor near Hawaii: volcano plumes, Asian plumes, and clear sky

摘要

The University of Hawaii routinely collects direct broadcast MODIS images over Hawaii. Using this data set we process real time satellite images of aerosol optical depths around Hawaii using our custom algorithm. MODIS channels 1 and 2 (~ 645 and ~ 858 nm) are used to derive aerosol optical depth spatial and temporal properties. The use of MODIS channels 1 and 2 provides images with 250 m resolution resulting in improved cloud detection. Due to this improvement, background aerosol optical depths values remain low even in regions of many small clouds. Although cloud rejection is not expected to be perfect, using 250 m resolution data provides a significant improvement over 1 km resolution data. In order to correct for surface reflection, meso-scale wind fields from the Regional Spectral Model (from the National Center for Environmental Prediction) and synoptic scale winds (from National Center for Environmental Prediction) are interpolated to the satellite pixel size. The use of meso-scale wind fields is required for the complex wind fields in and around the Hawaiian Islands. Here we will discuss the aerosols encountered in Hawaii, and provide examples of interesting aerosol optical depth images around Hawaii.