The spatial and temporal variability of aerosol optical depths in the Mojave Desert of southern California

The Mojave Desert of southern California is under constant pressure from anthropogenic influences on atmospheric pollutants and land management. Previously, the spatial, temporal, and source characteristics of aerosols over the Mojave Desert have been examined using in situ observations; however, in situ observations lack spatial coverage, and the only long-term measurements of aerosol optical depth (AOD) needed for aerosol impact studies on the local climate and biota is the AERONET site at Rogers Dry Lake. In this study, we provide the first moderately high spatial resolution (17.6 × 17.6 km2) study of AOD over the Mojave Desert of southern California using satellite data from the Multi-angle Imaging SpectroRadiometer (MISR) for the period of March 2000 to October 2005. We have demonstrated the seasonality of AOD over the entire Mojave Desert, and the spatial and temporal variability of AOD from the average AOD at national parks, military installations, and dry lakes and playas. Statistically significant differences from the Mojave Desert mean AOD can be attributed to proximity to urban sources (e.g., Rogers Dry Lake is near the Los Angeles metropolitan area) and local sources (e.g., mineral extraction at Bristol Dry Lake). The western Mojave, generally around Rogers Dry Lake and Harper Dry Lake exhibited the most sustained pattern of seasonally high aerosol optical depths throughout the year. As a result, the AERONET site at Rogers Dry Lake should not be used as a site representative of the aerosol conditions over the entire Mojave Desert of southern California.