Detecting Mineral Dust Aerosols: Aerosol Retrieval Continuity in Transition from MODIS to VIIRS

Abstract

Mineral dust is one of the biggest contributors to atmospheric optical thickness (AOT), and it is also one of the biggest sources of uncertainty in Earth’s climate system due to a lack of reliable observations on the global scale. Mineral dust in the atmosphere also impacts terrestrial and oceanic ecosystems and human health. In order to understand its impact on human health, it is important to properly establish the levels of dust that the population is being exposed to. This can be done by monitoring stations, but it does not give accurate spatially distributed pollutant information for the locations that are far from the monitoring sites. Satellite-based measurements provide a useful tool for detecting mineral dust events, as well as monitoring their spatial and temporal evolution and the resulting impact on air quality, especially for areas where there are no surface measurements (such as over the ocean). The Moderate Resolution Imaging Spectroradiometer (MODIS) on board the NASA Terra and Aqua satellites has provided retrievals of atmospheric AOT and related parameters since 2000. Due to the aging of the MODIS sensor, the transition of AOT retrievals from MODIS to VIIRS (Visible Infrared Imaging Radiometer Suite) is inevitable for long term data analyses. VIIRS is one of the key instruments onboard the Suomi National Polar-Orbiting Partnership (Suomi NPP) spacecraft launched in late 2011, and also on the NOAA-20 spacecraft launched in late 2017. The Deep Blue AOT retrieval algorithm developed by Hsu et. al (1) for MODIS data has recently been adapted for VIIRS, and the first global long-term retrievals from SNPP VIIRS have been created. This poster will present SNPP VIIRS Deep Blue AOT and Aqua MODIS (Collection 6) Deep Blue AOT results during mineral dust events that occurred in 2015, and show preliminary results of comparisons against surface-based AERONET AOT retrievals. The Deep Blue AOTs from MODIS and VIIRS will be investigated to determine whether biases exist during the dust events.

(1) C. Hsu et al: “Enhanced Deep Blue aerosol retrieval algorithm: The second generation”. Journal of Geophysical Research: Atmospheres, Vol. 118, 9296–9315, 2013.