Satellite derived aerosol optical depth products in support of UAE2

The United Arab Emirates Unified Aerosol Experiment (UAE²), a field campaign conducted in August – September 2004, provided a unique opportunity to study detailed aerosol characteristics over the complex Middle East desert environment and validate aerosol algorithms and models. In support of UAE² flight operations and post-mission science, the Naval Research Laboratory (NRL) provided near real-time satellite-derived aerosol optical depth (AOD) imagery products over the open water regions within the Arabian Gulf. The retrievals (NRL-AOD) are based on linearized single-scatter theory with an aerosol size distribution model obtained from visible sensors on board the NOAA-AVHRR and NASA-MODIS sensors. While more applicable to pristine maritime aerosol environments, the AOD retrievals were found to perform surprisingly well under the complex and optically thick Arabian dust conditions. The wealth of data obtained from airborne and ground-based instruments within UAE² provided the opportunities to validate the NRL-AOD algorithm and examine other applications geared toward operational interests.

Leveraging UAE² datasets, this paper presents improvements to the NRL-AOD algorithm, particularly within desert dust conditions. Of particular focus are the phase function and aerosol absorption parameters, which are typically unavailable and very difficult to parameterize. AOD output will be compared to a variety of ground and airborne instruments, including AERONET stations along the coastal and island stations along the Arabian Gulf. Another aspect of this paper includes the conversion of the AOD product to horizontal and slant range visibility measurements, as supported from ground-based observations as well as extinction measurements from aircraft data.