Measuring volcanic ash and windblown sand with IASI
Résumé
Satellite sounders are ideal for measuring the highly variable global atmospheric aerosol
distributions. IASI is slowly putting infrared aerosol sounding on the map and proving to be a
valuable complement to the more traditional SWIR/UV/VIS aerosol measurements. Here we present
our recent progress in the sounding of volcanic ash and windblown sand aerosols from this
instrument. Aerosol detection and retrieval techniques are reviewed, leading up to the presentation of
a new dust retrieval algorithm. The retrieval combines a well-tuned detection algorithm with a
feedforward neural network, rigorously accounting for surface effects (emissivity, temperature) as
well as the state of the atmosphere. By explaining the underlying principles we demonstrate the
inherent advantages of the approach, but also highlight some of its disadvantages such as its
dependence on accurate ancillary data. The resulting 8-year dataset of dust optical depth from IASI is
presented. We derive global distributions, a monthly climatology and timeseries over selected
regions. We end this talk with example validation efforts using both aircraft and ground-based data