Consistency of dimensional distributions and refractive indices of desert dust measured over Lampedusa with IASI radiances
Other literature type
(issn: 1867-8548, eissn: 1867-8548)
In the context of the ChArMEx campaign, we present here some results
concerning the quantitative comparison between simulated and observed
radiances in the presence of atmospheric desert dust, between June and July 2013
in the southern Mediterranean Basin, in the air mass above the island of Lampedusa.
In particular, comparisons have been performed between radiances as observed
by the Infrared Atmospheric Sounder Interferometer (IASI) and those simulated
using the <i>σ</i>-IASI-as radiative transfer model, which takes into account
aerosol extinction effect through a set of fast parameterizations.
Simulations have been carried out using different sets of input complex
refractive indices, which take into account the parent soils of the aerosols.
Their accuracy also relies on the quality of the characterization of desert
dust microphysical properties, achieved through direct measurements in the
ChArMEx experiment. On the one hand, the fact that the model can ingest such
a variable input proves its feasibility. On the other hand, this work goes
through a direct validation of different refractive index sets for desert
dust in the thermal infrared, and pursues an assessment of the sensitivity of
IASI data with respect to the dimensional distribution of desert dust
particles. Results show a good consistency between calculations and
observations, especially in the spectral interval 800–1000 cm<sup>−1</sup>;
further, the comparison between calculations and observations suggests that
further efforts are needed to better characterize desert dust optical
properties in the shortwave (above 2000 cm<sup>−1</sup>). Whatever the case, we show
that it is necessary to properly tune the refractive indices according to the
geographical origin of the observed aerosol.