East Asia is the second-largest mineral dust source in the world, after the Sahara. When dispersed in the atmosphere, mineral dust can alter the Earth’s radiation budget by changing the atmosphere’s absorption and scattering properties. Therefore, the mineralogical composition of dust is key to understanding the impact of mineral dust on the atmosphere. This paper presents new information on mineralogical dust during East Asian dust events that were obtained from laboratory dust measurements combined with satellite remote sensing dust detections from the Infrared Atmospheric Sounding Interferometer (IASI). However, the mineral dust in this region is lifted above the continent in the lower troposphere, posing constraints due to the large variability in the Land Surface Emissivity (LSE). First, a new methodology was developed to correct the LSE from a mean monthly emissivity dataset. The results show an adjustment in the IASI spectra by acquiring aerosol information. Then, the experimental extinction coefficients of pure minerals were linearly combined to reproduce a Gobi dust spectrum, which allowed for the determination of the mineralogical mass weights. In addition, from the IASI radiances, a spectral dust optical thickness was calculated, displaying features identical to the optical thickness of the Gobi dust measured in the laboratory. The linear combination of pure minerals spectra was also applied to the IASI optical thickness, providing mineralogical mass weights. Finally, the method was applied after LSE optimization, and mineralogical evolution maps were obtained for two dust events in two different seasons and years, May 2017 and March 2021. The mean dust weights originating from the Gobi Desert, Taklamakan Desert, and Horqin Sandy Land are close to the mass weights in the literature. In addition, the spatial variability was linked to possible dust sources, and it was examined with a backward trajectory model. Moreover, a comparison between two IASI instruments on METOP-A and -B proved the method’s applicability to different METOP platforms. Due to all of the above, the applied method is a powerful tool for exploiting dust mineralogy and dust sources using both laboratory optical properties and IASI detections.
<p>Mineral dust is the most abundant natural dust in the atmosphere. It has direct and indirect effects on the radiative budget altering climate and air quality. These effects are directly dependent of the mineralogical composition and microphysical properties of the transported dust in the atmosphere.</p><p>High spectral resolution Infrared remote sensing technology has shown the ability to characterize different atmospheric components from local to global scale. In particular, the atmospheric aerosols are quantified using hyperspectral infrared spectrometers and processing algorithms since to achieve these measurements, a perfect knowledge of mineral dust optical properties is required i.e. extinction coefficient and complex refractive indices.</p><p>East Asia presents the second largest dust source in the world after Sahara. The atmospheric dust in this region has a diversity in its mineralogical composition; rich in silicates but also in carbonates that present a tracer of this region. On the other hand, the dust is uplifted in the low troposphere leaving satellite remote sensing detections with Land Surface Emissivity (LSE) constraints.</p><p>To cross these challenges, Infrared Atmosphere Sounding Interferometer (IASI) observations were used with all its advantages: continuous spectrum, day and night, ocean and land detections, high spectral resolution and low radiometric noise. A new LSE optimization method was developed to correct the IASI spectra. Then, a semi-quantitative method was applied based on laboratory measurements of suspended mineral dust coupled with optimized spectral detections, to obtain new mineralogical dust extinction weights. These weights depend on the chemical composition, the size distribution and the concentration, by this means a retrieval of the latter parameters was performed using a new radiative transfer algorithm (ARAHMIS) developed at Laboratoire d&#8217;Optique Atmosph&#233;rique (LOA).</p><p>Therefore, we present the results of dust chemical and physical parameters (mineralogy, effective radius and concentration) obtained using Infrared Atmospheric Sounding Interferometer IASI data with laboratory optical properties, during dust storm events in East Asia.</p>
<p>Large desert lands such as Sahara, Gobi or Australia present main sources of atmospheric mineral dust caused by intense dust storms. Transported dust particles undergo physical and chemical changes affecting their microphysical and optical properties. This modifies their scattering and absorption properties and alters the global atmospheric radiative budget.</p><p>Currently, remote sensing techniques represent a powerful tool for quantitative atmospheric measurements and the only means of analyzing its evolution from local to global scale. In order to improve the knowledge of atmospheric aerosol distributions, many efforts were made particularly in the development of hyperspectral infrared spectrometers and processing algorithms. However, to fully exploit these measurements, a perfect knowledge of Complex Refractive Index (CRI) is required.</p><p>In that purpose, a new methodology&#160;<sup></sup>based on laboratory measurements of mineral dust in suspension coupled with an optimal estimation method has been developed. This approach allows getting access to CRI of several desert samples with various chemical compositions.</p><p>Here, we present the first results of the physical parameters (effective radius and concentration) retrievals using Infrared Atmospheric Sounding Interferometer IASI data, during dust storm events. The latter use the CRI of different desert samples obtained in laboratory and a new radiative transfer algorithm (ARAHMIS) developed at Laboratoire d&#8217;Optique Atmosph&#233;rique LOA.</p>
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