Improved characterisation of aerosol coarse mode properties using measurements of spectral optical depth and aureole measurements using GRASP code.
Abstract
Previous efforts described GRASP-AOD application, where GRASP code was adapted to obtain aerosol optical size information from the measurements of the direct Sun beam only. Those studies have pointed out the low sensitivity to coarse mode properties of Aerosol Optical Depth (AOD) measurements in the spectral range between 340-1640 nm. An optimal selection of the initial guess was revealed as an important factor for improving the characterization of coarse mode. This information could be adapted from climatological values or other sources. Another idea to improve the characterization of the coarse mode is to complement the AOD measurements with aureole measurements. In fact, the angular distribution of scattered light is known to be strongly dependent on coarse mode particle size, specially at the aureole region (Θ = 3-10°). The main interest of this approach would be to obtain better aerosol information in those situations where there are AOD measurements and aureole measurements while the sky/radiances in complete scattering angle range are not available from the standard radiance measurement routines due to a partial cloudiness. It should be noted that aureole measurements do not provide the necessary information to retrieve such aerosol properties as complex refractive index and fraction of spherical particles. Therefore, the refractive index values, which were necessary to run GRASP-AOD, are still taken from climatologies for inverting AOD together with aureole sky-radiances measurements. The present work shows the retrieval improvements provided by this new approach. These combined retrievals using aureole and AOD measurements from several AERONET sites are compared to GRASP-AOD only retrievals.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA211.0010T
- Keywords:
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- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES;
- 3359 Radiative processes;
- ATMOSPHERIC PROCESSES;
- 3360 Remote sensing;
- ATMOSPHERIC PROCESSES