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| Titel |
Analysis of the sensitivity of thermal infrared nadir satellite observations to the chemical and micro-physical properties of upper tropospheric-lower stratospheric sulphate aerosols |
| VerfasserIn |
Pasquale Sellitto, Geneviève Sèze, Bernard Legras |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250113080
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| Publikation (Nr.) |
 EGU/EGU2015-13277.pdf |
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| Zusammenfassung |
| Secondary sulphate aerosols are the predominant typology of aerosols in the upper
troposphere/lower stratosphere (UTLS), and can have an important impact on radiative
transfer and climate, cirrus formation and chemistry in the UTLS. Despite their importance,
the satellite observation at the regional scale of sulphate aerosols in the UTLS is limited. In
this work, we address the sensitivity of the thermal infrared satellite observations to
secondary sulphate aerosols in the UTLS. The absorption properties of sulphuric acid/water
droplets, for different sulphuric acid mixing ratios and temperatures, are systematically
analysed. The absorption coefficients are derived by means of a Mie code, using refractive
indexes taken from the GEISA (Gestion et Etude des Informations Spectroscopiques
Atmosphériques : Management and Study of Spectroscopic Information) spectroscopic
database and log-normal size distributions with different effective radii and number
concentrations. IASI (Infrared Atmospheric Sounding Interferometer) and SEVIRI
(Spinning Enhanced Visible and Infrared Imager) pseudo-observations are generated
using forward radiative transfer calculations performed with the 4A (Automatized
Atmospheric Absorption Atlas) radiative transfer model, to estimate the impact of the
absorption of idealized aerosol layers, at typical UTLS conditions, on the radiance
spectra observed by these simulated satellite instruments. We found a marked spectral
signature of these aerosol layers between 700 and 1200 cm-1, due to the absorption
bands of the sulphate and bi-sulphate ions and the undissociated sulphuric acid, with
absorption peaks at 1170 and 905 cm-1. Micro-windows with a sensitivity to chemical
and micro-physical properties of the sulphate aerosol layer are identified, and the
role of interfering species, and temperature and water vapour profile is discussed. |
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