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Retrieval of SO2 from thermal infrared satellite measurements: correction procedures for the effects of volcanic ash (2009)

Corradini, S. ; Merucci, L. ; Prata, A. J.

EGU

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Publikationsdatum: 2017-04-04

Beschreibung: The simultaneous presence of SO2 and ash in a volcanic plume can lead to a significant error in the SO2 column abundance retrieval when multispectral Thermal InfraRed (TIR) data are used. The ash particles within the plume with effective radii from 1 to 10μm reduce the Top Of Atmosphere (TOA) radiance in the entire TIR spectral range, including the channels used for SO2 retrieval. The net effect is a significant SO2 overestimation. In this work the interference of ash is discussed and two correction procedures for satellite SO2 volcanic plume retrieval in the TIR spectral range are developed to achieve an higher computational speed and a better accuracy. The ash correction can be applied when the sensor spectral range includes the 7.3 and/or 8.7μm SO2 absorption bands, and the split window bands centered around 11 and 12μm required for ash retrieval. This allows the possibility of simultaneous estimation of both volcanic SO2 and ash in the same data set. The proposed ash correction procedures have been applied to the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Spin Enhanced Visible and Infrared Imager (SEVIRI) measurements. Data collected during the 24 November 2006 Mt. Etna eruption have been used to illustrate the technique. The SO2 and ash estimation is carried out by using a best weighted least squares fit method and the Brightness Temperature Difference (BTD) procedures, respectively. The simulated TOA radiance Look-Up Table (LUT) needed for the SO2 column abundance and the ash retrievals have been computed using the MODTRAN 4 Radiative Transfer Model. The results show the importance of the ash correction on SO2 retrievals at 8.7μm, where the corrected SO2 column abundance values are less than 50% of the uncorrected values. The ash correction on SO2 retrieval at 7.3μm is much less important and only significant for low SO2 column abundances. Results also show that the simplified and faster correction procedure underestimates the ash correction compared with the more time consuming but more accurate correction procedure. Such underestimation is greater for instruments having better ground pixel resolution, i.e. greater for MODIS than for SEVIRI.

Beschreibung: Published

Beschreibung: 177–191

Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani

Beschreibung: 1.10. TTC - Telerilevamento

Beschreibung: N/A or not JCR

Beschreibung: open

Schlagwort(e): volcanic ash retrieval ; volcanic so2 retrieval ; ash correction ; remote sensing ; MODIS ; SEVIRI ; Etna volcano ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

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Revision of Asiatic Poraneae (Convolvulaceae) \xe2\x80\x93 Cordisepalum, Dinetus, Duperreya, Porana, Poranopsis, and Tridynamia (2006)

Staples, G.W.

In: Blumea: Biodiversity, Evolution and Biogeography of Plants vol. 51 no. 3, pp. 403-492

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Publikationsdatum: 2024-01-12

Beschreibung: The genera Porana Burm.f. and Cordisepalum Verdc. are taxonomically revised. Five distinct groups of species segregated from Porana are here recognized at generic rank and the names Dinetus Sweet, Duperreya Gaudich., Poranopsis Roberty, and Tridynamia Gagnep., are taken up for four of them.\nPorana Burm.f., s.str., is herein restricted to two species. Cordisepalum is maintained as a genus distinct from, and closely related to, Poranopsis. All names are typified, selected taxa and characters are illustrated, and distribution maps are provided for all taxa. In total 20 species, one comprising two subspecies, are recognized. Two new species, Cordisepalum phalanthopetalum and Dinetus rhombicarpus, are described and illustrated. Names for Porana described from Africa, Madagascar, and the Americas are dealt with in the Species Exclusae. An index of numbered collections examined is provided.

Schlagwort(e): Convolvulaceae ; Cordisepalum ; Duperreya ; Dinetus ; Porana ; Poranopsis ; Tridynamia ; new species

Repository-Name: National Museum of Natural History, Netherlands

Materialart: info:eu-repo/semantics/article

Format: application/pdf