Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurements
<p>We analyse the airborne measurements of above-cloud aerosols from the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign performed in Namibia during August and September 2017. The study aims to retrieve the aerosol above-cloud direct radiative effect (DRE) with we...
| Main Authors: | , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2021-05-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/21/8233/2021/acp-21-8233-2021.pdf |
| _version_ | 1818727860270006272 |
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| author | A. Chauvigné F. Waquet F. Auriol L. Blarel C. Delegove O. Dubovik C. Flamant M. Gaetani M. Gaetani M. Gaetani P. Goloub R. Loisil M. Mallet J.-M. Nicolas F. Parol F. Peers B. Torres P. Formenti |
| author_facet | A. Chauvigné F. Waquet F. Auriol L. Blarel C. Delegove O. Dubovik C. Flamant M. Gaetani M. Gaetani M. Gaetani P. Goloub R. Loisil M. Mallet J.-M. Nicolas F. Parol F. Peers B. Torres P. Formenti |
| author_sort | A. Chauvigné |
| collection | DOAJ |
| description | <p>We analyse the airborne measurements of above-cloud aerosols from
the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field
campaign performed in Namibia during August and September 2017. The study
aims to retrieve the aerosol above-cloud direct radiative effect (DRE) with
well-defined uncertainties. To improve the retrieval of the aerosol and
cloud properties, the airborne demonstrator of the Multi-Viewing,
Multi-Channel, Multi-Polarization (3MI) satellite instrument, called the
Observing System Including PolaRisation in the Solar Infrared Spectrum
(OSIRIS), was deployed on-board the SAFIRE (Service des Avions Français Instrumentés pour la Rechercheen Environnement) Falcon 20 aircraft during 10
flights performed over land, over the ocean, and along the Namibian coast.
The airborne instrument OSIRIS provides observations at high temporal and
spatial resolutions for aerosol above clouds (AACs) and cloud properties.
OSIRIS was supplemented with the Photomètre Léger Aéroporté
pour la surveillance des Masses d'Air version 2 (PLASMA2). The combined
airborne measurements allow, for the first time, the validation of AAC algorithms previously developed for satellite
measurements. The variations in the aerosol properties are consistent with
the different atmospheric circulation regimes observed during the
deployment. Airborne observations typically show strong aerosol optical
depth (AOD; up to 1.2 at 550 nm) of fine-mode particles from biomass burning (extinction Ångström exponent varying between 1.6 and 2.2), transported above bright stratocumulus decks (mean cloud top around 1 km above mean sea level), with cloud optical thickness (COT) up to 35 at 550 nm. The above-cloud visible AOD retrieved with OSIRIS agrees within 10 % of the PLASMA2 sun photometer measurements in the same environment.</p>
<p>The single scattering albedo (SSA) is one of the most influential parameters on the AAC DRE calculation that remains largely uncertain in models. During the AEROCLO-sA campaign, the average SSA obtained
by OSIRIS at 550 nm is 0.87, which is in agreement within 3 %, on average, with previous polarimetric-based satellite and airborne retrievals. The strong absorption of the biomass burning plumes in the visible range is generally
consistent with the observations from the Aerosol Robotic Network<span id="page8234"/> (AERONET)
ground-based sun photometers. This, however, shows a significant
increase in the particles' absorption at 440 nm in northern Namibia and
Angola, which indicates more absorbing organic species within the observed
smoke plumes. Biomass burning aerosols are also vertically collocated, with
significant amounts of water content up to the top of the plume at around 6 km height in our measurements.</p>
<p>The detailed characterization of aerosol and cloud properties, water vapour, and their uncertainties obtained from OSIRIS and PLASMA2 measurements allows us to study their impacts on the AAC DRE. The high-absorbing
load of AAC, combined with high cloud albedo, leads to unprecedented
DRE estimates, which are higher than previous satellite-based estimates. The average AAC DRE calculated from the airborne measurements in the visible range is <span class="inline-formula">+85</span> <span class="inline-formula">W m<sup>−2</sup></span> (standard deviation of 26 <span class="inline-formula">W m<sup>−2</sup></span>), with instantaneous
values up to <span class="inline-formula">+190</span> W m<span class="inline-formula"><sup>−2</sup></span> during intense events. These high DRE
values, associated with their uncertainties, have to be considered as new
upper cases in order to evaluate the ability of models to reproduce the radiative impact of the aerosols over the southeastern Atlantic region.</p> |
| first_indexed | 2024-12-17T22:20:48Z |
| format | Article |
| id | doaj.art-ecad28ed12d544e592c2a47f41253a30 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-17T22:20:48Z |
| publishDate | 2021-05-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-ecad28ed12d544e592c2a47f41253a302022-12-21T21:30:29ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242021-05-01218233825310.5194/acp-21-8233-2021Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurementsA. Chauvigné0F. Waquet1F. Auriol2L. Blarel3C. Delegove4O. Dubovik5C. Flamant6M. Gaetani7M. Gaetani8M. Gaetani9P. Goloub10R. Loisil11M. Mallet12J.-M. Nicolas13F. Parol14F. Peers15B. Torres16P. Formenti17CNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceCNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceCNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceCNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceCNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceCNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceLATMOS, UMR CNRS 8190, Sorbonne Université, Université Paris-Saclay, Institut Pierre Simon Laplace, Paris, FranceLATMOS, UMR CNRS 8190, Sorbonne Université, Université Paris-Saclay, Institut Pierre Simon Laplace, Paris, FranceClasse di Scienze Tecnologie e Società, Scuola Universitaria Superiore IUSS, Pavia, Italy.LISA, UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, FranceCNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceCNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceCNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, FranceCNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceCNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceCollege of Engineering, Mathematics, and Physical Sciences (CEMPS), University of Exeter, Exeter, EX4 4QE, UKCNRS, UMR 8518, Laboratoire d'Optique Atmosphérique (LOA), Université Lille, 59000 Lille, FranceLISA, UMR CNRS 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, France<p>We analyse the airborne measurements of above-cloud aerosols from the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign performed in Namibia during August and September 2017. The study aims to retrieve the aerosol above-cloud direct radiative effect (DRE) with well-defined uncertainties. To improve the retrieval of the aerosol and cloud properties, the airborne demonstrator of the Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) satellite instrument, called the Observing System Including PolaRisation in the Solar Infrared Spectrum (OSIRIS), was deployed on-board the SAFIRE (Service des Avions Français Instrumentés pour la Rechercheen Environnement) Falcon 20 aircraft during 10 flights performed over land, over the ocean, and along the Namibian coast. The airborne instrument OSIRIS provides observations at high temporal and spatial resolutions for aerosol above clouds (AACs) and cloud properties. OSIRIS was supplemented with the Photomètre Léger Aéroporté pour la surveillance des Masses d'Air version 2 (PLASMA2). The combined airborne measurements allow, for the first time, the validation of AAC algorithms previously developed for satellite measurements. The variations in the aerosol properties are consistent with the different atmospheric circulation regimes observed during the deployment. Airborne observations typically show strong aerosol optical depth (AOD; up to 1.2 at 550 nm) of fine-mode particles from biomass burning (extinction Ångström exponent varying between 1.6 and 2.2), transported above bright stratocumulus decks (mean cloud top around 1 km above mean sea level), with cloud optical thickness (COT) up to 35 at 550 nm. The above-cloud visible AOD retrieved with OSIRIS agrees within 10 % of the PLASMA2 sun photometer measurements in the same environment.</p> <p>The single scattering albedo (SSA) is one of the most influential parameters on the AAC DRE calculation that remains largely uncertain in models. During the AEROCLO-sA campaign, the average SSA obtained by OSIRIS at 550 nm is 0.87, which is in agreement within 3 %, on average, with previous polarimetric-based satellite and airborne retrievals. The strong absorption of the biomass burning plumes in the visible range is generally consistent with the observations from the Aerosol Robotic Network<span id="page8234"/> (AERONET) ground-based sun photometers. This, however, shows a significant increase in the particles' absorption at 440 nm in northern Namibia and Angola, which indicates more absorbing organic species within the observed smoke plumes. Biomass burning aerosols are also vertically collocated, with significant amounts of water content up to the top of the plume at around 6 km height in our measurements.</p> <p>The detailed characterization of aerosol and cloud properties, water vapour, and their uncertainties obtained from OSIRIS and PLASMA2 measurements allows us to study their impacts on the AAC DRE. The high-absorbing load of AAC, combined with high cloud albedo, leads to unprecedented DRE estimates, which are higher than previous satellite-based estimates. The average AAC DRE calculated from the airborne measurements in the visible range is <span class="inline-formula">+85</span> <span class="inline-formula">W m<sup>−2</sup></span> (standard deviation of 26 <span class="inline-formula">W m<sup>−2</sup></span>), with instantaneous values up to <span class="inline-formula">+190</span> W m<span class="inline-formula"><sup>−2</sup></span> during intense events. These high DRE values, associated with their uncertainties, have to be considered as new upper cases in order to evaluate the ability of models to reproduce the radiative impact of the aerosols over the southeastern Atlantic region.</p>https://acp.copernicus.org/articles/21/8233/2021/acp-21-8233-2021.pdf |
| spellingShingle | A. Chauvigné F. Waquet F. Auriol L. Blarel C. Delegove O. Dubovik C. Flamant M. Gaetani M. Gaetani M. Gaetani P. Goloub R. Loisil M. Mallet J.-M. Nicolas F. Parol F. Peers B. Torres P. Formenti Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurements Atmospheric Chemistry and Physics |
| title | Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurements |
| title_full | Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurements |
| title_fullStr | Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurements |
| title_full_unstemmed | Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurements |
| title_short | Aerosol above-cloud direct radiative effect and properties in the Namibian region during the AErosol, RadiatiOn, and CLOuds in southern Africa (AEROCLO-sA) field campaign – Multi-Viewing, Multi-Channel, Multi-Polarization (3MI) airborne simulator and sun photometer measurements |
| title_sort | aerosol above cloud direct radiative effect and properties in the namibian region during the aerosol radiation and clouds in southern africa aeroclo sa field campaign multi viewing multi channel multi polarization 3mi airborne simulator and sun photometer measurements |
| url | https://acp.copernicus.org/articles/21/8233/2021/acp-21-8233-2021.pdf |
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