Linear polarization signatures of atmospheric dust with the SolPol direct-sun polarimeter

<p>Dust particles in lofted atmospheric layers may present a preferential orientation, which could be detected from the resulting dichroic extinction of the transmitted sunlight. The first indications were provided relatively recently on atmospheric dust layers using passive polarimetry, when...

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Main Authors: V. Daskalopoulou, P. I. Raptis, A. Tsekeri, V. Amiridis, S. Kazadzis, Z. Ulanowski, V. Charmandaris, K. Tassis, W. Martin
Format: Article
Language:English
Published: Copernicus Publications 2023-10-01
Series:Atmospheric Measurement Techniques
Online Access:https://amt.copernicus.org/articles/16/4529/2023/amt-16-4529-2023.pdf
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author V. Daskalopoulou
V. Daskalopoulou
P. I. Raptis
A. Tsekeri
V. Amiridis
S. Kazadzis
Z. Ulanowski
Z. Ulanowski
V. Charmandaris
V. Charmandaris
V. Charmandaris
K. Tassis
K. Tassis
W. Martin
author_facet V. Daskalopoulou
V. Daskalopoulou
P. I. Raptis
A. Tsekeri
V. Amiridis
S. Kazadzis
Z. Ulanowski
Z. Ulanowski
V. Charmandaris
V. Charmandaris
V. Charmandaris
K. Tassis
K. Tassis
W. Martin
author_sort V. Daskalopoulou
collection DOAJ
description <p>Dust particles in lofted atmospheric layers may present a preferential orientation, which could be detected from the resulting dichroic extinction of the transmitted sunlight. The first indications were provided relatively recently on atmospheric dust layers using passive polarimetry, when astronomical starlight observations of known polarization were found to exhibit an excess in linear polarization, during desert dust events that reached the observational site. We revisit the previous observational methodology by targeting dichroic extinction of transmitted sunlight through extensive atmospheric dust layers utilizing a direct-sun polarimeter, which is capable to continuously monitor the polarization of elevated aerosol layers. In this study, we present the unique observations from the Solar Polarimeter (SolPol) for different periods within 2 years, when the instrument was installed in the remote monitoring station of PANGEA – the PANhellenic GEophysical observatory of Antikythera – in Greece. SolPol records polarization, providing all four Stokes parameters, at a default wavelength band centred at 550 nm with a detection limit of 10<span class="inline-formula"><sup>−7</sup></span>.</p> <p>We, overall, report on detected increasing trends of linear polarization, reaching up to 700 parts per million, when the instrument is targeting away from its zenith and direct sunlight propagates through dust concentrations over the observatory. This distinct behaviour is absent on measurements we acquire on days with lack of dust particle concentrations and in general of low aerosol content. Moreover, we investigate the dependence of the degree of linear polarization on the layers' optical depth under various dust loads and solar zenith angles and attempt to interpret these observations as an indication of dust particles being preferentially aligned in the Earth's atmosphere.</p>
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spelling doaj.art-aaab7a9c60734d92915f31c28adbc7ab2023-10-12T08:19:24ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482023-10-01164529455010.5194/amt-16-4529-2023Linear polarization signatures of atmospheric dust with the SolPol direct-sun polarimeterV. Daskalopoulou0V. Daskalopoulou1P. I. Raptis2A. Tsekeri3V. Amiridis4S. Kazadzis5Z. Ulanowski6Z. Ulanowski7V. Charmandaris8V. Charmandaris9V. Charmandaris10K. Tassis11K. Tassis12W. Martin13Department of Physics, University of Crete, Heraklion 70013, GreeceInstitute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, Athens 15236, GreeceInstitute for Environmental Research and Sustainable Development, National Observatory of Athens, Athens 15236, GreeceInstitute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, Athens 15236, GreeceInstitute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, Athens 15236, GreecePhysikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Davos 7260, SwitzerlandDepartment of Earth and Environmental Sciences, University of Manchester, Manchester M13 9PL, UKBritish Antarctic Survey, NERC, Cambridge CB3 0ET, UKDepartment of Physics, University of Crete, Heraklion 70013, GreeceInstitute of Astrophysics, Foundation for Research and Technology – Hellas, Heraklion 70013, GreeceEuropean University Cyprus, Diogenes St., Engomi, Nicosia 1516, CyprusDepartment of Physics, University of Crete, Heraklion 70013, GreeceInstitute of Astrophysics, Foundation for Research and Technology – Hellas, Heraklion 70013, GreeceCentre for Atmospheric and Climate Physics Research, University of Hertfordshire, Hatfield AL10 9AB, UK<p>Dust particles in lofted atmospheric layers may present a preferential orientation, which could be detected from the resulting dichroic extinction of the transmitted sunlight. The first indications were provided relatively recently on atmospheric dust layers using passive polarimetry, when astronomical starlight observations of known polarization were found to exhibit an excess in linear polarization, during desert dust events that reached the observational site. We revisit the previous observational methodology by targeting dichroic extinction of transmitted sunlight through extensive atmospheric dust layers utilizing a direct-sun polarimeter, which is capable to continuously monitor the polarization of elevated aerosol layers. In this study, we present the unique observations from the Solar Polarimeter (SolPol) for different periods within 2 years, when the instrument was installed in the remote monitoring station of PANGEA – the PANhellenic GEophysical observatory of Antikythera – in Greece. SolPol records polarization, providing all four Stokes parameters, at a default wavelength band centred at 550 nm with a detection limit of 10<span class="inline-formula"><sup>−7</sup></span>.</p> <p>We, overall, report on detected increasing trends of linear polarization, reaching up to 700 parts per million, when the instrument is targeting away from its zenith and direct sunlight propagates through dust concentrations over the observatory. This distinct behaviour is absent on measurements we acquire on days with lack of dust particle concentrations and in general of low aerosol content. Moreover, we investigate the dependence of the degree of linear polarization on the layers' optical depth under various dust loads and solar zenith angles and attempt to interpret these observations as an indication of dust particles being preferentially aligned in the Earth's atmosphere.</p>https://amt.copernicus.org/articles/16/4529/2023/amt-16-4529-2023.pdf
spellingShingle V. Daskalopoulou
V. Daskalopoulou
P. I. Raptis
A. Tsekeri
V. Amiridis
S. Kazadzis
Z. Ulanowski
Z. Ulanowski
V. Charmandaris
V. Charmandaris
V. Charmandaris
K. Tassis
K. Tassis
W. Martin
Linear polarization signatures of atmospheric dust with the SolPol direct-sun polarimeter
Atmospheric Measurement Techniques
title Linear polarization signatures of atmospheric dust with the SolPol direct-sun polarimeter
title_full Linear polarization signatures of atmospheric dust with the SolPol direct-sun polarimeter
title_fullStr Linear polarization signatures of atmospheric dust with the SolPol direct-sun polarimeter
title_full_unstemmed Linear polarization signatures of atmospheric dust with the SolPol direct-sun polarimeter
title_short Linear polarization signatures of atmospheric dust with the SolPol direct-sun polarimeter
title_sort linear polarization signatures of atmospheric dust with the solpol direct sun polarimeter
url https://amt.copernicus.org/articles/16/4529/2023/amt-16-4529-2023.pdf
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