Observations of Dust Particle Orientation with the SolPol direct sun polarimeter
Abstract
Irregularly shaped dust particles in lofted atmospheric layers often present a preferential orientation which leads to the dichroic extinction of the forward-scattered light. This phenomenon was first observed relatively recently on atmospheric dust layers, through starlight observations [1]. The present study provides measurements of dichroic extinction of the solar light, due to its propagation through atmospheric dust layers, and uses these measurements as an indication of dust particle orientation. For this, we utilize unique measurements from the direct-sun Solar Polarimeter (SolPol) [2], kindly provided by the University of Hertfordshire, in the remote PANGEA station at the island of Antikythera, in Greece and in Cyprus. SolPol records the state of polarization of the direct sunlight at 550 nm, i.e. the total intensity I, Q/I and U/I (linear polarization) and V/I (circular polarization), with an accuracy of ~1% and precision of 105 ppm [2]. The instrument is mounted on an astronomical tracker in order to target directly the solar disc.
Data from the co-located AERONET sun-photometer and profiles from the PollyXT multiwavelength lidar are used to identify the dust optical depth and the dust layer vertical distribution. Preferred presentation type: eLightning/Oral [1] J. Bailey et al. (2008), The effect of airborne dust on astronomical polarization measurements, Mon. Not. R. Astron. Soc., Vol. 386, 1016-1022.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA210.0008D
- Keywords:
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- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES;
- 3360 Remote sensing;
- ATMOSPHERIC PROCESSES