Unit:
Κατεύθυνση Φυσική Περιβάλλοντος (ΕΦΑΡΜΟΣΜΕΝΗ ΦΥΣΙΚΗ)Library of the School of Science
Supervisors info:
Γιαννακάκη Ελένη, Λέκτορας, Τμήμα Φυσικής, ΕΚΠΑ
Φλόκα Ελένη, Αναπληρωτής, Τμήμα Φυσικής, ΕΚΠΑ
Αμοιρίδης Βασίλειος, Ερευνητής Α' Βαθμίδας, Εθνικό Αστεροσκοπείο Αθηνών
Original Title:
Χαρακτηρισμός των υπερυψωμένων στρωματώσεων που ανιχνεύθηκαν κατά την διάρκεια της πειραματικής εκστρατείας Pre-TECT
Translated title:
Characterization of the elevated aerosol layers detected during the Pre-TECT experimental campaign
Summary:
In this master thesis we present measurements of elevated, aged smoke layers originating from large scale fires in both Europe and Canada. The elevated layers were detected with the PollyXT LiDAR system of the National Observatory of Athens. PollyXT emits linearly polarized radiation at three wavelengths (355, 532 and 1064nm) and provides vertical profiles of the backscatter and extinction coefficient, LiDAR ratio, depolarization ratio (PLDR) and the Angstrom exponent, all important characteristics of the particles in terms of their optical properties. For the case studies presented, the PLDR values are found to be larger than typical values for smoke while there is also a strong wavelength dependence between 355 and 532nm. To interpret these results, simulations with the T-matrix scattering model were utilized with the assumption of near spherical particles. A range of different values of the complex refractive index, particle size and sphericity were used to conclude to the optimum combination of microphysical and geometrical properties that can reproduce our measurements. We conclude that the observed PLDR values can be simulated by the scattering model with the assumption of spheroids while this is not the case for more complicated shapes. This characteristic of smoke particles can potentially affect calculations referring to their interaction with radiation.
Main subject category:
Science
Keywords:
LiDAR, Smoke, Depolarization, Scattering, Radiation
File:
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Διπλωματικη κεφ 1-4_v02 (Autosaved)1.pdf
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