University of Hertfordshire

By the same authors

Analysis and Modelling of TTL ice crystals based on in-situ measurement of scattering patterns

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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Original languageEnglish
Title of host publicationELS 2021. Book of Abstracts
Publication statusPublished - Jul 2021
Event19th Electromagnetic and Light Scattering Conference - online
Duration: 12 Jul 202116 Jul 2021
Conference number: XIX
https://els2021.physics.itmo.ru/

Conference

Conference19th Electromagnetic and Light Scattering Conference
Abbreviated titleELS-XIX
Period12/07/2116/07/21
Internet address

Abstract

The primary objective of this research is to analyse the scattering patterns of Tropical Tropopause Layer (TTL) ice crystals and find their characteristics like shape and size distributions. As cirrus is a high cloud, it plays a crucial role in the Earth-atmosphere radiation balance and by knowing the scattering properties
of ice crystals, their impact on the radiative balance can be estimated [1].
The in-situ data presented here was taken during the NERC and NASA Co-ordinated Airborne Studies in the Tropics and Airborne Tropical Tropopause Experiment (known as the CAST-ATTREX campaign) on 5th March 2015 at an altitude between 15-16km over the Eastern Pacific. During this flight, the 2D scattering patterns were captured by the Aerosol Ice Interface Transition Spectrometer (AIITS) [2] at the wavelength of 532nm.
Since manual analysis of scattering patterns is time-consuming, a Deep Learning code has been implemented to classify the scattering patterns (like rough, pristine and rounded hexagonal prisms). To speed up the process, the Deep Learning Network has been created using Transfer Learning (based on a
pre-trained network called GoogLeNet). After the analysis phase, the model crystals of specific types and sizes are generated using appropriate codes for light scattering computations (example: for rough crystals [3]). The scattering data of the model crystals are then simulated using a Beam Tracing Model (BTM) [4] [5] based on physical optics. By successive testing and further analysis, the crystal sizes can be estimated.
This research further helps to broaden the understanding of the general scattering properties of TTL ice crystals, to support climate modelling and contribute towards more accurate climate prediction.

Acknowledgment: E R M acknowledges the Met Office CASE Award.

References
[1] A. J. Baran. A review of the light scattering properties of cirrus. J. Quant. Spectrosc. Radiat. Transfer, 110:1239-1260, 2009.
[2] E. Hirst, C Stopford, P. H. Kaye, R. S. Greenaway and J D Dorsey. The Aerosol Ice Interface Transition Spectrometer – A new particle phase. ATTREX Science Meeting. Boulder, United States. 30 September 2013.
[3] C. T. Collier. Experimental and Computational Investigation into Light Scattering by Atmospheric Ice Crystals, PhD thesis, University of Hertfordshire, 2014.
[4] L. C. Taylor. A Beam Tracing Model for Electromagnetic Scattering by Atmospheric Ice Crystals, PhD thesis, University of Hertfordshire, 2016.
[5] E. Hesse, L. Taylor, C. Collier, A. Penttilä, T. Nousiainen and Z. Ulanowski. Discussion of a physical optics method and its application to absorbing smooth and slightly rough hexagonal prisms. J. Quant. Spectrosc. Radiat. Transfer, 218:54-67, 2018.

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