Automated processing of oceanic bubble images for measuring bubble size distributions underneath breaking waves

Al-Lashi, R.S. ORCID: 0000-0002-7775-8181, Gunn, S.R. and Czerski, H., 2016. Automated processing of oceanic bubble images for measuring bubble size distributions underneath breaking waves. Journal of Atmospheric and Oceanic Technology, 33 (8), pp. 1701-1714. ISSN 0739-0572

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Abstract

Accurate in situ measurements of oceanic bubble size distributions beneath breaking waves are needed for a better understanding of air–sea gas transfer and aerosol production processes. To achieve this goal, a novel high-resolution optical instrument for imaging oceanic bubbles was designed and built in 2013 for the High Wind Gas Exchange Study (HiWinGS) campaign in the North Atlantic Ocean. The instrument is able to operate autonomously and can continuously capture high-resolution images at 15 frames per second over an 8-h deployment. The large number of images means that it is essential to use an automated processing algorithm to process these images. This paper describes an automated algorithm for processing oceanic images based on a robust feature extraction technique. The main advantages of this robust algorithm are it is significantly less sensitive to the noise and insusceptible to the background changes in illumination, can extract circular bubbles as small as one pixel (approximately 20 μm) in radius accurately, has low computing time (approximately 5 seconds per image), and is simple to implement. The algorithm was successfully used to analyze a large number of images (850 000 images) from deployment in the North Atlantic Ocean as part of the HiWinGS campaign in 2013.

Item Type: Journal article
Publication Title: Journal of Atmospheric and Oceanic Technology
Creators: Al-Lashi, R.S., Gunn, S.R. and Czerski, H.
Publisher: American Meteorological Society
Date: 2016
Volume: 33
Number: 8
ISSN: 0739-0572
Identifiers:
NumberType
10.1175/JTECH-D-15-0222.1DOI
Divisions: Schools > School of Science and Technology
Depositing User: Linda Sullivan
Date Added: 12 Mar 2018 11:11
Last Modified: 12 Mar 2018 11:11
URI: http://irep.ntu.ac.uk/id/eprint/32911

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