Interpreting optical signals in shelf sea environments

Measurements of optically significant constituent (OSCs) concentrations in shelf seas can be used as sensitive indicators of ecosystem status and function. Measuring OSC concentrations is labour intensive and a method to improve data analysis would greatly enhance our ability to monitor shelf sea environments. One option is the inversion of optical signals to recover constituent concentrations, as instrumentation already exists for measuring optical properties in situ. The feasibility of inverting measurements of inherent optical properties (IOPs) to give constituent concentrations using linear matrix algebra is considered, as previous authors reported that this gave encouraging results. Two problems were identified when IOP inversion was tested using synthetic data. First, the results obtained degraded rapidly in response to increasing levels of noise. Second, the inversion process relied on accurate values for the specific inherent optical properties of the OSCs that were unlikely to be obtained in practice. A further difficulty was encountered in the long-term deployments of instrumentation for measuring IOPs, since the equipment proved to be very susceptible to fouling. Alternative methods for optical data analysis had to be proposed which were more resistant to noise and required fewer assumptions for analysis to be completed. Two promising lines of research were initiated. One involved combining IOP measurements with other available optical and hydrographic variables to study particle populations in Scottish sea lochs. The other employed signal processing techniques to derive information on sediment transport in Liverpool Bay from measurements of beam attenuation subjected to large amounts of biofouling. Both of these methods allow ecological information to be derived from optical data that has been gathered under sub-optimal conditions. They provide a foundation for the analysis of large scale optical data sets from planned ocean observing systems, which will deploy optical instruments on moorings, floats, ocean gliders and autonomous underwater vehicles.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral-pg

Grantor dc:publisher.institution

University of Strathclyde

Year dc:date.issued

2014

Author dc:creator

• Darley, Jennifer Mairi

DOI

10.48730/zka7-5905

Identifier

T13871

OAI identifier oai:identifier

oai:strathclyde:3j333230k