Shelf, shear and staircases: glider observations in the North Atlantic

Rollo, Callum (2022) Shelf, shear and staircases: glider observations in the North Atlantic. Doctoral thesis, University of East Anglia.

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Ocean gliders have established themselves as a key component of the Global Ocean Observing System. Gliders are particularly useful in shelf-break areas that cannot be surveyed by profiling floats, such as those of the Argo program. This thesis uses a legacy glider dataset to examine shelf break processes in an upwelling zone. This dataset covers two periods of upwelling over the NW Iberian margin in summer 2010. During this deployment, equatorward transport was maintained over the shelf for 70 days during one of the strongest upwelling seasons on record.

The use of gliders to collect temperature and salinity profiles for extended periods of time is well established. This thesis examines two new technologies that have recently been applied to gliders: acoustic Doppler current profilers (ADCPs) and automated classification algorithms. The integration of a 1~MHz ADCP into a Seaglider is described, along with the tests, trials, and results of four deployments. The challenges of this sensor integration are explored, with recommendations made for future use of the glider and suggested improvements to the ADCP. This work includes the production of a user manual for future users of the ADCP glider.

Using a dataset collected by three gliders in the tropical North Atlantic, a new algorithm for identifying thermohaline staircases in glider data is described. Applying this algorithm, over 14000 thermohaline steps are identified in profiles from the three gliders. It is hypothesised that the incidence of thermohaline staircases is limited by strong background gradients in conservative temperature and absolute salinity. Additionally, fast-response thermistor data are used to examine the sensitivity of automated thermohaline staircase classifiers to the vertical resolution of temperature and salinity profiles.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Chris White
Date Deposited: 23 Aug 2022 08:07
Last Modified: 23 Aug 2022 08:07


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