Using ocean gliders to understand the physical oceanography of Fitz Hugh Sound
| dc.contributor.author | Williamson, Martin | |
| dc.date.accessioned | 2026-05-11T15:14:31Z | |
| dc.date.available | 2026-05-11T15:14:31Z | |
| dc.date.issued | 2026 | |
| dc.description.abstract | Autonomous glider transects from Queen Charlotte Sound (QCS) into Fitz Hugh Sound (FHS) provide high resolution cross-sections of temperature, salinity, density, and oxygen that reveal the dynamics of deep-water renewal and vertical mixing in a deep-silled fjord on the central coast of British Columbia. Glider transects collected between March 2024 and August 2025 were analyzed alongside Hakai CTD surveys to document the timing, structure, and modification of renewal flows. Renewal primarily occurs as a summertime process, with dense QCS shelf water flowing over the Hakai Passage (HP) sill and flushing the FHS deep basin, with an upper layer of FHS water leaving through HP as a return flow. Renewal appears to occur over the HP sill as opposed to the wider southern sill. A temperature - salinity parameter space comparison suggests that weaker winter renewal can also occur, bringing higher oxygen water into the deep basin. Simple two-layer hydraulic control estimates give upper bound flow velocities of 0.6-0.7 ms−1 and volumetric fluxes of 3.6-4.2 × 104 m3 s−1, implying a characteristic deep basin flushing timescale of roughly 15-19 days during renewal conditions. Vertical diffusivity estimates based on conservative tracers yield values on the order of 10−3 m2 s−1, consistent with previous studies in similar British Columbia fjords and waterways. Although source waters on the shelf occasionally reached hypoxic concentrations during the study period, mixing over the sill and along the renewal flow path increased oxygen levels, preventing hypoxia in the FHS deep basin. These results highlight the role of sill mixing in buffering deep fjord basins from hypoxic shelf source water, but also suggest that future declines in oxygen on the QCS shelf could overcome this protection if water of lesser density becomes hypoxic. Supervisor: Jody Klymak | |
| dc.description.scholarlevel | Undergraduate | |
| dc.identifier.uri | https://hdl.handle.net/1828/23880 | |
| dc.language.iso | en | |
| dc.subject | deep water renewal | |
| dc.subject | fjord dynamics | |
| dc.subject | sill overflow | |
| dc.subject | vertical mixing | |
| dc.subject | Fitz Hugh Sound | |
| dc.subject | autonomous gliders | |
| dc.subject | oxygen transport | |
| dc.subject.department | School of Earth and Ocean Sciences | |
| dc.title | Using ocean gliders to understand the physical oceanography of Fitz Hugh Sound | |
| dc.type | Honours thesis |