Presentation Abstract

The Strait of Georgia is a complex system of basins and waterways within the Salish Sea that receives the majority of Greater Vancouver’s wastewater via riverine input and effluent outfalls. It can be nominally divided into three constituent water masses: (1) a riverine surface layer; (2) a deep oceanic layer; and (3) an intermediate layer, composed of a mixture of the surface and deep waters. The intermediate water (IW) layer is the largest layer volumetrically and a primary component of the region’s subsurface estuarine circulation, yet a comprehensive understanding of the system has proved challenging. Here, we use two methods to assess the circulation pathways. The first method uses a synthesis of hydrographic observations to determine seasonal cycles in IW mass characteristics and exploits the spatial variation in seasonal cycle phase and amplitude to age the water mass, infer circulation and mixing, and understand the transport and eventual fate of IW in the Strait of Georgia. The second method uses particle tracking techniques implemented using SalishSeaCast model velocity outputs to similar effect. The IW circulation is found to be more complex than previously anticipated, with a direct alteration of circulation via inputs to the north of the region, a distinct cyclonic flow in the primary basin, and a strong inflowing boundary current on the eastern shores. Furthermore, we find evidence that wastewater tracer concentrations downstream of major effluent outfalls are consistent with our inferences of IW pathways.

Session Title

Track: Contaminants, Plastics, Microplastics, Toxicology & Stormwater – Posters

Conference Track

Contaminants, Plastics, Microplastics, Toxicology & Stormwater

Conference Name

Salish Sea Ecosystem Conference (2020 : Online)

Document Type

Event

SSEC Identifier

2020_abstractID_4627

Start Date

21-4-2020 9:00 AM

End Date

22-4-2020 4:45 PM

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

Language

English

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Apr 21st, 9:00 AM Apr 22nd, 4:45 PM

Using seasonality and particle tracking to trace Intermediate Water in the Strait of Georgia

The Strait of Georgia is a complex system of basins and waterways within the Salish Sea that receives the majority of Greater Vancouver’s wastewater via riverine input and effluent outfalls. It can be nominally divided into three constituent water masses: (1) a riverine surface layer; (2) a deep oceanic layer; and (3) an intermediate layer, composed of a mixture of the surface and deep waters. The intermediate water (IW) layer is the largest layer volumetrically and a primary component of the region’s subsurface estuarine circulation, yet a comprehensive understanding of the system has proved challenging. Here, we use two methods to assess the circulation pathways. The first method uses a synthesis of hydrographic observations to determine seasonal cycles in IW mass characteristics and exploits the spatial variation in seasonal cycle phase and amplitude to age the water mass, infer circulation and mixing, and understand the transport and eventual fate of IW in the Strait of Georgia. The second method uses particle tracking techniques implemented using SalishSeaCast model velocity outputs to similar effect. The IW circulation is found to be more complex than previously anticipated, with a direct alteration of circulation via inputs to the north of the region, a distinct cyclonic flow in the primary basin, and a strong inflowing boundary current on the eastern shores. Furthermore, we find evidence that wastewater tracer concentrations downstream of major effluent outfalls are consistent with our inferences of IW pathways.