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Results
CTD
Using the data collected by the CTD on the Conway research vessel we have plotted the temperature and salinity. The stations move consecutively inland in the estuary, with station 14 being at the mouth of the estuary, in close proximity to ‘Black Rock’. With the exception of station 15, the CTD profiles show a standard and fairly constant pattern of decreasing temperature with depth and increasing salinity with depth. Station 15 has an anomaly at around 1m depth however this could be due the the CTD sitting sat the surface and this closeness to the surface affecting the reading.
ADCP
Station 14 was furthest out to sea at 8:45 UTC. With high tide at 09:41 UTC, the tide was ebbing when these measurements were taken. Thus, higher velocities were observed in the surface of the water column as river water – which is less dense due to a lower salinity and so sits on top of the denser seawater below – was rushing out to sea.
Station 15, which was slightly more inland, up the Fal estuary, than Station 14, was taken at 9:55 UTC. Low tide was at 9:41 UTC, so these measurements were taken just after low tide. Near low tide velocities area very low as no water is moving. Following these measurements, the tide would begin to flood into the estuary.
Station 16 was next up the Fal estuary, at 10:48 UTC. With low tide at 9:41 UTC and high tide at 15:36 UTC, the tide was flooding into the estuary at this time. Here, slightly higher velocities were observed near the surface, so it might be that the tide had not yet picked up much momentum and was not yet flooding into the estuary.
Station 17 was furthest up the estuary and was collected at 11:16 UTC. High tide was at 15:36 UTC, and so these measurements were taken during flooding tide. Higher velocities are found at the bottom of the water column as the denser seawater is flooding into the estuary.
The views expressed here are not representative of the University of Southampton.