Southampton University Falmouth 2015

Group 13

© B Carter

Disclaimer: The views and opinions expressed are those of the individual and not necessarily those of the University of Southampton or the National Oceanography Centre, Southampton.

Physical Analysis

Figure 29: ADCP and CTD screens

Figure 28: Group 13 with CTD screens

© J Tinkler

© J Tinkler

Figure 35: CTD profile at station 73a

Figure 30: CTD profile at Station 68

Figure 31: CTD profile at Station 69

Figure 32: CTD profile at station 70

Figure 33: CTD profile at station 71

Figure 34: CTD profile at station 72

Station 68: We see the thermocline at approximately 18m. There is a temperature range of 4.6˚C and a minimum at 60.8m of 11.8 ˚C. There is little range in salinity. It reaches a minimum 35.1 at 14.5m and a maximum of 35.3 at 25m.

Station 69: we see the thermocline a little shallower at approximately 10m, it then drops quite quickly until it levels out at 38m. There is a temperature range of 5.1˚C. Again the salinity has little range and stays around 35.3. However at the thermocline it drops down to 34.9 and jumps to 35.4.

Station 70: The thermocline is found at approximately 15m. There is a temperature range of 4.2˚C. There is a very small salinity range at this station of 0.4. The salinity reaches its maximum and minimum at the thermocline.

Station 71: The thermocline is less clear at this station. There is a temperature range of 3.4˚C. There is an especially small salinity range at this station of only 0.26. The salinity fluctuates throughout this profile it is at its minimum at the surface (35.12) and its maximum at 18m (35.38).

Station 72: The thermocline is at approximately 12m. There is a temperature range of 4.6˚C. The salinity is at its maximum at 2m (35.66). The salinity levels out around 35m (35.3).

Station 73a: The thermocline is at approximately 15m. There is a temperature range of 4.9˚C. The salinity is at its maximum at 17 (35.35).

ADCP data

There are two main flow distributions present from the offshore ADCP data. However, the ADCP was unable to make readings to the full depths across some of the transects as the vessel was travelling at too great a velocity. In the morning up to 12:22 the flow is greater in the middle of the water column and lower at the atmosphere-sea interface and the sea-seabed interface. This could be because of friction at the interface. There are five transects with this example and an example of this distribution is transect 68:

Start:

Time: 08:26:23

Latitude: 50o 5.616948’ N

Longitude: 004o 51.899615’ W

Finish:

Time: 08:44:34

Latitude: 50o 5.484652’ N

Longitude: 004o 51.832669’ W

After 13:12 the flow is greatest at the surface and decreases as you go down the water column. This will be because the wind increased in the afternoon which would increase the flow velocity at the surface. The flow in the middle of the water column would remain similar to the flow in the morning as it will be too deep to be significantly affected by the wind. The flow velocity will be lowest at the seabed due to the waters friction with the seabed and the increased pressure and density of the water at the seabed. There were 5 transects with this distribution and one example of this distribution is transect 73.

Start:

Time: 13:17:11

Latitude: 500 16.333813’ N

Longitude: 004o 22.691515’ W

Finish:

Time: 13:24:30

Latitude:50o 16.360521’ N

Longitude: 004o 22.812270’ W

Figure 36 -ADCP transect showing fastest flow in centre of water column

Figure 37 - ADCP transect showing decreasing velocities as you descend through the water column