FALMOUTH FIELDCOURSE

Group 5

The views expressed are those of the individuals concerned and do not express the views of the University of Southampton or those of the National Oceanography Centre Southampton.

CTD

The CTD data from station 37 show a strong thermocline at the top of the water column, a second thermocline occurs at ~10m. The salinity is low at the surface which is likely to be the result of the rainfall experienced in the morning on which our measurements were taken; and the fresh water from the river mixing with the seawater as the tide went out. The salinity then increased with depth. Fluorescence was highly variable throughout the water column.

Station 37

R.V. Bill Conway

The CTD data from station 38 shows a decrease in temperature with depth, the thermoclines at this station are present but more gradual. The salinity increases with depth and shows variable throughout the water column. The fluorescence in variable with a small peak at 10m and at the seabed.

Station 38

Section 39

The CTD data from station 39 shows a mixed, saline environment. The temperature decreases slight in the upper part of the water column. Before remaining at ~16.2oC until about 12m where is decreases again dramatically. The fluorescence is variable throughout the water column, showing a small peak at 12m. Salinity is very low at the surface, this is likely to be caused by rainfall. Below 1m the salinity remain homogeneous.

The CTD data from station 40 show a homogeneity in salinity at about 33.6psu. The temperature remains between 16.2 and 16.4oC. The fluorescence is variable throughout the water column with a peak at ~8m and a second peak at ~14m. The unusual pattern seen in this figure is likely to the result of the CTD moving up in the water column part way through the profile, the most likely cause of this is wave action lifting the boat and CTD.

Station 40

Click below to see our physical data from offshore and the pontoon at King Harry Ferry

Click below for more data from the estuary

Winnie-the-Pooh

Temperature

The temperature of the surface water did not vary much from one site to another. This is due to the stations being located fairly close to each other and the weather staying consistent.

Salinity

There was little difference in the salinity at each station, the station with the highest salinity is O2 (31.5) this station was located further from the estuary and so a higher salinity would be expected. The salinity at Q2 is still high (29) this may be due to the incoming tide at that time, increasing the amount of salt water in the area.

Light Data

Whilst on Conway, a Secchi Disk was used to estimate the depth of the Euphotic zone. The Euphotic depth is three times the Secchi depth (the depth at which the Secchi disk can no longer be seen by the naked eye from the surface). The results were as follows: