RL Gammarus 9/83
Cruise summary report
|Ship name||RL Gammarus|
|Cruise period||1983-09-28 — 1983-09-30|
|Port of departure||Plymouth, United Kingdom|
|Port of return||Plymouth, United Kingdom|
|Objectives||Joint cruise with RL Tamaris.
Previous work in the Tamar Estuary showed that at neap tides, in one reach of the estuary, stratification gave way very rapidly to vertically homogeneous conditions. Thought that this might have been caused by breaking internal waves. The measurements were aimed at detecting these internal waves and measuring their characteristics.
Half hourly profiles of current speed and direction, salinity, temperature and suspended solids were taken through the water column. A CTD probe was suspended near the halocline. Measurements carried out over 1 tidal cycle. During the ebb tide the Gammarus carried out echo-sounding surveys from the Tamar Bridge to above Car Green.
Echo-sounding revealed the presence of several small fronts around and after high water. During the ebb tide internal waves appeared in the deep area near Car Green apparently caused by the topographic step at the upstrem end of the deep. The internal wave motions were apparent on the CTD records.
|Chief scientist||Keith Dyer (Institute of Oceanographic Sciences Taunton)|
|Cruise report||(0.06 MB)|
|Track charts||(0.02 MB)|
|CTD stations||Description: a number of CTD records were made during the tidal cycle (no. of samples not noted)|
|Subsurface temperature and salinity measurements||Description: Half hourly profiles taken through the water column during 1 tidal cycle|
|Current meters||Description: Half hourly profiles taken through the water column during 1 tidal cycle|
|Suspended matter||Description: Half hourly profiles taken through the water column during 1 tidal cycle|
|Geology and geophysics|
|Multi-beam echosounding||Description: Echosounding took place during the cruise and revealed several small fronts. No. of surveys not noted.|