Mixed or Layers

In Activities 4 & 5, you will research how one event affected oceanographic conditions at two Gulf of Maine sites.

#4) Calculate the thermocline strength before and after an Autumn storm event.

Downland & print “Data Tracking Sheet” (PDF format). For these stations, write down the average water temperature:

  1. ABOVE the main thermocline; and
  2. The first 20 meters BELOW the main thermocline:

Station 4 | and | Station 8 |

NOTE: You’ll have sets of numbers for BEFORE the storm (red line on graph) and AFTER the storm (purple line on graph).

  • Note these depths under “Temp. ABOVE Thermocline” and “Temp. BELOW Thermocline.”
  • Based on these calculations, classify each thermocline as follows:
    • Temperature difference is less or equal to than 4 degreesCelsius: WEAK
    • Temperature difference is greater than 4 degrees Celsius: STRONG
  • In the shown example above, the strength of the thermocline is STRONG (14°C – 8°C = 6°C).

#5) Discover whether a storm event can change ocean layering.

Step A: Link to plots of Air TemperatureBarometric Pressure and Wind Speedduring our Autumn cruise. The dates when we were collected data at Stations 4 and 8 are shown.

  • Use these data plots to discuss the storm event itself:
    • How windy was it? (Note that 25 meters per second is about 50 miles per hour).
    • What was the barometric pressure like during the storm?
    • What happened to the AIR temperature during the storm?

Step B: Look at the following data for Stations 4 and 8 during Autumn:

  • At Station 4, did the salinity profile change after the storm? What about the fluorescence profiles?
  • At Station 8, did the salinity profile change after the storm? What about the fluorescence profiles?
  • Did one station experience significantly more change the the other? Can you guess why or why not?
  • In general, which factor (i.e., temperature, salinity or fluorescence) was most affected by the storm? Why do you think this is so?