NOAA Teacher at Sea
Aboard R/V Walton Smith
October 20 — 24, 2011
Mission: South Florida Bimonthly Regional Survey
Geographical Area: South Florida Coast and Gulf of Mexico
Date: 20 October 2011
Weather Data from the Bridge
Time: 11:39 AM
Wind direction: North-northwest
Wind velocity: 4.5 m/s
Air Temperature: 23 °C (75° F)
Clouds: Alto cumulus
Science and Technology Log
We left port today at about 6:30 AM, before the sun had even come up. We are headed out to the Florida Keys. The rain has stopped as well as the wind. We left Miami Harbor as the sun was coming up.
Our scientific research will take place along the Florida Keys, a chain of low-lying Islands that arc around the southern tip of Florida. The R/V Walton Smith will stop at predetermined stops and take measurements.
There are many science experiments happening on board. In each post, I will try to highlight a different experiment. I’ll start off with the CTD because it is the experiment that drives our schedule throughout our cruise.
The Conductivity, Temperature, & Depth Instrument. Everyone on board calls it the CTD for short. The CTD schedule is our game plan. At about every 3 -5 hours — night and day — we’ll cycle through a series 3-4 CTD drops.
On the bottom of the CTD are a number of instruments that give real-time data to a scientist on board the boat. The conductivity part of the instrument measures how much electricity passes through the sea water. Using a mathematical algorithm that takes in account temperature and how much current passes through the water, we can determine the density (salinity) of the water.
The top part of the CTD has 12 cylinders that can trap water. Those are the grey tubes you see in the picture to the left. There are lids on the top and bottom of each tube that can be closed with a remote control from inside the boat. In this way the scientists can take water samples from any depth of water.
So, when we arrive at one of these predetermined location we’ll lower the CTD.
Once the CTD is just below the surface of the water and everything checks out, the scientist will radio to the crane operator to lower the CTD to within a meter of the bottom of the ocean. That can be anywhere from 5 meters to over 100 down. As the CTD lowers, the scientist monitors the CTD instrument real-time readouts. Using a graph of the data, he or she will decide at which locations to close the cylinders on its return trip to the surface.
Once it surfaces, we’ll assist in placing the CTD back on the deck and securing it. We’ll then take water samples from the grey tubes. Those water samples will be analyzed in one of the laboratories on the boat. The water samples will show us chemical properties of the water.
Teamwork works! It takes a lot of teamwork to make things happen on board. Guiding the boat to the precise locations is the easy part for the crew. They have a GPS to help them do it. After they get there they have to maintain the location. That’s hard when currents, wind and waves, move the boat which is the size of a house. Then they delicately raise and lower the CTD.
If something happens, they also need to fix it. They can’t drive it to a repair shop. They have to fix things on the spot. During the night, some ropes from lobster traps got tangled into one of the propellers. One of the crew put on scuba gear, got in the water, and removed the ropes.
The group of scientists have been organized into a day shift from 7:00 AM to 7:00 PM and the other half is on the night shift for 7:00 PM to 7:00 AM. This can be uncomfortable to have to stay awake all night, but it also means they have to sleep during the day. The day shift will also have a heavier work load because there are additional experiments that have to be done during the sunshine.