NOAA Teacher at Sea
Aboard NOAA Ship Thomas Jefferson
July 4 – July 22, 2022
Mission: Hydrographic Survey of Lake Erie
Geographic Area of Cruise: Lake Erie
Date: July 9, 2022
Weather Data from the Bridge
Latitude: 42ᵒ 08’3N
Longitude: 080ᵒ 16’2W
Sky Conditions: Few clouds
Wind Speed: 23.0 knots
Wind Direction: 030ᵒ NNE
Lake Temperature: 21.4 ᵒC
Wave Height: 4 -6 feet
Dry Bulb: 19.7 ᵒC
Wet Bulb: 16.6 ᵒC
Calculated Relative Humidity: 74%
Visibility: 10+ miles
Science and Technology Log
As explained in a previous blog, hydrographic survey uses sound energy. NOAA hydrographers use various tools to measure the speed of sound from the time it is sent out to the time it is received as an echo. Sound waves traveling through water of different density cause refraction (or bending) of the energy wave. The density of water is affected by the salinity, temperature, and depth of the water. Scientists need to measure these parameters (things) and then use this knowledge to correct the data depending upon the properties of the water the sound is traveling through. (If you have been following this blog, nothing so far is new.)
Today’s question is how is the temperature and salinity of a column of water measured? Hydrographers use different types of tools to measure the temperature, salinity, and water depth. As a group, these tools are called “sound velocity profilers”. A conductivity, temperature, and depth sensor (CTD) can measure these three things in a column of water and then it calculates the speed of sound in water using a formula called the Chen-Millero equation. (I do not claim at all to understand this equation!)
To make matters more interesting, there are two (I’m sure there are more than two, however, to simplify things, we will assume that there are only two) types of CTDs. One type is sent overboard when the ship is not moving. The other type can be used when the ship is moving. Using a CTD while the ship is moving is a great thing, because to get good data, CTD data must be taken frequently (every 1-4 hours) and this big ship is difficult to stop!
NOAA Ship Thomas Jefferson has both types of CTD sensors. They rely heavily on the type that can be used when the ship is moving. In fact, it is so important that we call it our MVP. This does not stand for Most Valuable Player – although it is extremely important! A moving vessel profiler (MVP) can be used to measure the water column when the ship is moving at regular survey speeds (8-10 knots). It kind of looks like a torpedo. The MVP system can be set up to drop to a given depth determined by the hydrographers in charge of the project – not to shallow & not too deep . . . just right.
It can be controlled remotely with a computer without needing someone to be on deck. Deploying the MVP is called a “cast”. The benefit of deploying a sound speed profiler like the MVP while the ship is moving is significant. It is a real time-saver! Surveyors do not need to stop the ship at regular intervals – this makes their time at sea much more efficient.
Yesterday, I got the opportunity to deploy the MVP. From the acquisition desk in the plot room, one first needs to get permission from the bridge (the “upstairs office” filled with people driving and navigating the ship), to take a “cast”. The conversation over the intercom goes something like this:
Laura: “Bridge, this is Survey.”
Bridge: “Go ahead Survey.”
Laura: “May I please take an MVP cast?”
Bridge: (If the area is clear of small boats and obstructions, they will respond,) “Go ahead Survey.”
Laura: (Once permission is granted, all you need to do is to push the “start” button. A lot of cable attached to the MVP automatically pays out and it drops to a set depth, a few meters above the bottom. Once this started to happen, I informed the Bridge by saying,) “Fish is away.”
Laura: (After reaching the designated depth, the cable drum turns quickly in reverse and hauls the MVP back up to near the surface. I finished by saying,) “Cast complete”.
I was a bit nervous talking to the bridge, but I think I did okay.
Meet the Crew
Sydney Catoire is a Lieutenant in the NOAA Corps. (More about the NOAA Corps in a future blog post.) She is an Operations Officer in Training (OPS IT). Sydney comes from a Navy family and grew up on Virginia Beach, VA. Ms. Catoire studied marine biology and mathematics at Old Dominion University in Norfolk, VA. Wanting to combine aspects of the Navy as well as work as a scientist led her to apply to the NOAA Corps. She received her Master of Science in Geospatial Information Sciences (GIS) while working for the Office of Coast Survey.
Why is your work important? The safety of navigation is our primary goal as hydrographers. We use the data to update nautical charts to make it safe to sail. The bathymetric products provided are open source (free for anyone to download and use) and are used for ocean and lake bed mapping. For example, the data can be used for tsunami storm surge modeling, coastal erosion, and habitat mapping. All this data is super critical and is used by a wide variety of scientific organizations and research institutions.
How will your job change once you become an Operations Officer (OPS)? She will still be involved with the day-to-day workings of the hydrographic survey, however, once she becomes an OPS, she will take a leadership role in the survey, assigning sheets (areas to survey), and mentoring sheet managers who develop the line plans (the path that the ship travels to complete the survey). In other words, she will decide on the most efficient methods to “mow the lawn.” She will also help to train junior officers, organize the processing of the data, and work directly with the Office of Coast Survey Hydrographic Division.
What is the thing about your job you like the most? She likes being on the bridge, navigating and driving the ship, as well as looking out the window for marine life – which lately has been very limited since we are sailing on the Great Lakes.
Tell us a few things about yourself outside of being an OPS IT. Sydney and her sister have a dog named, Max. She likes to scuba dive, hike, and hang out with her family and nephews when she is on shore.
Good Luck, Sydney as you strive to become an Operations Officer! For not originally knowing about this career path you sure have excelled and are an example for others with similar interests.
All the people on TJ have been very nice and hospitable. They freely answer my questions and are fun to hang out with during meals. There are three people, however, who are super important to the smooth sailing of TJ. They are the stewards, Ace & Brent and the Chief Steward, Miss Parker. I never imagined that the food would be so varied and tasty! A well-fed crew = a happy crew!
For the little Dawgs . . .
Q: Where is Dewey today? Hint: it is the back of the ship.
A: Dewey is sitting on the stern of the ship. The propellers are under the stern.
Well, that’s all for today. Spending time aboard NOAA Ship Thomas Jefferson has been a terrific learning experience. I am so thankful for the opportunity!