NOAA Teacher At Sea
Aboard NOAA Ship Thomas Jefferson
June 20- July 1, 2022
Mission: Hydrographic Survey
Geographic Area of Cruise: Lake Erie
Date: Tuesday, June 21, 2022
Latitude: 41° 31′ 52 N
Longitude: 82° 12′ 00 W
Altitude: 138 m
Weather Data from Bridge
Wind Speed: 21 kts
Surface Water Temperature: 22 °C
Air Temperature (Dry Bulb Temperature): 23.5 °C
Wet Bulb Temperature: 22.9 °C
Relative Humidity: 55 %
Barometric Pressure: 25.5 in
Science and Technology Log
Learning is in full swing on NOAA Ship Thomas Jefferson. Previously, I talked about the multibeam sonar that the ship uses to map the bottom of Lake Erie. I also talked about how this technology related to other real-world applications. I hope I inspired you there.
Now, I am going to talk about another technology that Thomas Jefferson uses- side scan sonar. The technology basically detects and creates images of objects on the lake/ocean floor. The ship concurrently uses both technologies. Side scan sonar technology takes images of the bottom of Lake Erie and multibeam sonar records the depth; the seafloor/lakebed data is also known as bathymetry. For instance, if there is a big obstacle or a shipwreck in Lake Erie, side scan sonar would show an image. Then, multibeam sonar would be used to get the depth of the obstacle.
How does side scan sonar work differently than multibeam sonar?
If you remember from my previous post, multibeam sonar sends sound waves down towards the lake bottom. Side scan sonar also sends out sound waves, but from both sides of its transducer, sweeping the seafloor like a fan-shaped beam of a flashlight. So, the data needs to be composed of both the image and depth which allows a more comprehensive map of the seafloor.
A third technology used with the multibeam and side scan sonars is called “moving vessel profiler (MVP)”. The MVP is similar to a conductivity, temperature, depth (CTD) cast as it collects electrical conductivity, temperature, and pressure (to get depth) of water. The benefit of the MVP is that the ship can continue moving and receive sound speed information, rather than coming to a complete stop to deploy a CTD. This improves efficiency, allowing the ship to collect more data.
The MVP is a metal structure that looks like a big fish- also known as a towfish- located at the tail of the ship. As the ship moves, the instrument trails behind it, about a meter below the water’s surface. Sensors to collect sound speed information are located inside the towfish. When the MVP is deployed, the towfish free falls to the lake/sea bottom, before being automatically brought to the surface by the ship’s winch. Then, the ship receives a profile of the water column’s salinity and temperature, and can apply the sound speed measurements to the multibeam data. This information is critical for ensuring acquired depth measurements are in the proper location on the lakebed/seafloor. For the sake of Thomas Jefferson’s mission, CTD data is enough to process multibeam. However, other research vessels could have additional sensors within the MVP including some that measure chemical and biological parameters such as dissolved oxygen and chlorophyll fluorescence, etc.
The MVP Training; Deployment of Towfish
Let’s elaborate a few science concepts here. Conductivity is a measure of water’s capability to pass electrical flow. It does that based on how many ions are in the water. Therefore, the more ions present, the higher the conductivity of water. Ions are mainly coming from dissolved salts and inorganic materials such as alkalis, chlorides, sulfides, and carbonate compounds. These ions (positive/negative charges) in the water create electric current, so it conducts electricity.
Using the concept of electrical properties of dissolved salts, scientists measure the electrical conductivity of water so that they know the amount of salt present in the water (salinity). As you would expect, Lake Erie is freshwater so salinity is essentially zero.
Conductivity is one of the most useful and commonly measured water quality parameters. Knowing changes of dissolved solids in the water is an indicator of change in a water system. Different life forms adapted to different salt concentrations in the water. Even a slight change to this parameter could have a disastrous effect on life forms in water which creates a cascade of effects in other systems.
It was my second day on ship, and also the summer solstice. Today, sunrise was at 5:55 am and sunset was at 9:07 pm. It was the longest day for Lake Erie, indeed! It was also World Hydrography Day, yay! I am honored and humbled to be a part of Thomas Jefferson’s crew and to be the first Teacher at Sea on Great Lakes, especially on the longest day of the year and on World Hydrography Day in Lake Erie!
After eating my breakfast, I headed to MVP training. It sounded complicated but once I was on it, it was easy to navigate the instrument at sea. Then, I was called for my first boat ride. The ship has several “small” boats to assist in data collection, and they are beneficial for transiting and collecting bathymetry in more shallow places on the water. We had three people on the boat, doing side scan data collection closer to the shorelines. We also did several CTD casts, for nearshore sound speed profiles! On the ship the MVP can collect CTD data more frequently, whereas on the boat, we had to manually put it in the water every 4 hours. The boat was amazing, and I felt like I was on a private vacation boat! However, in this case, I was not only having fun, but also doing citizen science. I learned so much about the side scan, why it is used, and how the data helps the overall mission of Thomas Jefferson.
In this personal blog, instead of just including all the cool things I have done on the ship, I want to share some of my opinions about what I feel about my experience so far.
I would say about one-third of the crew on the ship are women in their twenties and thirties. Many of them are NOAA Corps officers and survey technicians/scientists. What an inspiring environment for women in STEM! They are involved in everything from navigating the ship to collecting data, from driving the boat to doing hands-on activities. I strongly believe that our female crew members are such an inspiration for future generations who will make things better!
Another feeling I have is how people are passionate about what they do. For example, I never thought a Commanding Officer (CO) and Executive Officer (XO) would be so friendly and approachable . I’m glad Thomas Jefferson has a great executive team. I’ve been having great conversations during lunch or any place I go on the ship. In one of our lovely conversations, both CO and XO strongly encouraged me to bring my students to visit the ship to give a tour. I said “This is exactly what I am here for!” I want to bring back my experiences to my school and community, and I can’t wait to bring them to the ship! They will absolutely love it.
In my last note, I should say that people who choose their careers based on their passion, are the ones who are successful, and also constantly inspire others to follow their footsteps. I have seen this in many professions across different fields. It is especially obvious when you have a public service job like educators, officers, doctors… You always have to do more than what your job asks you to do. If this is not something you are passionate about then the job becomes torture rather than enjoying.
Here, on Thomas Jefferson, seeing these men and women on a research vessel, working tirelessly around the clock, collecting data, once again proved to me that you have to be passionate about what you do.
Anyway, I think it is enough for me to stop talking about what I feel. But, you should know this – always follow your passion. That’s when you will find your real purpose in life.
Do you know?
- The National Oceanic and Atmospheric Administration Commissioned Officer Corps, known as the NOAA Corps, is one of the eight federal uniformed services of the United States. Those officers are made up of scientifically and technically trained officers. It is one of two U.S. uniformed services (the other being the U.S. Public Health Service Commissioned Corps) that consists only of commissioned officers, with no enlisted or warrant officer ranks.
- To become a NOAA Corps officer, applicants must hold a baccalaureate degree, preferably in a major course of study related to NOAA’s scientific or technical activities. When selected for appointment, officer candidates must satisfactorily pass a mental and physical examination. For more information check out NOAA Corps eligibility requirements here.