Meredith Salmon: Xtreme XBTs, July 14, 2018

NOAA Teacher at Sea

Meredith Salmon

Aboard NOAA Ship Okeanos Explorer

July 12 – 31, 2018


Mission: Mapping Deep-Water Areas Southeast of Bermuda in Support of the Galway Statement on Atlantic Ocean Cooperation

Geographic Area:  Atlantic Ocean, south of Bermuda

Date: July 14, 2018

Weather Data from the Okeanos Explorer Bridge – July 14, 2018

Latitude: 28.58°N

Longitude: 65.48°W

Air Temperature: 27.4°C

Wind Speed:  13.96 knots

Conditions: Rain and clouds

Depth: 5183 meters


Science and Technology Log

Temperature and salinity are two main variables when determining the density of water. The density of water or any acoustic medium is a very important factor in determining the speed of sound in water. Therefore, temperature data collected by Expendable Bathythermograph (XBT) probes, as well as historical salinity profiles from the World Ocean Atlas, are used to create sound velocity profiles to use to correct for sound speed changes in the water column.

Expendable Bathythermograph (XBT) probes are devices that are used to measure water temperature as a function of depth. Small copper wires transmit the temperature data back to the ship where it is recorded and analyzed. At first, I was surprised to learn that temperature data is such an important component of multibeam mapping operations; however, I learned that scientists need to know how fast the sound waves emitted from the sonar unit travel through seawater. Since these probes are designed to fall at a determined rate, the depth of the probe can be inferred from the time it was launched. By plotting temperature as a function of depth, the scientists can get a picture of the temperature profile of the water.

On our expedition, we have been deploying XBTs on a schedule as the ship is making its way to the survey area. The XBT Launcher is connected to a deck box, which translates information to computer systems onboard so the data can be logged when the probes are deployed into the water. Aboard the Okeanos Explorer, up to 8 tubes can be loaded at one time and launched by scientists.

XBT closet in the Dry Lab
XBT closet in the Dry Lab


XBT Launcher
XBT Launcher on the Okeanos
xbt 2
Loading the XBT Launcher



xbt 1
Savannah and I after a successful XBT load


XBT Data
XBT Data from a launch aboard the Okeanos Explorer. The colors on the graph indicate the XBT number and the data is plotted on a temperature and depth scale.


 In addition to launching XBTs and collecting data, we completed a Daily Product so that we can communicate the data we have collected to anyone on shore. The Daily Products are completed not only to ensure that the hydrographic software systems are working correctly but to also inform the public our current location, where we have collected data, and if we are meeting the objectives of the mission. Once onshore, NOAA uses this information to analyze the quality of the data and use it for analysis for dive planning. In order to generate the Daily Field Products, we use hydrographic computer systems such as QPS Qimera for advanced multibeam bathymetry processing, Fledermaus for 4D geo-spatial processing, and Geocap Seafloor for digital terrain modeling. In addition, the Daily Field Products allow us to double check the quality of the data and search for any noise interferences due to the speed of the ship or the type of seafloor bottom (hard vs soft).


Personal Log

One of the coolest parts of learning aboard the Okeanos Explorer is the fact that I am a part of scientific exploration and discovery in real time.  Known as “America’s Ship for Ocean Exploration,” the Okeanos Explorer is the only federally funded U.S. ship assigned to systematically explore our largely unknown ocean for the sole purpose of discovery and the advancement of knowledge. This is the first U.S.-led mapping effort in support of the Galway Statement on Atlantic Ocean Cooperation and all of this information is going to be available for public use. Not only do I get the opportunity to be involved with “real-time” research, but I am also responsible for communicating this information to a variety of different parties on shore.

Being immersed in the “hands-on” science, learning from the survey techs and watch leads, and observing all of the work that is being done to collect, process, and analyze the data is a really exciting experience. I am definitely out of my element when it comes to the content since I do not have any prior experience with seafloor mapping, sonars, etc., but I am really enjoying playing the role as the “student” in this situation. There is definitely a lot to learn and I am trying to soak it all in!


Did You Know?

XBTs contain approximately 1,500 meters of copper wire that is as thin as a strand of hair!



Elizabeth Nyman: Tropical Storm Andrea Edition, June 6, 2013

NOAA Teacher at Sea
Elizabeth Nyman
Aboard NOAA Ship Pisces
May 28 – June 7, 2013

Mission: SEAMAP Reef Fish Survey
Geographical Area of Cruise: Gulf of Mexico
Date: June 6, 2013

Weather Data:
Wind Speed: 19.97 knots
Surface Water Temperature: 27.78 degrees Celsius
Air Temperature: 28.40 degrees Celsius
Barometric Pressure: 1010.40 mb

Science and Technology Log

The Pisces is on its way to port, having had to suspend operations in wake of the bad weather that has since become Tropical Storm Andrea. We were supposed to go into Mayport Naval Base, right outside of Jacksonville, FL, but due to the storm we have been redirected to Port Canaveral.

It’s been pretty rough out there! (Picture courtesy Ariane Frappier)

Despite all of this, we made the best of a bad situation. Even though we couldn’t do fishing or camera drops yesterday, we did still manage to get some data. We spent as much time as we could mapping the seafloor before we had to dodge the storm, and we took the time in the morning to do an XBT, an Expendable Bathythermograph.

You can use an XBT to get a temperature and depth reading for the water without having to actually stop the ship. A tube with a probe on it is attached to a launcher and is fired into the water. The probe has copper wire attached to it to send the data back to the ship.

So…you drop the probe, you get the readings, and at least you get some data even if you can’t stop the ship to send more delicate equipment down.

Launching probe…

Other than that, the past couple of days have been all about cleanup and dodging the storm. To a certain extent that makes the scientific posts a little quieter than usual, but it’s been a very interesting experience watching everyone work together to make sure that the scientists could get as much work done as possible without endangering the ship or its crew.

We didn’t get to do everything that we wanted to do on this leg of the trip, unfortunately. But we still got a lot accomplished, and I feel like it was just as interesting to see how everyone was able to react to the weather and still get their job done.

Personal Log

Whew! I didn’t imagine when I got on the Pisces in Tampa that I’d spend the last bit of the trip dodging the first named Tropical Storm of the Atlantic hurricane season. But I definitely have a greater appreciation that, with science as in all things, sometimes life does not go quite to plan.

If all goes to schedule, I will be leaving the Pisces tonight, for our detour into Port Canaveral. We had to stop working a day early, and we’ll end up arriving a day early and into a different port. My last day has mostly been spent trying to rearrange for my travel home from a new city and with assisting the science crew in cleaning up the lab spaces.

All data collection requires a certain amount of flexibility. I knew that already – social science data is notoriously difficult to collect – but the problems that I face in my work are quite different from these. When international relations scholars have trouble with data, it’s usually because of things like difficulties in getting governments and/or people to tell the truth, etc. But sometimes, as now, it’s because conditions make it unsafe to collect the data. We can’t send people into shooting wars to count casualties, and we can’t send scientists into a hurricane to count fish.

Science is a method, not a subject, and the scientific method is one wherein we all simply do our best with what we have. Science has been so profoundly influential because of the simple power of this process, testing over and over what we think to be true, so that we can learn if we are wrong. It’s true if you study fish, if you study policy, or if you study anything in between.

There are many things we’ve discovered about our oceans, and the fish and other creatures that inhabit them. But there are still many more things to learn. I’m glad that we have scientists like the ones I met on the Pisces out looking for our fish, and glad that NOAA, in conjunction with states and other government agencies like the Coast Guard, are looking out for our oceans.

My thanks go out to the entire crew of the Pisces, and the great people at the Teacher at Sea program, for letting me be a part of the process.

Did You Know?

NOAA is predicting a highly active hurricane season for the Atlantic this year. Stay safe!

Jacquelyn Hams: 7 November 2011

NOAA Teacher at Sea
Jackie Hams
Aboard R/V Roger Revelle
November 6 — December 10, 2011

Mission: Project DYNAMO
Geographical area of cruise: Leg 3, Eastern Indian Ocean
Date: November 7, 2011

Weather Data from the R/V Revelle Meteorological Stations

Time: 1100
Course on Ground
Wind Direction:   195.50
Wind Speed (m/s):   2.1
Air Temperature (C):  27.6
Relative Humidity:   81.7%
Dew Point: (C):   24.4
Precipitation (mm):   6.0

PAR (Photosynthetically Active Radiation) (microeinsteins): 517.4
Long Wave Radiation (w/m2): 405.3
Short Wave Radiation (w/m2): 60.5                                                                            

Surface Water Temperature (C): 28.7
Sound Velocity:  1540.6
Salinity (ppm): 32.45
Fluorometer (micrograms/l): 65.2
Dissolved Oxygen (mg/l): 3.6

Wave Data from WAMOS Xband radar

Wave Height (m) 1.6
Wave Period (s): 18.4
Wavelength (m):  312
Wave Direction:   2650

Science and Technology Log


Leg 3 of the Project DYNAMO research cruise began, on November 6, 2011 from Phuket, Thailand at approximately 1430. The DYNAMO Leg 3 research cruise consists of seven scientific groups conducting experiments in the following areas:

  • Surface Fluxes
  • Atmospheric Soundings
  • Aerosols
  • NOAA High Resolution Doppler LIDAR
  • TOGA Radar
  • Ocean Optics
  • Ocean Mixing

My primary role on this cruise is to work with the Ocean Mixing group led by Dr. Jim Moum from Oregon State University. The Ocean Mixing Group is responsible for sonar measurements of ocean current profiles, high frequency measurement of acoustic backscatter, turbulence/CTD profiling instruments and near surface CTD (Conductivity, Temperature, Depth) measurements. I will be working with other scientific groups as needed and have organized my Teacher at Sea blog to report on daily activities by science group.

Sampling Activities

We have been cruising for a couple of days to the sampling station in the eastern Indian Ocean and are still within the Exclusive Economic Zones (EEZ) of Thailand, India, and other countries.  Here is an interesting fact that I learned about the EEZ – it not only applies to resources, but also applies to data collection.  What this means to the R/V Revelle, is that the scientists cannot collect data until the ship clears the 200 nautical mile EEZ for the counties.  After clearing the EEZ, the science groups can begin data collection.

Atmospheric Soundings

Data collection began on the ship on November 8 and one of the first groups I observed was the Atmospheric Soundings group.  This group is responsible for launching radiosondes using helium balloons (weather balloons).  A radiosonde is an instrument that contains sensors to measure temperature, humidity, pressure, wind speed, and wind direction. Although the balloons can hold up to 200 cubic feet of helium, on this cruise, each balloon is filled with 30-35 cubic feet of helium.   As the radiosonde ascends, it transmits data to the ship for up to 1 ½ hours before the weather balloon bursts and falls into the ocean.  The weather balloons have been reaching an average altitude of 16 km before bursting. Approximately 260 weather balloons will be launched during Leg 3 of the cruise.

The Radiosonde

Watch the video clip below to watch the deployment of a weather balloon.

Computer screen shot of radiosonde data. Temperature is red, relative humidity in blue, wind speed is in green and wind direction is purple.

Ocean Mixing

The Ocean Mixing group began the deployment of XBTs (Expendable bathythermographs) on November 10, 2011. XBTs are torpedo shaped instruments which are lowered through the ocean to obtain temperature data. The XBT is attached to a handheld instrument for launching by a copper wire. Electronic readings are sent to the ship as the XBT descends in the ocean. When the XBT reaches 1,000 meters, the copper line is broken and the XBT is released and falls to the bottom on the ocean.


First step in getting the XBT ready.
Here I am getting ready to launch the XBT.
Launching the XBT
Computer screen shot of thermocline (change in temperature with depth) obtained from XBT instrument. The green shaded curve displays the historical record for comparison.


Personal Log

I arrived in Phuket, Thailand on November 3, 2011 after a 19-hour plane ride.  After dinner and a good night’s sleep, I went to the ship to get acquainted with my new home for the next 6 weeks.  Select the link below for a tour of the R/V Revelle.

Aboard the R/V Revelle in Phuket, Thailand

The Revelle sailed from Phuket on November 6.  As the ship sailed to station, I captured the beauty of the Indian Ocean.


A beautiful day on the Indian Ocean.

Jane Temoshok, October 2, 2001

NOAA Teacher at Sea
Jane Temoshok
Onboard NOAA Ship Ronald H. Brown
October 2 – 24, 2001

Mission: Eastern Pacific Investigation of Climate Processes
Geographical Area: Eastern Pacific
Date: October 2, 2001

Just got back from a fabulous C-130 flight! It was a long day but well worth it. The video and digital pictures will be amazing. They let me fly the plane!!!!! for real!!!! Then I dropped several air expendable bathythermographs (EXBT) – in other words big plastic tubes out of a hole in the floor of the plane.

The chief scientist, Nick Bond, also gave me a job to do which required using the onboard computers to note the exact time and longitude of each drop. The plane “porpoised” for 6 hours to just south of the equator. Porpoising means we flew at an altitude of 5000 feet for 7 min. and then descended to 100 feet! for 7 minutes and then back up to 5000 ft. Of course Dr. Kermond filmed everything so there will be lots to see. Everybody on board was very accommodating.

Please share my historic flight with my students tomorrow. I’m sure they will be impressed. We did fly over the RON BROWN – just barely because we were only at 100 ft! Then on our way back I was able to speak with Jennifer via the cockpit radio. Very exciting.

Keep in touch,