It’s been an exciting evening as a storm has rolled into the area. We’ve had winds over 90mph, which is officially hurricane force wind on the Beaufort Scale. Although we’re perfectly safe on the ship, we’ve had to secure everything and most of the decks have been closed for safety (sorry, can’t get outside to take pictures… I don’t even think I’m strong enough to open the door against the winds). We’ve also had to temporarily stop using some of the equipment, like the CTD, that require a little calmer weather to operate. However, there are still other ways to collect data when the weather is up.

A Closer Look at XBTs

Closer look equipment
E., 4th grade, requests we take a closer look at the equipment we use on the ship.

Expendable bathytemperature probes, or expendable bathythermographs, are another piece of equipment that can be used by oceanographers to collect data on the temperature structure of the ocean with depth. Like a CTD, it descends taking information as it goes. However, unlike a CTD, it only collects information on temperature and is not retrievable.

XBT probe
The specially designed XBT probe used to collect temperature data with depth. Photo by Jessica K Robertson, courtesy of USGS.

The XBT probe is shot from a gun like device from the ship to the water. The probe is engineered to fall at a constant rate. As it falls it collects temperature data and relays that back to the ship through wires, still attached to the both ends of the device. Because the probe is specially designed to fall at known rate, depth can be inferred from the time since the probe was deployed. By plotting the temperature data from the probe as a function of depth, scientists can visualize the temperature profile of the water. The temperature profile can tell you valuable information about the water of an area and it can also be used to calculate the sound velocity (the speed at which sound will travel through water, which is impacted by the waters temperature and density) for the multi-beam.

XBT gun
The gun used to launch XBTs, to collect temperature and depth data, on the NBP.

Weather Summary
-10 C
Wind Speed
50 to 80 kts
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