A Sea of Sondes

Air & Sea Chronicles

Editor's note: Air & Sea Chronicles is NOAA's blog series documenting the ATOMIC mission in Barbados. This is the third post from Janet Intrieri, a research scientist from NOAA's Earth System Research Lab Physical Sciences Division, who gives us a recap of a week releasing weather balloons on the NOAA Ship Ronald H. Brown.

On January 23, we launched our 97th weather balloon – and the last one on this first ATOMIC leg (we will probably launch another 97 on the next leg too!). To commemorate the last balloon of Leg One, we all signed the balloon (Photo 1) before we sent it into the sky (Photo 2).

Photo 1

Final balloon of Leg One…signed, sealed and delivered into the atmosphere (Photo by Richard Marchbanks)

So, what does launching a weather balloon, every four hours, around the clock, every day, from the middle of the ocean entail?  Well, in general, it involves initializing the sensor package with a computer on the ground, filling a balloon with helium, and then releasing it off the back of the ship (called the fantail). And last, but not least, it’s made possible by a team of dedicated folks (from Oregon State University, NOAA, the Barbadian Coast Guard, Scripps Institute of Oceanography, Caribbean Institute for Meteorology and Hydrology, and Woods Hole Oceanographic Institution – Photo 3)!

How high do they go?

The balloons usually go to 25 kilometers (about 15.5 miles) high, all the way through the part of the atmosphere that accounts for our weather. Our record height from the ship was recorded at 27.68 km (about 17.2 miles), about three times as high as a commercial jet flies. Radiosondes can take data for about two hours as they ascend and drift with the winds. The balloon expands as it rises, reaches its maximum height and pops, then continues to take data as it descends.

Photo 3

The balloon launching team (Photo by Richard Marchbanks)

Why do we release balloons?

Weather balloons are released every day (usually twice a day) all over the world (around 1,000 each day). In the U.S., NOAA’s National Weather Service releases balloons daily from about 90 stations.  As they rise through the atmosphere, the radiosondes provide information on altitude, temperature, pressure, relative humidity, and wind speed and direction. This is the information that goes into the computer models that give us our weather forecasts. The measurements from the balloons are sent into the weather models to give them as accurate a picture as possible on the current weather conditions – they also use information from satellites and ground stations. The models predict the future weather from those conditions. Forecasters often look at the radiosonde plots, which guide their decisions to issue severe weather watches. We use them to understand the different layers of wind, temperature, moisture, and clouds in the atmosphere above us.