Launching Weather Balloons in 45-mile-per-hour Winds

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Brookhaven Lab atmospheric scientist Ernie Lewis with a mini "weather" balloon aboard the Horizon

 

This guest post was written by Ernie Lewis, an atmospheric scientist at Brookhaven Lab, who is leading a year-long climate study aboard two Horizon Lines cargo ships, the Spirit and Reliance. He recently returned from a preliminary "cruise" from L.A. to Hawaii and back aimed at assessing conditions for deploying instruments aboard the ships during the actual study, dubbed MAGIC, which will run from October 2012 through September 2013.

Hawaii was wonderful, even though I only had a short time in Waikiki Beach (I'm getting no sympathy from my friends at work on this point, so I'm trying a wider audience). Our team of scientists left Los Angeles on MAGIC Leg00a on Saturday, February 11, at 5:30 a.m., along with nearly 1,000 cargo containers aboard the Horizon Spirit. We spent the previous two days installing a meteorological (met) system on the mast and a navigation system to characterize ship motion to aid in determining how to keep one of the radars and other instruments pointed vertically when the ship rolls. Both the met system and the navigation system worked very well for the entire cruise. We arrived in Honolulu on Wednesday, February 15, at 9:30 p.m., after a mostly cloudy and cool trip. Fortunately the seas weren't too rough and there was no seasickness (hurray!).

Thursday in Hawaii we checked the instruments, met with personnel at the Horizon office in Honolulu, picked up some supplies, met colleagues for lunch, and did a cursory check of email to see if there were any emergencies. We had just enough time after our errands to buy a few Hawaiian shirts and have one Mai Tai at Waikiki Beach before turning in the rental car and returning to the Spirit. We departed at 11 p.m. on MAGIC Leg00b, and arrived back in Los Angeles on Thursday, February 23, at 7 a.m.

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Preparing to launch a real weather balloon with vegetable ballast

The trip back was much windier! The ship was traveling at 15 knots and we had headwinds of 25 knots most of the way home. That's a relative wind speed of more than 45 miles per hour! One of the goals of the trip was to investigate the feasibility of weather balloon launches from different locations around the ship. Filling balloons on deck in those conditions is, needless to say, quite challenging, and there were strong downdrafts around the ship, which added another challenge.

I am proud to report that during the cruise we successfully launched five potatoes, two turnips, one avocado, four sweet potatoes, one rutabaga, and three squash. These vegetables served as stand-ins for the meteorological sensing packages we'll launch during the real study. They're about the same weight, biodegradable, and don't cost nearly as much as the actual instruments. We sent only one squash into the ocean, had one explode in hand, and popped only two balloons.

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A successful launch

Though these launches were a source of amusement for the Spirit crew (and for us), they were nevertheless important, as launches will be made four times daily during the MAGIC deployment. Nearly 1,000 sites around the world routinely launch two weather balloons daily to collect data used for weather forecasts. The balloons are filled with helium to a diameter of about one meter, with "sondes" containing sensors attached below the balloons. From measurements of temperature, pressure, location (via GPS), and relative humidity, a detailed profile of atmospheric structure (i.e., temperature and relative humidity as a function of height) can be obtained. During the actual study, these measurements will form part of the data set that helps us construct a long-term scientific picture of clouds over the ocean with the goal of improving how these climate drivers are incorporated into future climate models.

For more about the study and future updates, see the MAGIC web site.

Posted by Karen McNulty Walsh, Brookhaven Lab Media & Communications Office

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