Dropsonde launch (top), ARA engineer Brian Zadler with an ultralight dropsonde (bottom).
On a calm March morning, ESRL researchers and engineers from Applied Research Associates, Inc. watched as their newly-developed ultralight dropsondes drifted 950 feet down from the NOAA BAO tower in Erie, Colo. at about 10 m per second. “The drops were very successful,” said Russ Chadwick of ESRL’s Global Systems Division. “We experienced near-laboratory conditions.” The palm-sized, bullet-shaped capsules with long tyvex tails carried wafer-thin circuit boards comprising a microprocessor, GPS receiver, battery, and transducers that measure temperature, pressure, relative humidity, and wind speed/direction. The ultralight dropsondes weigh less than half as much as existing dropsondes, which is crucial, because the intention of the collaborative effort is to develop an instrument that can be deployed from ultralight Unmanned Aircraft Systems (UAS). Eventually, solar-powered UAS, capable of traveling for weeks over remote areas of the oceans, could carry dozens of ultralight dropsondes, enabling low-cost collection of key environmental observations.