Dropsonde

A dropsonde is an expendable weather reconnaissance device created by the National Center for Atmospheric Research (NCAR), designed to be dropped from an aircraft at altitude to more accurately measure (and therefore track) tropical storm conditions as the device falls to the surface. The sonde contains a GPS receiver, along with pressure, temperature, and humidity (PTH) sensors to capture atmospheric profiles and thermodynamic data. It typically relays these data to a computer in the aircraft by radio transmission.

The device's descent is slowed and stabilized by a small square-cone parachute, allowing for multiple readings to be taken before it reaches the ocean surface. The sonde is a lightweight system designed to be operated by one person and is launched through a chute installed in the measuring aircraft, with immediate deployment of the parachute to reduce or eliminate any pendulum effect, and typically drops from three to five minutes. The sonde has a casing of stiff cardboard. During a typical hurricane season, the 53d Weather Reconnaissance Squadron Hurricane Hunters deploys 1000 to 1500 sondes on training and storm missions.

Dropsondes are commonly used by Hurricane Hunters to obtain meteorological data on hurricanes, and these data are then fed into supercomputers for numerical weather prediction, enabling forecasters to track and predict what will happen to the hurricane. To obtain the data, an aircraft, either operated by NOAA or the U.S. Air Force flies into the hurricane. The dropsonde is released when the plane reaches the eye (center) of the hurricane, normally at around 10,000 feet (approx. 3,000 meters). The dropsonde sends back coded data, which includes:

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