Aerological Measurements

Many aerological measurements rely on compact radiosondes, which are carried into the atmosphere using rubber balloons. Radiosondes measure essential atmospheric state parameters: pressure, temperature, humidity, and winds. Although sensor technology is similar to the sensors used in ground-based measurements, sensors used on radiosondes must be able to measure a much wider range of conditions and to operate in difficult environments. Many different technologies for radiosonde sensors exist. Here, common sensor technology in modern radiosondes is described. Radiosonde pressure measurements either use specialized small solid-state sensors or rely on pressure derived from global navigational satellite system (GNSSGlobal Navigation Satellite System (GNSS)) height measurements. Temperature measurements either use small thermistors or wire resistance thermometers. Coatings to minimize solar radiative heating and accumulation of water on the sensor reduce measurement artifacts. Modern humidity sensors are almost exclusively based on thin film polymer sensors, which are optimized for atmospheric observations under a wider range of conditions and may have heaters implemented to reduce icing problems. Wind measurements are based on GNSS signals received onboard the radiosondes. Radiosonde technology is also used on dropsondes, which are deployed from aircraft for targeted observations of severe weather and hurricanes, as well as on tethered systems. Data sharing through international systems is an important component in the distribution and use of global radiosonde data. Technical specifications, quality control, and maintenance considerations, as well as an outlook on applications and future developments are presented.