Autonomous Aerosondes for Economical Atmospheric Soundings Anywhere on the Globe

Considerable interest in the use of autonomous aircraft for atmospheric measurements in remote and hazardous areas worldwide has arisen over recent years. Their application in tropical cyclone reconnaissance is under study by the World Meteorological Organization and the International Council for Scientific Unions under the United Nations International Decade for Natural Disaster Reduction. More diverse experiments, particularly for stratospheric operations, are being planned by agencies in the United States. The aerosonde can provide an economical and flexible element in these international initiatives. The concept is for a small aircraft (weighing less than 20 kg) with on-board meteorological sensors to provide radiosonde-quality observations at any location on the globe. Individual missions could span several thousand kilometers and several days' duration, using the Global Positioning System for autonomous navigation, and satellite relay for data return and flight-plan updates. With a supercharged engine, the aerosonde could make soundings from sea level to 100 hPa and back in a cycle of about 4 h. Aerosondes flying such profiles in routine wide-scale use are expected to achieve a per-sounding cost competitive with that of balloon-borne radiosondes, but with much greater flexibility of operation.