The GATE Dropwindsonde Program

This article on the GATE (GARP Atlantic Tropical Experiment) 1974 program for using dropwindsondes in field operations (for the first time) describes the equipment and system for measuring temperature, humidity, pressure, and wind from sondes dropped from aircraft flying at about 10 km at a speed of 220 m/sec with soundings spaced about 2.2 degrees lat. (244 km) apart. When specific convective disturbances were being studied, sondes were released more often (closer spacing). A typical mission (Aug. 10, 1974) of GATE is described in detail and illustrated by means of flight track charts (with actual observed winds at 100-mb layers from 950 to 450 mb). Typical soundings for three locations in a disturbance near the ITCZ on Sept 7, 1974, are also discussed and illustrated, and a cross section of winds and clouds (trade wind cumulus, higher cumulus, nimbus, alto cumulus, and alto stratus) in a trade-wind disturbance west of Dakar on Aug. 8, 1974, is presented and commented upon with respect to circulation dynamics in the Eastern Atlantic. Future applications of dropwindsondes are outlined for a wide range of data acquisition during reconnaissance of synoptic mesoscale convective systems over oceans.