GATE: GARP Atlantic Tropical Experiment

Summary

The Global Atmospheric Research Program's (GARP) Atlantic Tropical Experiment took place in the summer of 1974. Because of its enormous size (72 nations were involved) and scope, the GATE experiment was divided into a Central Program, which ensured that the central objective was met, and five sub-programs, whose primary objectives supported the central objective.

The central scientific objective of GATE was to look at the effects of smaller-scale tropical weather systems, such as cloud clusters, on larger scale motions (scale interaction), and to improve numerical modeling and prediction methods. This was done through providing datasets suitable for numerical-modeling testing and development of parameterization schemes for use in numerical models. GATE data have been used for evaluation of models varying from large-eddy simulations to numerical weather prediction models, and for testing and evaluation of parameterization schemes for the boundary layer and mesoscale convective systems.

The five sub-programs and their primary objectives were: (1) Synoptic-Scale Subprogram, to describe the synoptic scale phenomena from West Africa to the western Atlantic Ocean, and from the troposphere through the lower stratosphere. (2) Convection Subprogram, to document mesoscale convective systems and their interaction with their environment and other scales. (3) Boundary-Layer Subprogram, to document the surface fluxes, atmospheric boundary layer structure and fluxes, and boundary-layer interaction with clouds, for suppressed (fair-weather) to the highly disturbed conditions associated with precipitating convection. (4) Radiation subprogram, to document the radiative heating profiles and on the net radiation and its components at the surface, for the range of convective conditions, from suppressed to highly disturbed (5) The Oceanographic Subprogram, to study ocean-atmosphere interaction at various scales, including the structure of the upper ocean, and the coupling between ocean currents and surface winds.