GARP Atlantic Tropical Experiment

GARP Atlantic Tropical Experiment
Name	GARP Atlantic Tropical Experiment
Abbreviation	GATE
Period	1974
Location	Tropical Atlantic Ocean, West Africa
Field	Atmospheric science, Meteorology, Oceanography
Lead organizers	World Meteorological Organization, National Science Foundation, National Oceanic and Atmospheric Administration
Participants	International teams from United States, United Kingdom, Nigeria, Brazil, France, Soviet Union

GARP Atlantic Tropical Experiment The GARP Atlantic Tropical Experiment (GATE) was a large-scale international field program in 1974 that investigated tropical meteorology, convective systems, and ocean–atmosphere interactions across the eastern tropical Atlantic. The project brought together researchers and platforms from agencies and institutions to study mesoscale and synoptic processes associated with African easterly waves, tropical cyclogenesis, and convective organization. GATE generated extensive observational datasets that influenced subsequent programs in atmospheric sciences and tropical meteorology.

Background and objectives

GATE was conceived within the context of the Global Atmospheric Research Program and designed through coordination among the World Meteorological Organization, the National Oceanic and Atmospheric Administration, and the National Science Foundation, with input from the Royal Society and the International Council of Scientific Unions. Motivated by limitations in understanding of tropical convection demonstrated in studies by the National Center for Atmospheric Research, the European Centre for Medium-Range Weather Forecasts, and the United States Air Force, objectives emphasized synoptic-scale forcing, mesoscale convective systems, and ocean–atmosphere coupling. Key goals included improving parameterizations used by the Naval Research Laboratory and operational centers such as the Met Office and validating models developed at the Lamont–Doherty Earth Observatory and the Scripps Institution of Oceanography.

Experimental design and methodology

The campaign architecture combined ship-based, aircraft, radiosonde, and satellite observations, coordinated through operational control by agencies including the NOAA Atlantic Oceanographic and Meteorological Laboratory and the United Kingdom Meteorological Office. Field design featured a 2000 km observation array spanning from the Gulf of Guinea to the Caribbean, with staggered intensive observation periods managed by teams from the Max Planck Institute for Meteorology, the Institut Français de Recherche pour l'Exploitation de la Mer, and the Geophysical Fluid Dynamics Laboratory. Methodological approaches integrated synoptic analyses pursued by the European Space Research Organisation with diagnostic studies from the National Aeronautics and Space Administration and process studies used by the Jet Propulsion Laboratory and the Woods Hole Oceanographic Institution.

Observations and instrumentation

Instrumentation included research aircraft such as platforms operated by the United States Navy and the Royal Air Force, instrumented ships from the United States Coast Guard and the Federal Republic of Germany, and extensive radiosonde networks run by national services like the Nigerian Meteorological Agency and the Brazilian National Institute for Space Research. Satellite data from the Applications Technology Satellite series and the European Space Agency missions were assimilated alongside conventional observations from the National Meteorological Center. In situ sensors comprised Doppler radar installations similar to those used by the Air Force Cambridge Research Laboratories, airborne radars developed at the Massachusetts Institute of Technology, flux buoys provided by the Scripps Institution of Oceanography, and oceanographic instrumentation from the National Oceanographic Data Center.

Major findings and scientific impact

GATE clarified the role of African easterly waves originating near the Sahara and propagating across regions monitored by the Gulf of Guinea in initiating organized convection and tropical disturbances, informing theories promoted by researchers at the University of Miami and the Colorado State University. Results influenced convective parameterizations implemented at the European Centre for Medium-Range Weather Forecasts and operational forecasting at the National Hurricane Center and the Joint Typhoon Warning Center. The experiment produced seminal datasets used by the Pennsylvania State University and the University of Reading for studies on mesoscale convective systems, and underpinned model development at the Princeton University Geophysical Fluid Dynamics Laboratory and the National Center for Atmospheric Research, thereby affecting climate modeling at institutions like the Hadley Centre.

Collaboration and participating institutions

GATE represented collaboration among national meteorological services including the Nigeria Meteorological Agency, the Brazilian National Institute for Space Research, the Soviet Hydrometeorological Service, and the French National Centre for Scientific Research, with major contributions from academic and government laboratories such as the National Center for Atmospheric Research, the Scripps Institution of Oceanography, the Lamont–Doherty Earth Observatory, and the Jet Propulsion Laboratory. International organizations including the World Meteorological Organization and the Intergovernmental Oceanographic Commission played coordinating roles, while logistical support involved the United States Navy, the Royal Navy, and commercial shipping companies contracted through agencies like the National Science Foundation.

Legacy and subsequent research initiatives

GATE established observational standards and datasets that directly informed later programs such as the Tropical Ocean Global Atmosphere program, the TOGA COARE field experiment, the Atlantic Tradewind Experiment, and the African Monsoon Multidisciplinary Analysis. The experiment’s archives have been extensively reanalyzed by teams at the University Corporation for Atmospheric Research, the European Centre for Medium-Range Weather Forecasts, and the National Center for Atmospheric Research, and fed into subsequent campaigns like NAME (North American Monsoon Experiment) and the Dynamics of the Madden–Julian Oscillation studies. GATE’s influence persists in operational forecasting at the National Hurricane Center and in climate research at the Hadley Centre and the Max Planck Institute for Meteorology.

Category:Atmospheric experiments Category:1974 in science