EMEX: Equatorial Mesoscale EXperiment

Summary

The Equatorial Mesoscale Experiment (EMEX) was designed to test one main hypothesis, namely that the net diabatic heating associated with the near equatorial convective cloud systems is strongest in the upper troposphere. EMEX explored the vertical air motions and other kinematic properties of tropical mesoscale convective-cloud systems (“cloud clusters”) by direct aircraft penetration. EMEX was conducted over the tropical oceanic area north of Australia in January-February 1987, during the Southern Hemisphere (austral) summer, and was organized to coincide with two other major experimental programs being conducted in the region at the same time. The Australian Monsoon Experiment (AMEX) was a program of enhanced upper-air soundings and radar data collection in northern Australia, aimed at better documentation of those large-scale weather patterns over Australia that are associated with the ebb and flow of the Australian monsoon. AMEX provided an excellent synoptic context for the convective and mesoscale measurements obtained in EMEX. The Stratosphere-Troposphere Exchange Program (STEP) was conducted to obtain high-level aircraft measurements of trace chemicals, radiation, and other quantities above tropical convection in the region with the aim of understanding tropospheric-stratospheric interaction. These data added to those collected with the lower flying EMEX aircraft. Operation Centers for all 3 programs were located at the Australian Bureau of Meteorology Forecast Office in Darwin. The Royal Australian Air Force Base at Darwin was the primary base for EMEX and STEP aircraft, while a secondary base was located at Gove. The combination of these three independent but interlocking programs constituted a comprehensive tropical field program covering a wide range of interacting scales of phenomena under the “parent” program, the Tropical Ocean Global Atmosphere Program (TOGA).