The earth's climate has varied significantly in the past, yet climate records reveal

that in the tropics, sea surface temperatures seem to have been remarkably stable,

varying by less than a few degrees Celsius over geologic time. Today, the large

"warm pool" of the western Pacific shows similar characteristics. Its surface

temperature always exceeds 27ºC but never 31ºC. Heightened interest in this is

observation has been stimulated by questions of global climate change and the

exploration of stabilizing climate feedback processes.

Efforts to understand the observed weak sensitivity of tropical sea surface

temperatures to climate forcing has led to a number of competing ideas about the

nature of this apparent thermostat. Scientists are actively debating these ideas, as

evidenced by the recent number of papers and correspondence on the subject.

Although there remains disagreement on the processes that regulate tropical sea

surface temperature, most scientists agree that further progress in resolving these

differences requires comprehensive field observations of three-dimensional

water-vapor concentrations, solar and infrared radiative fluxes, surface fluxes of

heat and water vapor, and cloud microphysical properties.

This document describes the Central Equatorial Pacific Experiment (CEPEX)

plan to collect such observations over the central equatorial Pacific Ocean during

March 1993. When combined with the field observations being collected between

November 1992 and February 1993 in the western Pacific by the Coupled Ocean-

Atmosphere Response Experiment (COARE) and the normally available

background data from ocean buoys, national weather services, and satellites, this

special tropical Pacific data set will provide researchers with an unprecedented

observational resource for investigating how tropical sea surface temperature is


Joachim Kuettner
Chairman, CEPEX Scientific Steering Committee

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