CEPEX

Central Equatorial Pacific Experiment

5 March–7 April 1993 · intensive field observations
Central equatorial Pacific; operations based in Fiji

CEPEX centred on a single intensive field campaign in 1993. Scientific analysis, collaboration, and meetings continued beyond the observing period. The project investigated how tropical convection, clouds, water vapour, and radiation interact with the warm ocean. Ship, aircraft, and satellite measurements were used to examine the ocean–atmosphere energy budget.

Research and findings

Our radiation studies showed that the shortwave cooling and longwave warming effects of convective clouds nearly cancelled near the tropopause, while clouds substantially reduced the radiant energy reaching the ocean surface. A later analysis combined ship, aircraft, and satellite measurements to quantify the much smaller longwave heating of the ocean surface by those clouds. [A15] [A21]

Related work measured the clear-sky water-vapour greenhouse effect over the equatorial Pacific. With Maria Flatau, Patricia Phoebus, and Pearn Niiler, I also used March 1993 CEPEX and TOGA COARE observations to study feedback between convection and sea-surface temperature. Coupling those temperature changes to a model altered the propagation and organisation of equatorial convection. [A16] [A17]

Related publications

1. A15

   Collins, W.D., F.P.J. Valero, P.J. Flatau, D. Lubin, H. Grassl, and P. Pilewskie. Radiative effects of convection in the tropical Pacific, Journal of Geophysical Research, 101, 14999-15012, 1996.

2. A16

   Valero, F.P.J., W.D. Collins, P. Pilewskie, A. Bucholtz, and P.J Flatau. Direct radiometric observations of the water vapor greenhouse effect over the equatorial Pacific Ocean. Science, 21 March 1997, 275, (no.5307): 1773-6.

3. A17

   Flatau, M., P.J. Flatau, P. Phoebus, and P.P. Niiler. The feedback between equatorial convection and local radiative and evaporative processes: the implication for intraseasonal oscillations. Journal of the Atmospheric Sciences, 54, 2373-2386, 1997.

4. A21

   Collins, W.D., A. Bucholtz, P.J. Flatau, D. Lubin, F.P.J. Valero, C.P. Weaver, and P. Pilewski. Determination of surface heating by convective cloud systems in the central equatorial Pacific from surface and satellite measurements. Journal of Geophysical Research-Atmospheres, V105(ND11):14807-14821, 2000.

5. B.I.26

   Flatau, M., P.J. Flatau, and P. Phoebus. Synoptic overview of CEPEX period. In Symposium on the regulation of sea surface temperatures and warming of the tropical ocean atmosphere system, pages 5-8. American Meteorological Society, AMS, January 1995.

Campaign background: NCAR: CEPEX