Cirene: Air-sea interactions in the seychelles-chagos thermocline ridge region

Jérôme Vailard, J. P. Duvel, M. J. Mcphaden, P. Bouruet-Aubertot, B. Ward, E. Key, D. Bourras, R. Weller, P. Minnett, A. Weill, C. Cassou, L. Eymard, T. Fristedt, C. Basdevant, Y. Dandonneau, O. Duteil, T. Izumo, C. de Boyer Montégut, S. Masson, F. MarsacC. Menkes, S. Kennan

Research output: Contribution to journalArticle

79 Scopus citations

Abstract

The Vasco - Cirene program ex-plores how strong air - sea inter-actions promoted by the shallow thermocline and high sea surface temperature in the Seychelles - Chagos thermocline ridge results in marked variability at synoptic, intraseasonal, and interannual time scales. The Cirene oceano-graphic cruise collected oceanic, atmospheric, and air - sea flux observations in this region in Jan-uary - Februazy 2007. The contem-poraneous Vasco field experiment complemented these measure-ments with balloon deployments from the Seychelles. Cirene also contributed to the development of the Indian Ocean observing system via deployment of a moor-ing and 12 Argo profilers. Unusual conditions prevailed in the Indian Ocean during Janu-ary and February 2007, following the Indian Ocean dipole climate anomaly of late 2006. Cirene measurements show that the Seychelles - Chagos thermocline ridge had higher-than-usual heat content with subsurface anomalies up to 7°C. The ocean surface was warmer and fresher than average, and unusual eastward currents prevailed down to 800 m. These anomalous conditions had a major impact on tuna fishing in early 2007. Our dataset also sampled the genesis and maturation of Tropical Cyclone Dora, including high surface temperatures and a strong diurnal cycle before the cyclone, followed by a 1.5°C cool-ing over 10 days. Balloonborne instruments sampled the surface and boundary layer dynamics of Dora. We observed small-scale structures like dry-air layers in the atmosphere and diurnal warm layers in the near-surface ocean. The Cirene data will quantify the impact of these finescale features on the upper-ocean heat budget and atmospheric deep convection.

Original languageEnglish (US)
Pages (from-to)45-61
Number of pages17
JournalBulletin of the American Meteorological Society
Volume90
Issue number1
DOIs
StatePublished - 2009

ASJC Scopus subject areas

  • Atmospheric Science

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    Vailard, J., Duvel, J. P., Mcphaden, M. J., Bouruet-Aubertot, P., Ward, B., Key, E., Bourras, D., Weller, R., Minnett, P., Weill, A., Cassou, C., Eymard, L., Fristedt, T., Basdevant, C., Dandonneau, Y., Duteil, O., Izumo, T., de Boyer Montégut, C., Masson, S., ... Kennan, S. (2009). Cirene: Air-sea interactions in the seychelles-chagos thermocline ridge region. Bulletin of the American Meteorological Society, 90(1), 45-61. https://doi.org/10.1175/2008BAMS2499.1