The Madden-Julian oscillation observed during the TOGA COARE IOP: Global view

During the TOGA COARE Intensive Observing Period (November 1992-Februnry 19 93), two pronounced Madden-Julian oscillation (MJO) events associated with super cloud clusters and westerly wind bursts were observed. This paper pre sents a global view of the MJOs including the origin of the super clusters in the Indian Ocean, their migration into the Maritime Continent and the TO GA COARE large-scale soundings array (LSA) in the western equatorial Pacifi c, and their rapid decay over cold water of the eastern Pacific. The struct ure and evolution of the MJO are examined with emphasis on the coupling bet ween large-scale motion and convection. Because of differences in propagati on speeds, the positions of maximum zonal wind perturbations relative to de ep convection undergo systematic changes during the travel of the MJO. Howe ver, the centers of deep convection always coincide with those of large-sca le ascent. The super cloud cluster accompanies a wide area of warm air in t he upper troposphere. Over the warm pool region the perturbation kinetic en ergy of the motion in the 30-60-day period range is maintained by the conve rsion of perturbation available potential energy generated by convective he ating. Over the central-eastern Pacific, there is strong horizontal converg ence of wale energy Bur entering the equatorial upper-tropospheric westerly duct from the extratropical latitudes, suggesting interactions of the MJO with midlatitude disturbances.