Comparison of the Madden-Julian oscillation (MJO) during the TOGA COARE IOP with a 15-year climatology

During the Tropical Ocean-Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE) intensive observing period (IOP) (November 199 2 to February 1993), two pronounced Madden-Julian oscillation (MJO) events were observed and have been intensively studied. To provide a necessary cli matological basis for the case study as well as to evaluate how typical the COARE MJO cases are and to what degree conclusions made from these cases c an be generalized, we compare the MJOs that occurred during the COARE IOP w ith a 15-year climatology. In this paper, along with a description of the c haracteristics of large-scale background including flow patterns, OLR and S ST, the emphasis is placed on the intensity and propagation of the oscillat ions exhibited in organized convection and atmospheric circulation. Moreove r, the maintenance of perturbation kinetic energy (PKE) associated with 30- to 60-day variability containing the MJOs is compared as well. The COARE I OP occurred in a lingering period between the persistence and the rejuvenat ion of the warm ENSO episode of 1992-1993. The intraseasonal oscillations i n the convective activity and large-scale circulation are intensified durin g the IOP, and the maximum intensification is located in the region of cent ral Pacific. Two MJO events in the COARE IOP are typical in terms of phase propagation. The major features of the energy transformation processes, suc h as the predominant role of the generation of the perturbation available p otential energy (PAPE) by convective heating and its conversion into the PK E in the maintenance of the MJOs, found in the COARE IOP, are also displaye d in the climatology indicating the generality of the results obtained from the COARE case study.