Diurnal cycle of deep convection in super clusters embedded in the Madden-Julian Oscillation

The diurnal cycle of deep convection in the convectively active phase (CAP) and convectively suppressed phase (CSP) of the Madden-Julian Oscillation (MJO) was investigated using global infrared-equivalent blackbody temperature (TBB) data from October 2000 to April 2005. We particularly focused on super clusters (SCs) that occurred during the CAP of the MJO. To analyze the behavior of SCs and the CSP of the MJO statistically, we created composites of TBB for each case. Four regions were examined: (1) the Indian Ocean (IO), (2) the ocean area of the Maritime Continent (MCO), (3) the land area of the Maritime Continent (MCL), and (4) the western Pacific (WP). The amplitude (phase) of the diurnal cycle of deeper convection in SCs was larger than (similar to) that of the CSP of the MJO. This result is consistent with that found in a previous study. However, the diurnal cycle of deep convection in the CSP of the MJO had a clear maximum peak, especially over the MCL, but that in SCs had a broader maximum peak of deep convection, especially in oceanic regions, although the diurnal phase was similar between SCs and the CSP of the MJO. This result statistically suggests that the organization of a convective system affects the diurnal cycle of its deep convection, as described in a previous case study. We also demonstrated that the difference in the diurnal cycle of deep convection in the IO and WP regions arose from sea surface temperature differences in those regions.