Observations of the structures of deep convections and their environment during the active phase of an Madden-Julian oscillation event over the equatorial western Pacific

Abstract

The structures of deep convections and their environment were examined during the latter half of the active phase of the Madden-Julian oscillation (MJO), using fine temporal resolution of research vessel observation data. During the intensive observation period, the MJO associated with deep convections passed through the observation area. A strong westerly wind also appeared during the active phase of the MJO. Vertical structures associated with convective activity were detected using lag correlations of atmospheric parameters. Convective activity included deep convections, with a nocturnal maximum and another peak 12 to 18 hours earlier. Active convections associated with the first peak developed in the afternoon and decayed within a few hours. Those active convections transported water vapor to the lower to middle troposphere, making the environment favorable for the more intensive deep convections that developed during the night. Westerly winds were intensified in the lower layers during the deep convections. © 2006, Meteorological Society of Japan.