ABSTRACT
Organization of convection within the Madden-Julian
oscillation
Harry H. Hendon
Program in Atmospheric and Oceanic Sciences and Cooperative
Institute for Research in Environmental Sciences, University
of Colorado, Boulder
Brant
Liebmann
Cooperative Institute fir Research in Environmental Sciences,
University of Colorado, Boulder
Abstract
Convection associated with the Madden-Julian oscillation
(MJO) is organized over a broad range of time and space
scales within a large-scale envelope of activity. The
large-scale envelpoe of convection is characterized as an
eastward propagating disturbance, predominantly of zonal
wavenumber 2, which os confined over the warmest waters of
the Indian and western Pacific oceans. Large-scale
convection is shifted toward the disturbance's temperature
anomaly. which appears to result from frictional effects in
the boundary layer. Synoptic and mesoscale convection
activity is enhanced within the wet phase of the large-scale
envelope. The increase at synoptic scales occurs uniformly
over all scales, but little difference in the character of
the variability is observed between dry and wet phases. The
enhanced mesoscale activity within the wet phase exhibits a
marked tenency to be organized into westward propagating
clusters with periods near 2 days and half wavelengths of
about 1000km. The role of these modes for the evolution of
the MJO is discussed.