Organization of Oceanic Convection during the Onset of the 1998 East Asian Summer Monsoon

  • Johnson R
  • Aves S
  • Ciesielski P
 et al. 
  • 27

    Readers

    Mendeley users who have this article in their library.
  • 43

    Citations

    Citations of this article.

Abstract

The organizational modes of convection over the northern South China Sea (SCS) during the onset of the summer monsoon are documented using radar and sounding data from the May-June 1998 South China Sea Monsoon Experiment (SCSMEX). The onset occurred in mid-May with a rapid increase in deep convection over a 10-day period, accompanied by a major shift in the circulation over the east Asian region. Analysis of Bureau of Meteorology Research Centre (BMRC) radar data from Dongsha Island reveals a wide range of organizational modes of convection over the northern SCS. Proximity sounding data indicate that lower- and middle-level vertical wind shears exerted a dominant control over the orientation of convective lines within mesoscale convective systems in this region, as has been found in the Australian monsoon region and the equatorial western Pacific. The results are consistent with the conceptual model of LeMone et al. based on the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE), except two new organizational modes have been identified shear-parallel bands for strong low-level shear and weak midlevel shear when there is weak instability and the air is dry aloft, and shear-parallel bands for strong shears in both layers when the shear vectors are in the same direction. Midlatitude influences, namely, the passage of troughs over southern China, Iikely contributed to these two additional modes. The stratiform rain fraction from the convective systems during the monsoon onset period was relatively small (260/0) compared to the estimated average of about 40% for the entire Tropics. This small fraction is attributed to the weak instability during the onset period and relatively dry air in the upper troposphere.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Authors

  • Richard H. Johnson

  • Steven L. Aves

  • Paul E. Ciesielski

  • Thomas D. Keenan

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free