Influence of cloud-radiation interaction on simulating tropical intraseasonal oscillation with an atmospheric general circulation model

Myong In Lee, In Sik Kang, Jong Khun Kim, Brian E. Mapes

Research output: Contribution to journalArticle

88 Scopus citations

Abstract

The influence of cloud-radiation interaction in simulating the tropical intraseasonal oscillation (ISO) is examined using an aqua planet general circulation model (GCM). Two types of simulation are conducted: one with prescribed zonal mean radiation and the other with fully interactive clouds and radiation. In contrast to the fixed radiation case, where the ISO is simulated reasonably well, the cloud-radiation interaction significantly contaminates the eastward propagation of the ISO by producing small-scale disturbances moving westward with the easterly basic winds. The small-scale disturbances are persistently excited by a strong positive feedback through interaction between cumulus-anvil clouds and radiation. The longwave interaction is shown to play a bigger role in contaminating the ISO than the shortwave interaction does. The anvil clouds reduce the longwave cooling significantly in the lower troposphere while releasing latent heating in the upper troposphere. To moderate the strong cloud-radiation feedback, the large-scale condensation scheme in the GCM is modified by reducing the autoconversion timescale, needed for cloud condensates to grow up to rain drops. In addition, upper air ice cloud contents are reduced to change the cloud albedo. These modifications make a more realistic simulation of the ISO similar to the observed.

Original languageEnglish (US)
Article number2001JD900143
Pages (from-to)14219-14233
Number of pages15
JournalJournal of Geophysical Research Atmospheres
Volume106
Issue numberD13
DOIs
StatePublished - Jul 16 2001
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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