Investigating the Role of Cloud-Radiation Interactions in Subseasonal Tropical Disturbances

James J. Benedict, Brian Medeiros, Amy C. Clement, Jerry G. Olson

Research output: Contribution to journalArticle

Abstract

Cloud locking, a method that prescribes cloud properties for radiative tendency calculations, is traditionally used to explore climate feedbacks, but here is applied novelly to investigate cloud-radiation interaction (CRI) impacts on subseasonal tropical variability. The approach minimizes mean state differences between control (CRI active) and experimental simulations (CRI disabled) of the Community Earth System Model. Disabling CRI weakens amplitudes of the Madden-Julian oscillation (MJO) by 10–35% and equatorial Rossby waves by 10–30% yet strengthens Kelvin waves by 10–40%. MJO weakening results from suppressed radiation-convection positive feedbacks and increased gross moist stability. Kelvin waves strengthen from reduced convective inhibition and reduced radiative damping on temperature variance. The results are compared to a recently proposed theory that describes a continuum of tropical disturbances. MJO survival, when its primary maintenance mechanism (CRI) is eliminated, stresses the importance of advection and surface flux processes.

Original languageEnglish (US)
Article numbere2019GL086817
JournalGeophysical Research Letters
Volume47
Issue number9
DOIs
StatePublished - May 16 2020

Keywords

  • CESM
  • cloud locking
  • Kelvin waves
  • MJO
  • radiative-convective feedback
  • tropical intraseasonal variability

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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