Coupled Atmosphere and Ocean Boundary Layer Variability in the Suppressed Phase of the Madden-Julian Oscillation

Abstract:

The Madden-Julian Oscillation (MJO) is an important mode of tropical intraseasonal variability with numerous impacts. While recent studies continue to show the importance of atmospheric moist dynamics and convection as a driving factor in the development and propagation of MJO events, it is also known that the upper ocean mixed layer responds in concert and may itself contribute to the amplification and decay of MJO related variability. Preconditioning of the environment prior to the active phase of the MJO has been noted, but the balance of theorized mechanisms to accomplish this process remains unresolved. Further, not all developing organized convection transitions into a propagating MJO signal. Are there specific mechanisms involving air-sea interaction that are important for propagation?

This work will provide analyses of observations from satellite (AIRS/AMSU, MODIS, CERES), reanalyses, and in situ observations (buoys, Argo) to investigate atmospheric and oceanic boundary layer variability during the suppressed phase of the MJO. A particular focus of these analyses will be to characterize the systematic relationship between intraseasonal SST/upper-ocean variability, low-level stability, and observed cloud regimes. Additional emphasis will be placed on scrutinizing the interactions between the atmosphere and ocean boundary layers via surface heat flux exchanges of heat, moisture, and momentum. These relationships will be compared and contrasted between active, propagating MJO events and those organized convective events that fail to propagate.