The impact of the El Niño-Southern Oscillation (ENSO) on the Madden-Julian Oscillation (MJO) is studied, based on reanalysis data and output from an ensemble general circulation model (GCM) experiment. Observed monthly sea surface temperature variations over the period of 1950–99 are imposed in the deep tropical eastern/central Pacific in the course of the SST experiment. Both GCM, and reanalys...

The boreal winter Madden–Julian oscillation (MJO) remains very weak and irregular in the National Center for Atmospheric Research (NCAR) Community Atmosphere Model version 2 (CAM2) as in its direct predecessor, the Community Climate Model version 3 (CCM3). The standard version of CAM2 uses the deep convective scheme of Zhang and McFarlane, as in CCM3, with the closure dependent on convective av...

This study examines various dynamical and thermodynamical processes that characterize the Madden– Julian oscillation (MJO). Episodes of deep convection related to the MJO based on rainfall data from the Tropical Rainfall Measuring Mission (TRMM) satellite and the Global Precipitation Climatology Project (GPCP) are identified. Although broad convective envelopes are located utilizing spectrally ...

In the Indo-Pacific region, mesoscale convective systems (MCSs) occur in a pattern consistent with the eastward propagation of the large-scale convective envelope of the Madden–Julian oscillation (MJO). MCSs are major contributors to the total precipitation. Over the open ocean they tend to be merged or connected systems, while over the Maritime Continent area they tend to be separated or discr...

The authors report a significant increase in Madden–Julian oscillation (MJO)–like variability in a superparameterized version of the NCARCommunity AtmosphereModel run with high sea surface temperatures (SSTs). A series of aquaplanet simulations exhibit a tripling of intraseasonal outgoing longwave radiation variance as equatorial SST is increased from 268 to 358C. The simulated intraseasonal va...

We present a statistical analysis of the initiation and termination of boreal winter and boreal summer intraseasonal oscillations (ISOs). This study uses purely convection (infrared brightness temperature) data over a 23-year time interval from 1984–2006. The indices are constructed via the nonlinear Laplacian spectral analysis (NLSA) method and display high intermittency and non-Gaussian stati...

Herewe ask, what controls the horizontal scale of theMadden-Julian Oscillation, i.e., what controls its zonal wave number k?We present a new one-dimensional (1D) β-planemodel that successfully simulates theMJO with the same governing mechanism as the 2D shallow water model of Yang and Ingersoll (2013). Convection is parameterized as a short-duration localized mass source that is triggered when ...

The modulation of tropical cyclone activity by the Madden–Julian oscillation (MJO) is explored using an empirical genesis potential (GP) index. Composite anomalies of the genesis index associated with the different MJO phases are consistent with the composite anomalies in TC genesis frequency that occur in the same phases, indicating that the index captures the changes in the environment that a...

In Part I of this study it was shown that air–sea coupling had a positive impact on some aspects of the simulation of the Madden–Julian oscillation (MJO) by a GCM. However, errors in the basic-state climate of that GCM appeared to be preventing the MJO-related convection from propagating into the west Pacific. In this paper, the actual impact of these errors will be addressed. An integration of...

The intraseasonal fluctuations of Indian summer monsoon rainfall (ISMR) are mainly controlled by northward propagating oscillation (MISO) and eastward Madden Julian (MJO). In the current study, we examine relationship between (active break spells) ISMR with phase propagation amplitude MISO MJO. We notice that active spells generally occur during phases 2–5 (MJO 3–6), 6–8 1). association active/...