Over the global tropics, the Madden-Julian Oscillation (Madden and Julian 1994, MJO) explains a significant amount of the variability in circulation and convection on intraseasonal time scales. However, significant variation exists in the spatial extent and seasonal occurrence of the MJO. While the upper-level divergent flow associated with MJO is often traced around the globe, the low-level wi...

The Madden–Julian oscillation (MJO) influences tropical cyclone formation around the globe. Convectively coupled Kelvin waves are often embedded within the MJO, but their role in tropical cyclogenesis remains uncertain. This case study identifies the influences of the MJO and a series of Kelvin waves on the formation of two tropical cyclones. Typhoons Rammasun and Chataan developed in the weste...

The Madden–Julian oscillation (MJO) is the dominant mode of variability in the tropical atmosphere on intraseasonal time scales and planetary spatial scales. Despite the primary importance of the MJO and the decades of research progress since its original discovery, a generally accepted theory for its essential mechanisms has remained elusive. In recent work by two of the authors, a minimal dyn...

13 The Madden Julian Oscillation (MJO) was shown to a ect both present-day Sudden Strato14 spheric Warming (SSW) events in the Arctic, and their future frequency under global 15 warming scenarios, with implications to the Arctic Oscillation and mid-latitude extreme 16 weather. This work uses a dry dynamic core model to understand the dependence of SSW 17 frequency on the amplitude and longitudi...

[1] The vertical distribution of radiative heating affects the moist static energy budget and potentially the maintenance and propagation of the Madden‐Julian Oscillation (MJO). This paper usesCloudSat data to examine the radiative heating climatology in the tropics and the vertical structure of its modulation by the MJO and convectively coupled Kelvin Waves (KWs). Composites of active regions ...

It is well known that the envelope of the Madden–Julian oscillation (MJO) consists of smaller-scale convective systems, including mesoscale convective systems (MCS), tropical cyclones, and synoptic-scale waves called ‘‘convectively coupled equatorial waves’’ (CCW). In fact, recent results suggest that the fundamental mechanisms of the MJO involve interactions between the synoptic-scale CCW and ...

We propose simplified metrics to evaluate the fidelity with which the Madden–Julian oscillation (MJO) is simulated in climate models. These metrics are based on lag correlation analysis of principal component time series (PCs). The PCs are obtained by projecting simulated 20–100 day bandpass filtered daily outgoing longwave radiation onto the two leading empirical orthogonal functions of observ...

Changes in the Madden-Julian Oscillation (MJO) with increasing CO2 concentrations are examined using the Goddard Institute for Space Studies Global Climate Model (GCM). Four simulations performed with fixed CO2 concentrations of 0.5, 1, 2, and 4 times preindustrial levels using the GCM coupled with a mixed layer ocean model are analyzed in terms of the basic state, rainfall, moisture and zonal ...

The land-sea surface temperature contrast on the western coast of Sumatra Island was examined using observation data obtained from the pre-Years of the Maritime Continent (YMC) field campaign from November to December 2015. Surface observations showed that, on most days, strong daytime solar radiation caused a pronounced diurnal cycle in surface air temperatures on the island, even during the l...

In this paper, we report the triggering effect of extratropical perturbation on the onset of an atypical Madden-Julian Oscillation (MJO) and onset of the 2015-16 El Niño in March 2015. The MJO exhibited several unique characteristics: the effect of extratropical forcing, atypical genesis location and timing in the equatorial western Pacific, and the extremity of amplitudes in many aspects. The ...