In its default configuration, the Hadley Centre climate model (GA2.0) simulates roughly one-half the observed level of Madden–Julian oscillation activity, with MJO events often lasting fewer than 7 days. We use initialized, climate-resolution hindcasts to examine the sensitivity of the GA2.0 MJO to a range of changes in subgrid parametrizations and model configurations. All 22 changes are teste...

[1] A number of competing theories to explain the initiation mechanism, longevity and propagation characteristics of the Madden-Julian Oscillation (MJO) have been developed from observational analysis of the tropical climate and minimal dynamical models. Using the isotopic composition of atmospheric moisture from paired satellite retrievals of H2O and HDO from the boundary layer and mid troposp...

The Madden–Julian Oscillation (MJO) is the dominant component of intraseasonal (30–90 days) variability in the tropical atmosphere. Here, traveling wave solutions are presented for the MJO skeleton model of Majda and Stechmann. The model is a system of nonlinear partial differential equations that describe the evolution of the tropical atmosphere on planetary (10,000– 40,000 km) spatial scales....

[1] Both El Niño-Southern Oscillation (ENSO) and the Madden-Julian Oscillation (MJO) have previously been documented to impact Atlantic basin tropical cyclone (TC) activity through alterations in large-scale fields such as vertical wind shear, mid-level moisture, sea level pressure and sea surface temperature. Atlantic TC activity has been shown to be enhanced when La Niña conditions are presen...

[1] The Madden-Julian Oscillation (MJO) is the dominant component of the intraseasonal (30–90 days) variability in the tropical atmosphere. It consists of large-scale coupled patterns in atmospheric circulation and deep convection, with coherent signals in many other variables, all propagating eastward slowly ( 5 m s ) through the portion of the Indian and Pacific oceans where the sea surface i...

The eastward propagating Madden-Julian Oscillation (MJO) typically exhibits complex behavior during its passage over the Maritime Continent, sometimes slowly propagating eastward and other times stalling and even terminating there with large amounts of rainfall. This is a huge challenge for present-day numerical models to simulate. One possible reason is the inadequate treatment of the diurnal ...

This study investigates the October and November MJO events observed during the Cooperative Indian Ocean Experiment on Intraseasonal Variability in the Year 2011 (CINDY)/Dynamics of the MJO (DYNAMO) field campaign through cloud-permitting numerical simulations. The simulations are compared to multiple observational datasets. The control simulation at 9-km horizontal grid spacing captures the sl...

A minimal, nonlinear oscillator model is analyzed for the Madden–Julian oscillation (MJO) ‘‘skeleton’’ (i.e., its fundamental features on intraseasonal/planetary scales), which includes the following: (i) a slow eastward phase speed of roughly 5 m s, (ii) a peculiar dispersion relation with dv/dk ’ 0, and (iii) a horizontal quadrupole vortex structure. Originally proposed in recent work by the ...

This study investigates the convective population and environmental conditions during three MJO events over the central Indian Ocean in late 2011 using measurements collected from the Research Vessel (R/V) Roger Revelle deployed in Dynamics of the MJO (DYNAMO). Radar-based rainfall estimates from the Revelle C-band radar are first placed in the context of larger-scale Tropical Rainfall Measurin...

Convectively coupled Kelvin waves (CCKWs) are atmospheric weather systems that propagate eastward along the equatorial wave guide with phase speeds between 11 and 14ms . They are an important constituent of the convective envelope of the Madden-Julian oscillation (MJO), for which ocean-atmosphere interactions play a vital role. Hence, ocean-atmosphere interactions within CCKWs may be important ...