The observed convective adjustment time (CAT) associated with Madden–Julian Oscillation (MJO) precipitation is found to vary significantly in space. Here, we investigate the effect of different spatial distributions of CAT on MJO precipitation based on the frictional coupled dynamics moisture (FCDM) model. The results show that a large value of CAT tends to decrease the frequency and growth rat...

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/...

A procedure is presented to estimate the role of atmospheric stochastic forcing (SF) in El Niño–Southern Oscillation (ENSO) simulated by a coupled ocean–atmosphere general circulation model (CGCM), in direct comparison to observations represented by a global reanalysis product. SF is extracted from the CGCM and reanalysis as surface wind anomalies linearly independent of the seasurface temperat...

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...

Summertime cloud-to-ground lightning strikes are responsible for the majority of wildfire ignitions across vast sections of the seasonally dry western United States. In this study, a strong connection between active phases of the Madden–Julian oscillation (MJO) and regional summertime lightning activity was found across the interior western United States. This intraseasonal mode of lightning ac...

This paper presents the results of forecasting the Madden-Julian oscillation (MJO) and boreal summer intraseasonal oscillation (BSISO) through the use of satellite-obtained global brightness temperature data with a recently developed nonparametric empirical method. This new method, referred to as kernel analog forecasting, adopts specific indices extracted using the technique of nonlinear Lapla...

[1] As the Madden-Julian oscillation (MJO) moves eastward from the Indian to the Pacific ocean, it typically accelerates, becomes less strongly coupled to convection, and becomes more similar to a dry Kelvin wave. This transition is analyzed using observations of outgoing longwave radiation and ERA Interim reanalyses of surface pressure and 850 hPa zonal wind. Two individual example events as w...

The long-term goal of this project is to understand the role of the atmosphere-ocean interaction processes in the initiation, maintenance and propagation of Madden Julian Oscillation (MJO). Better grasp of the atmosphere/ocean feedbacks in the Tropics will allow formulating more accurate parameterizations of the air-sea interface in the forecasting models. It will contribute to improved predict...

We investigate here both the dominant modes of variability and the large-scale regimes associated to tropical convection that can be recovered from infrared brightness temperature data using data mining and machine learning approaches. A hierarchy of spatiotemporal patterns at different timescales is extracted using a nonlinear dimension reduction method, namely Nonlinear Laplacian Spectral Ana...

The “Vertical structure and physical processes of the Madden-Julian oscillation (MJO)” project comprises three experiments, designed to evaluate comprehensively the heating, moistening, and momentum associated with tropical convection in general circulation models (GCMs). We consider here only those GCMs that performed all experiments. Some models display relatively higher or lower MJO fidelity...