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...

[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...

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...

California receives most of the annual precipitation during the boreal winter season. Additionally, large spatial and temporal variations in the total rainfall amounts are observed. This study investigates the occurrence of extreme precipitation events in California and the modulation by the Madden–Julian oscillation (MJO). Three questions are investigated. 1) Are extreme precipitation events i...

We investigate in this paper the dominant intraseasonal signals in both convection and circulation data using the nonlinear Laplacian spectral analysis (NLSA) method. Three Madden-Julian oscillation (MJO) indices are constructed based on temporal modes extracted from pure cloudiness, lowerand upper-level zonal wind anomalies. All three indices reveal strong intermittency and capture well – thro...

This work studies the spatiotemporal structure and regime predictability of large-scale intraseasonal oscillations (ISOs) of tropical convection in satellite observations of infrared brightness temperature (Tb). Using nonlinear Laplacian spectral analysis (NLSA), a data analysis technique designed to extract intrinsic timescales of dynamical systems, the Tb field over the tropical belt 15◦S–15◦...

Dynamical understanding of the Madden-Julian Oscillation (MJO) has been elusive, and predictive capabilities therefore limited. New measurements of the ocean's response to the intense surface winds and cooling by two successive MJO pulses, separated by several weeks, show persistent ocean currents and subsurface mixing after pulse passage, thereby reducing ocean heat energy available for later ...

The behavior of convection and the Madden–Julian oscillation (MJO) is compared in two simulations from the same global climate model but with two very different treatments of convection: one has a conventional parameterization of moist processes and the other replaces the parameterization with a two-dimensional cloud-resolving model, the so-called superparameterization. The different behavior o...

We investigate how the Madden-Julian Oscillation (MJO), dominant mode of tropical subseasonal variability, modulates lifecycle cool-season North Pacific atmospheric rivers (ARs). When enhanced (suppressed) convection center is located over Indian Ocean (western Pacific), more AR events originate eastern Asia and with fewer subtropical northern Pacific. western (Indian Ocean), opposite changes o...