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Klaus Weickmann and Edward Berry

) atmospheric dynamics and “external” boundary forcing (e.g., sea surface temperature) influence the evolution of the coupled ocean–atmosphere system. Understanding the time and space scales of the band, and its interaction with adjacent time bands, is a scientific challenge with applications to global weather–climate modeling and extended-range prediction. The tropical Madden–Julian oscillation (MJO; Madden and Julian 1972 ) and the extratropical teleconnection patterns ( Wallace and Gutzler 1981 ) are

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Bin Guan, Duane E. Waliser, Noah P. Molotch, Eric J. Fetzer, and Paul J. Neiman

status may be possible if storm activities are considerably mediated by the slowly varying large-scale atmospheric/oceanic conditions, such as those related to the Madden–Julian oscillation (MJO). It is generally understood that the tropical/subtropical Pacific Ocean has far reaching impacts on the U.S. weather and climate. A number of studies have linked the MJO to changes in the North Pacific circulation patterns and West Coast precipitation ( Higgins and Mo 1997 ; Mo and Higgins 1998 ; Bond and

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Joseph Egger and Klaus Weickmann

1. Introduction It is generally accepted that the Madden–Julian oscillation (MJO; Madden and Julian 1971 ; see Zhang 2005 for a recent review) is responsible for the spectral peak of global axial angular momentum (AAM) observed near the 50-day period ( Rosen and Salstein 1983 ). Weickmann et al. (1992) described in detail the angular momentum cycle that accompanies the MJO (see also Langley et al. 1981 ; Anderson and Rosen 1983 ). The global AAM anomalies were found to be positive

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Xianan Jiang, Duane E. Waliser, Matthew C. Wheeler, Charles Jones, Myong-In Lee, and Siegfried D. Schubert

1. Introduction Since its discovery in the early 1970s, the significant role of the Madden–Julian oscillation (MJO; Madden and Julian 1994 ) as a component of the tropical variability has been widely recognized. The MJO activities have been found to be intimately associated with onset and active/break conditions of the Asian ( Yasunari 1979 ; Lau and Chan 1986 ; Goswami 2005 ; Waliser 2006 ) and Australian ( Hendon and Liebmann 1990 ; Wheeler and McBride 2005 ) monsoons. The MJO

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Daniel B. Thompson and Paul E. Roundy

1. Introduction Tropical convection affects circulation patterns in the midlatitudes by redistributing mass, which results in large-scale overturning circulations and Rossby wave trains that extend eastward and poleward from the source convection ( Sardeshmukh and Hoskins 1988 ). The Madden–Julian oscillation (MJO; Madden and Julian 1994 ; Zhang 2005 ), a planetary-scale, eastward-propagating pattern of winds and deep convection near the equator, has been correlated with anomalies in the

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Charles Jones, Jon Gottschalck, Leila M. V. Carvalho, and Wayne Higgins

extreme precipitation. Third, previous studies have demonstrated that the Madden–Julian oscillation (MJO; Madden and Julian 1994 ; Lau and Waliser 2005 ; Zhang 2005 ) influences the occurrences of extreme precipitation in the tropics and extratropics of both hemispheres ( Mo and Higgins 1998a ; Higgins et al. 2000a ; Jones 2000 ; Bond and Vecchi 2003 ; Carvalho et al. 2004 ; Jones et al. 2004a ; Liebmann et al. 2004 ; Barlow et al. 2005 ; Donald et al. 2006 ; Jeong et al. 2008 ). Since the

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John T. Abatzoglou and Timothy J. Brown

.g., associated with initial conditions) and climate forecasts (e.g., associated with boundary conditions). The Madden–Julian oscillation (MJO), the dominant mode of intraseasonal (20–90 days) variability in the tropics, represents an important, yet to-date relatively unexploited source of applied intraseasonal predictability. The MJO is characterized by an eastward-propagating Kelvin–Rossby wave in the tropics dominated by large-scale regions of enhanced and suppressed deep convection and precipitation

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Samuel N. Stechmann and Andrew J. Majda

1. Introduction To identify the Madden–Julian oscillation (MJO), a large number of methods have been used. In their pioneering studies, Madden and Julian (1971 , 1972) detected the oscillation in zonal wind, pressure, and temperature data. Subsequently, many MJO indices have been defined using different fields of interest: winds only (e.g., Chen and Del Genio 2009 ), cloudiness or precipitation only (e.g., Kiladis et al. 2005 ), or combinations of winds and cloudiness (e.g., Wheeler and

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Bradford S. Barrett and Lance M. Leslie

cyclogenesis tends to cluster in time, with a two- to three-week period of multiple instances of TCs, followed by a two- to three-week period of few to no occurrences of cyclogenesis. This temporal periodicity suggests a connection to an intraseasonal mode of variability, such as the Madden–Julian oscillation (MJO; Madden and Julian 1971 , 1972 ). It is in this window that accurate guidance, particularly in forecasting cyclogenesis, would prove highly useful ( Hall et al. 2001 ; Bessafi and Wheeler 2006

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Michael J. Ventrice, Chris D. Thorncroft, and Paul E. Roundy

1. Introduction The Madden–Julian oscillation (MJO) is the leading mode of intraseasonal rainfall variability in the tropics ( Madden and Julian 1972 ; Zhang 2005 ). While often perceived to be less important over West Africa, the MJO has recently received more attention in the West African monsoon region (WAM; e.g., Sultan et al. 2003 ; Matthews 2004 ; Lavender and Matthews 2009 ) during boreal summer. Most previous work has focused on the mechanisms that affect rainfall variability in

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