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Thara V. Prabha, Monique Y. Leclerc, Anandakumar Karipot, and David Y. Hollinger

; Coulter and Doran 2002 ; Doran 2004 ), such as wave–turbulence interactions ( Einaudi and Finnigan 1993 ), shear-flow instability ( Newsom and Banta 2002 ), density currents ( Sun et al. 2002 ), downward-propagating solitary and internal gravity waves ( Sun et al. 2004 ), and low-level jets (LLJs; Banta et al. 2002 ). In the presence of an LLJ, SBLs are often coupled with upside-down boundary layers ( Mahrt 1999 ; Mahrt and Vickers 2002 ). The turbulence is generated at elevated layers by high wind

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Tsing-Chang Chen, Shih-Yu Wang, and Adam J. Clark

et al. 1988 ; Lau and Lau 1990 ) and modern reanalyses (e.g., Pytharoulis and Thorncroft 1999 ; Fink et al. 2004 ). The northern track appears to be underneath the midtropospheric Saharan high, north of the African easterly jet, while the southern track lies along the south side of the African easterly jet. Reed et al. (1988) observed that the population of AEW n s is likely larger than AEW S s, while Chen (2006) estimated that the ratio between populations of AEW n and AEW s is 2.5: 1

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D. Whittleston, S. E. Nicholson, A. Schlosser, and D. Entekhabi

hypotheses were rejected at α FDR = 0.05. 3. Jet dynamics and rainfall Remote forcing may be viewed as the initial step in a complex teleconnections chain that forces Sahel rainfall variability. The latitudinal bounds of the tropical easterly jet (TEJ) and African easterly jet (AEJ) delineate a significant region of African easterly wave (AEW) activity, vertical motion, and the tropical rain belt, which ultimately delivers rainfall to the region. These zonal jets are key for supplying energy to the

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Levi P. Cowan and Robert E. Hart

1. Introduction Upper-tropospheric jets are among the most conspicuous environmental asymmetries that influence tropical cyclones (TCs), and have been argued to do so through a multitude of physical processes. While prior work has examined TC–jet interactions in case studies and modeling experiments, no systematic identification and cataloging of jets in proximity to TCs has been performed. Such a dataset would prove useful for analyzing specific TC–jet configurations and studying how TCs

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Jessica D. Lundquist, Justin R. Minder, Paul J. Neiman, and Ellen Sukovich

observations [Parameter-Elevation Regressions on Independent Slopes Model (PRISM); Daly et al. 1994 ]. Second, we examine how processes not included in the idealized model, specifically blocking as characterized by the Sierra barrier jet (SBJ), relate to spatial patterns of precipitation. Finally, we discuss implications for basin hydrology. Throughout the paper, we discuss spatial patterns but particular emphasis is put on variations in precipitation accumulation with elevation, since this has the

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Ernesto Muñoz, Antonio J. Busalacchi, Sumant Nigam, and Alfredo Ruiz-Barradas

1. Introduction Low-level jets (LLJs) are regional maxima of winds in the lower troposphere ( Stensrud 1996 ). Two prominent LLJs in the Americas are the Great Plains LLJ (GPLLJ; Helfand and Schubert 1995 ; Ting and Wang 2006 ) and the South American LLJ (SALLJ; Berbery and Collini 2000 ; Vera et al. 2006 ). Whereas a body of research has developed over the past decade regarding the GPLLJ and the SALLJ, the easterly LLJ over the Caribbean Sea has remained understudied. With a peak during

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Stephanie Leroux and Nicholas M. J. Hall

African easterly jet (AEJ). Many studies have focused on these African synoptic-scale perturbations since the 1970s and the Global Atmospheric Research Program (GARP) Atlantic Tropical Experiment (GATE) campaign (e.g., Burpee 1972 ; Reed et al. 1969). Motivations for a better understanding of easterly waves are strong because these waves are associated with modulation of convection and rainfall over West Africa (e.g., Duvel 1990 ; Fink and Reiner 2003 ; Kiladis et al. 2006 ) and with the genesis

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Daran L. Rife, James O. Pinto, Andrew J. Monaghan, Christopher A. Davis, and John R. Hannan

1. Introduction Worldwide, a central influence on human activity is rainfall that derives from transport of water vapor from low to high latitudes or directly from warm oceans inland over continents. Much of this transport occurs in confined wind corridors termed generically as low-level jets (LLJs). As outlined in the review by Stensrud (1996 , hereafter S96) , these jets take many forms. In extratropical cyclones, atmospheric rivers have been identified ( Newell et al. 1992 ; Ralph et al

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Man-Li C. Wu, Oreste Reale, Siegfried D. Schubert, Max J. Suarez, and Chris D. Thorncroft

approaches, ranging from properties of the African easterly jet (AEJ) affecting wave development, intrinsic properties of the waves, mechanisms affecting the intensification of waves, to the actual occurrence of tropical cyclones (TCs). Notwithstanding the complexity of the tropical genesis and development problem and the prominent roles of vertical stability and precursor disturbances, it is widely accepted that sea surface temperatures and vertical shear (e.g., Shapiro and Goldenberg 1998 ; Aiyyer

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D. G. Dritschel and M. E. McIntyre

stratified, rotating systems, are three interrelated phenomena on which this review will focus: first the spatial inhomogeneity of PV mixing by layerwise-two-dimensional turbulence, second the common occurrence of “antifrictional” or upgradient horizontal stresses , and third the spontaneous creation and self-sharpening, or narrowing, of jets. The three phenomena are all illustrated by the typical jet-sharpening scenario sketched in Fig. 1 . The sketch was originally made to help understand the

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