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Joshua G. Gebauer and Alan Shapiro

1. Introduction Climatological studies have revealed a well-defined maximum in the frequency and intensity of southerly low-level wind maxima over the southern Great Plains ( Bonner 1968 ; Walters et al. 2008 ; Rife et al. 2010 ; Doubler et al. 2015 ). This phenomenon has been named the Great Plains low-level jet (LLJ). The LLJ is primarily a nocturnal feature and typically occurs below 1000 m, with a peak wind often just a few hundreds of meters above the ground. The LLJ plays an important

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Anandakumar Karipot, Monique Y. Leclerc, and Gengsheng Zhang

1. Introduction Low-level jets are important atmospheric processes frequently observed in the earth’s planetary boundary layer. A low-level jet (LLJ) generally forms during the evening, strengthens during the course of the night, and dissipates shortly after sunrise because of enhanced vertical mixing generated by the warming of the surface. One of the pioneering theories on the LLJ formation is Blackadar’s (1957) inertial oscillation mechanism associated with frictional decoupling during

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Isabella Bordi, Klaus Fraedrich, Frank Lunkeit, and Alfonso Sutera

1. Introduction The most prominent feature of the general circulation is the presence of a mean westerly jet at the tropopause level in the Tropics. Moreover, when we consider, for example, the observed Northern Hemisphere zonally averaged zonal wind standard deviation, we find two relative maxima located in the subtropics and midlatitudes. Thus, a central problem is the finding of the physical mechanisms that originate and maintain these observed features. Since the works of Rossby and Starr

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Brian A. Colle and David R. Novak

scale larger than a typical sea breeze (i.e., 100–200 km). Such coastal flows may be influenced by differential surface heating and coastal geometry, as well as the Appalachian terrain farther inland ( Fig. 1a ). The goal of this study is to investigate a coastal low-level jet that develops primarily during the spring and summer months, in which relatively strong (>11 m s −1 ) southerly winds occur in the New York Bight (NYB; the offshore region bounded by the northern New Jersey and Long

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Celeste Saulo, Juan Ruiz, and Yanina García Skabar

1. Introduction Recent studies related to the South America Low-Level Jet (SALLJ) have been focused on describing its mean features using gridded analyses ( Marengo et al. 2004 ; Salio et al. 2002 , and references therein), with an emphasis on the assessment of how this low-level wind flow affects the moisture balance of one of the richest agricultural basins in the world—the La Plata basin. Also, dynamical downscaling has been the choice to document the smaller-scale characteristics of this

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Zachary J. Handlos and Jonathan E. Martin

1. Introduction The genesis, evolution, and dissipation of extratropical weather systems and related midlatitude phenomena are often linked to the evolution of the Northern Hemisphere polar and subtropical jet streams, which have been researched extensively over the past several decades. The polar jet resides above regions of strong baroclinicity within the midlatitudes (usually poleward of 30° latitude), and its speed maxima is observed ~300 hPa. The polar jet is also referred to as the “eddy

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Mark W. Seefeldt and John J. Cassano

Liu 1996 ). The observations indicated the presence of a low-level jet (LLJ) approximately 200 m above ground level (AGL) with increasing intensity toward the Transantarctic Mountains. The increased use of numerical simulations has provided more insight into the low-level wind field. Seefeldt et al. (2003) discuss the complex structure of the low-level wind field in the widely varying topography of the northwest Ross Ice Shelf. Numerical simulations of LLJs near the northern west coast of the

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Joseph B. Olson and Brian A. Colle

1. Introduction The low-level flow from the Pacific Ocean interacts with the steep coastal terrain of Alaska to create strong (>25 m s −1 ) terrain-parallel winds ( Overland and Bond 1995 ; Loescher et al. 2006 ; Colle et al. 2006 ; Olson et al. 2007 ; among others) known as barrier jets ( Schwerdtfeger 1974 ; Overland and Bond 1993 , 1995 ). These jets can result in enhanced turbulence ( Smedman et al. 1995 ; Bond and Walter 2002 ) and wind stress forcing of local currents and storm

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Yu Du, Guixing Chen, Bin Han, Chuying Mai, Lanqiang Bai, and Minghua Li

2005 ; Keene and Schumacher 2013 ; Liu et al. 2018 ), and terrain effects ( Wang et al. 2014 ; Mulholland et al. 2019 ). In contrast, CI and UCG away from surface boundaries often occur during the night, and their mesoscale and small-scale features are poorly captured by numerical models ( Wilson and Roberts 2006 ; Davis et al. 2003 ). Nocturnal CI and UCG are typically associated with low-level jets ( Du and Chen 2019a ; Gebauer et al. 2018 ; Trier et al. 2017 ; Shapiro et al. 2018 ) and

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Joshua G. Gebauer, Alan Shapiro, Evgeni Fedorovich, and Petra Klein

the region. The thunderstorms are often elevated, in the sense that storm updrafts develop in an elevated region separated from the surface by a nocturnal stable boundary layer ( Colman 1990 ; Wilson and Roberts 2006 ). One feature associated with the initiation and development of these nocturnal thunderstorms is the Great Plains low-level jet (LLJ) ( Pitchford and London 1962 ; Maddox 1983 ; Astling et al. 1985 ; Trier and Parsons 1993 ; Trier et al. 2006 ; Tuttle and Davis 2006 ). LLJs are

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