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Xianan Jiang, Ngar-Cheung Lau, Isaac M. Held, and Jeffrey J. Ploshay

1. Introduction During the summer months from April to September, the Great Plains of the United States are characterized by the frequent occurrence of a southerly low-level jet (LLJ). This LLJ is mainly confined in the boundary layer with maximum wind speeds typically at 500–1000 m above the ground. The jet exhibits strong diurnal oscillation, with the strongest wind speed mostly occurring during the night. This Great Plains LLJ has been intensively documented during the past decades (e

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Amanda K. O’Rourke and Geoffrey K. Vallis

1. Introduction The identification of the subtropical and eddy-driven jets as two related, but separate and distinct, features of the midlatitude atmosphere has received increasing research attention over the past decade ( Lee and Kim 2003 ; Kim and Lee 2004 ; Vallis 2006 ). The classical approach to the general circulation of the midlatitude atmosphere is to describe the movement of a single “jet stream” corresponding to the single maximum in zonal-mean zonal wind. However, this single-jet

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Thomas R. Parish

1. Introduction The Great Plains Turbulence Research Program was a major field experiment conducted near the town of O’Neill in north-central Nebraska from August through September of 1953 ( Lettau and Davidson 1957 ). A recurring lower-atmospheric feature documented during that study was what is now known as the Great Plains low-level jet (LLJ). Lettau (1967) noted that the LLJ occurred regularly at an elevation about 450 m above the ground, commencing after sunset and reaching a peak speed

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Mikio Nakanishi, Ryosuke Shibuya, Junshi Ito, and Hiroshi Niino

(1979) showed universal characteristics of turbulent statistics based on observations, Schmidt and Schumann (1989) exhibited polygonal cells and their coherency using LES, and Weckwerth et al. (1997) suggested environmental conditions determining features of horizontal convective rolls based on observations and simulations. In the SBL, on the other hand, turbulence becomes weak or intermittent, and its dominant scales decrease. Also the presence of internal gravity waves, low-level jets (LLJs

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Navid C. Constantinou, Brian F. Farrell, and Petros J. Ioannou

1. Introduction A regime in which jets, planetary-scale waves, and vortices coexist is commonly observed in the turbulence of planetary atmospheres, with the banded winds and embedded vortices of Jupiter and the Saturn North Polar vortex constituting familiar examples ( Vasavada and Showman 2005 ; Sánchez-Lavega et al. 2014 ). Planetary-scale waves in the jet stream and vortices, such as cutoff lows, are also commonly observed in Earth’s atmosphere. Conservation of energy and enstrophy in

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Panos J. Athanasiadis, John M. Wallace, and Justin J. Wettstein

explore the use of empirical orthogonal function (EOF) analysis of zonal wind variability at the jet stream level as a basis for defining extratropical wintertime climate patterns. The analysis is performed separately in the North Atlantic and North Pacific sectors. In section 2 we describe the dataset and the data processing methodology. In section 3 we examine the statistics (mean and variance) of the 250-hPa zonal wind field and compare the teleconnectivity maps for the latter field and the 500

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Ben Harvey, John Methven, and Maarten H. P. Ambaum

1. Introduction Rossby waves are a ubiquitous feature of the extratropical atmosphere, as evidenced by the perpetual north–south meandering of the midlatitude jet streams. Due to the dominant dynamical role they play in the large-scale evolution of the atmosphere, including extratropical cyclone development, blocking episodes, and teleconnection patterns, a good representation of Rossby waves is a crucial requirement for accurate simulations in both numerical weather prediction (NWP) and

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Mara Felici, Valerio Lucarini, Antonio Speranza, and Renato Vitolo

with respect to T E is also analyzed in this section. Section 5 summarizes the results and their relation to the above discussion. The model of the baroclinic jet used as a stochastic generator is described in the appendix , referring to Lucarini et al. (2005) for a thorough discussion. 2. Data and methods a. Total energy of the atmospheric model We consider a quasigeostrophic intermediate complexity model ( Speranza and Malguzzi 1988 ; Malguzzi et al. 1990 ; Lucarini et al. 2005 ; also

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M. Roja Raman, M. Venkat Ratnam, M. Rajeevan, V. V. M. Jagannadha Rao, and S. Vijaya Bhaskara Rao

1. Introduction Monsoon dynamics play an important role in determining the amount of precipitation/rainfall across the country during the southwestern monsoon. Among many dynamical parameters, the strong cross-equatorial flow in the lower troposphere widely known as the monsoon low-level jet (MLLJ) plays an important role on the Indian summer monsoon (ISM) rainfall, which occurs during June–September. The strong cross-equatorial flow, which is the manifestation of large thermal gradients

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Dehai Luo, Tingting Gong, and Yina Diao

Hartmann 2001 ). DeWeaver and Nigam (2000a , b ) noted that during the NAO life cycle, stationary waves contribute more importantly to the zonal-mean jet anomalies than synoptic-scale eddies in NH winters. However, Lorenz and Hartmann (2003) found that in NH winter quasi-stationary waves can reinforce the zonal wind anomalies, but baroclinic eddies seem more important. The distinction between the subtropical jet and the eddy-driven midlatitude jet is less clear compared to the SH ( Bals-Elsholz et

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