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L. M. Ivanov, C. A. Collins, and T. M. Margolina

1. Introduction In recent years there has been growing recognition of the existence of large-scale coherent quasi-zonal jets in the atmosphere and oceans of the earth as well as in the atmospheres of gaseous planets ( Rhines 1975 ; Williams 1978 ; Panetta 1993 ; Onishenko et al. 2004 ; Galperin et al. 2006 ; Nadiga 2006 ; Baldwin et al. 2007 ; Huang et al. 2007 ; Maximenko et al. 2008 ; Ivanov et al. 2009 ; Berloff et al. 2009 ; van Sebille et al. 2011 among others). In atmospheres

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Seung-Bum Kim and M. A. Saunders

method. Developments since the original KG model formulation include the introduction of two-dimensional objective mapping ( Qiu et al. 1991 ), the development of a criterion to quantify the jet's meandering ( Qiu 1992 ), the attempt to model recirculation ( Qiu 1992 ), and the use of double-Gaussian modeling ( Gille 1994 ). Despite these innovations, the method has its shortcomings as we now identify. First, we find that the details of the smoothing filter used to presmooth the noisy altimeter

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Michael Tjernström and Carl A. Friehe

FEBRUARY 1991 MICHAEL TJERNSTRI)M AND CARL A. FRIEHE 19Analysis of a Radome Air-Motion System on a Twin-Jet Aircraft for Boundary-Layer Research MICHAEL TJERNSTROM* AND CARL A, FRIEHEt * Department of Meteorology, Uppsala University, Uppsala, Sweden*Department of Mechanical Engineering. University of CaliJbrnia, Irvine, California (Manuscript received 2 February 1990, in final form 21 June 1990

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Yelena L. Pichugina, Sara C. Tucker, Robert M. Banta, W. Alan Brewer, Neil D. Kelley, Bonnie J. Jonkman, and Rob K. Newsom

in this case, reasonable periods of acceptably stationary behavior might be definable. The speed of the low-level jet (LLJ), which drives the dynamics of this boundary layer ( Banta et al. 2006 , hereafter BPB06 ), has been observed to vary slowly in time or even remain constant on some nights, and its mean properties have been observed to be constant over areas of a few tens to a few hundred kilometers across ( Banta et al. 2002 ; Song et al. 2005 ). Flow properties in the subjet layer

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Margarita A. Kallistratova, Rostislav D. Kouznetsov, Valerii F. Kramar, and Dmitrii D. Kuznetsov

turbulence ( Baas et al. 2010 ). The low-level jet (LLJ) is a flow, specific to stable ABLs, that has a distinct maximum of wind speed within a few hundreds of meters above ground. LLJs form in stably stratified atmospheres resulting from the small vertical exchange between atmospheric layers that favor the formation of wind shears. LLJs can originate from local circulations because of orography and/or thermal inhomogeneity of the ground surface, from inertial oscillations resulting from the nocturnal

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Thomas R. Parish, Matthew D. Burkhart, and Alfred R. Rodi

terrain datasets, allows the height of the underlying terrain to be determined. The radar altitude of the aircraft is added to the terrain height, giving an absolute measure of the height of the isobaric surface, and hence the slope of the surface can be determined. A schematic of the process and an example from the 1983 low-level jet (LLJ) study in Oklahoma described by Parish et al. (1988) are illustrated in Fig. 1 . Several difficulties must be overcome to ensure accurate detection of the

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Len Zedel and Alex E. Hay

-scale structures, suggestive of turbulence. Remote measurements of turbulence and small-scale velocity shear require verification. For this purpose, we have chosen to investigate the performance of the coherent Doppler profiler in a well-studied turbulent shear flow: a round jet (see List 1982 ; Hussein et al. 1994 ). The purpose of this paper is to present the results of this investigation. The experiments were carried out in a particle-laden jet using natural sand with a nominal median diameter of 180 μ m

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David J. Stensrud, Michael H. Jain, Kenneth W. Howard, and Robert A. Maddox

assess the potential for Next Generation WeatherRadar (NEXRAD), 404-MHz radar wind profilers, and digital sounding systems to monitor the low-level windfield during clear-air conditions. The low-level jet was chosen as the phenomenon of interest because it is neitherwell sampled nor resolved by the current upper-air network, yet it is a common feature of mesoscale convectivesystem and severe thunderstorm environments. Data were collected under quiescent synoptic conditions duringseveral low-level jet

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Mohammad Kazemi, Babak Khorsandi, and Laurent Mydlarski

its effect on the Doppler noise ( Lohrmann et al. 1994 ), no thorough studies have been conducted on the effect of the sampling volume size on the mean and turbulence statistics measured by ADVs. Moreover, ADVs have been almost exclusively benchmarked in open-channel flows ( Lhermitte and Lemmin 1994 ; Voulgaris and Trowbridge 1998 ; McLelland and Nicholas 2000 ; Hurther and Lemmin 2001 ; Valero and Bung 2018 ). Benchmarking ADVs in free-shear flows, like turbulent jets, which have been

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Olga P. Verkhoglyadova, Stephen S. Leroy, and Chi O. Ao

January–February, is at 200 hPa. Figure 3d shows subtropical RMS, which is substantially larger (≈4.5 m s −1 ) than the global RMS ageostrophy error. The ageostrophy error is largest around altitudes of the subtropical jet (150–250 hPa; see also Davis and Birner 2013 ). Fig . 3. Ageostrophy error. Difference between reference ERA-interim winds and ERA-Interim-derived geostrophic winds (m s −1 ) at constant kinetic pressure surfaces at 200-hPa constant pressure surface for (a) January and (b) July

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