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Thomas R. Parish

). It is appropriate to acknowledge the wide variety of local wind maxima described in the literature that have been identified by the term low-level jet (e.g., Stensrud 1996 ). In the discussion that follows, the focus is on the summertime Great Plains nocturnal maximum. Jet profiles linked to transient synoptic disturbances and those tied to the lower branch of a transverse circulation associated with an upper-level jet stream ( Uccellini 1980 ) are not considered. Forcing mechanisms for the

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Yun Lin, Jiwen Fan, Jong-Hoon Jeong, Yuwei Zhang, Cameron R. Homeyer, and Jingyu Wang

forcing and a low background aerosol concentration, we found that the urban aerosol effects on storm intensity and precipitation are much larger than the urban land effect ( Fan et al. 2020 ). Therefore, the relative importance of the urban land effect on storm properties to the urban aerosol effects depends on storm types and associated environmental conditions. We understand the urban land-cover change includes both the surface heat flux change and the surface roughness change. Since the BEP + BEM

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Evgeni Fedorovich, Jeremy A. Gibbs, and Alan Shapiro

). Suggested theories of the LLJ point to the jet being a result of the force imbalance in the atmospheric boundary layer induced by the sudden release of the frictional constraint near sunset ( Blackadar 1957 ). In the case when the synoptic-scale pressure gradient is the dominant forcing, the atmospheric flow response to the force imbalance happens in a form of inertial oscillation. The frictional stress, which was not explicitly considered in the Blackadar analysis, was included in the follow-up study

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Alan Shapiro, Evgeni Fedorovich, and Joshua G. Gebauer

LLJ), or along or north of the intersection of an LLJ with a cold front, are more or less clear, but the mechanisms that force ascent on a lateral flank of an LLJ are still not well understood. In this regard, we believe that the recent Pu and Dickinson (2014) explanation for such a mechanism is not wholly satisfactory. In a study of vertical motions in Great Plains LLJs using a North American Regional Reanalysis (NARR) June–July climatology, Pu and Dickinson (2014) suggest that after midnight

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David B. Parsons, Kevin R. Haghi, Kelton T. Halbert, Blake Elmer, and Junhong Wang

variations in both components of the winds are expected from the recent study by Shapiro et al. (2016) that mathematically unified the inertial oscillation in the ageostrophic component of the NLLJ ( Blackadar 1957 ) with diurnal variations in thermal forcing over sloped terrain ( Holton 1967 ). One difference between Shapiro et al.’s results and the observations in this work is that the observed nocturnal variations in the westerly winds extend throughout the lower troposphere with a minimum between

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Shushi Zhang, David B. Parsons, and Yuan Wang

, black dotted lines indicate the location of a trough at 0100 LST 12 Jun. The dashed black and dashed red rectangles indicate the area shown in Fig. 2 and PECAN domain, respectively. In (b) precipitable water is green shaded (mm), black bold lines indicate the location of a trough at 1900 LST 11 Jun, and the black dashed line indicates the location of the convection initiation at 1700 LST 11 Jun. Without this synoptic forcing, conditions were not conducive for deep convection as the sounding taken

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