Clarifying the Baroclinic Contribution to the Great Plains Low-Level Jet Frequency Maximum

Joshua G. Gebauer School of Meteorology, University of Oklahoma, Norman, Oklahoma

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Alan Shapiro School of Meteorology, and Center for Analysis and Prediction of Storms, University of Oklahoma, Norman, Oklahoma

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Abstract

The frequency and intensity of the Great Plains nocturnal low-level jet (LLJ) are enhanced by baroclinicity over the sloped terrain of the region. A classical description of baroclinic-induced diurnal wind oscillations over the Great Plains considers differential heating of the slope with respect to air at the same elevation far removed from the slope, but with buoyancy constant along the slope (Holton mechanism). Baroclinicity can also occur due to differential heating of the slope itself, which creates a gradient in buoyancy along the slope. The relative prevalence of the two types of baroclinicity in this region has received scant attention in the literature. The present study uses 19 years of data from the Oklahoma Mesonet to evaluate the characteristics of along-slope buoyancy gradients over the region. A mean negative afternoon along-slope buoyancy gradient (east–west gradient) is found over Oklahoma. The sign of this afternoon buoyancy gradient is favorable for LLJ formation, as it results in the strongest southerly geostrophic wind near the ground around sunset, which is conducive to nocturnal jet formation via the inertial oscillation mechanism. The negative afternoon buoyancy gradient is at least partially created by an east–west gradient in diurnal heating and is stronger and more consistent in the summer months, which is when LLJs are most frequent. The contribution of the along-slope buoyancy gradient to the low-level geostrophic wind was found to be as important as the contribution of the Holton mechanism. Overall, these results indicate that along-slope buoyancy gradients should be accounted for in studies of LLJ dynamics over the Great Plains.

© 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Joshua Gebauer, joshua.gebauer@ou.edu

Abstract

The frequency and intensity of the Great Plains nocturnal low-level jet (LLJ) are enhanced by baroclinicity over the sloped terrain of the region. A classical description of baroclinic-induced diurnal wind oscillations over the Great Plains considers differential heating of the slope with respect to air at the same elevation far removed from the slope, but with buoyancy constant along the slope (Holton mechanism). Baroclinicity can also occur due to differential heating of the slope itself, which creates a gradient in buoyancy along the slope. The relative prevalence of the two types of baroclinicity in this region has received scant attention in the literature. The present study uses 19 years of data from the Oklahoma Mesonet to evaluate the characteristics of along-slope buoyancy gradients over the region. A mean negative afternoon along-slope buoyancy gradient (east–west gradient) is found over Oklahoma. The sign of this afternoon buoyancy gradient is favorable for LLJ formation, as it results in the strongest southerly geostrophic wind near the ground around sunset, which is conducive to nocturnal jet formation via the inertial oscillation mechanism. The negative afternoon buoyancy gradient is at least partially created by an east–west gradient in diurnal heating and is stronger and more consistent in the summer months, which is when LLJs are most frequent. The contribution of the along-slope buoyancy gradient to the low-level geostrophic wind was found to be as important as the contribution of the Holton mechanism. Overall, these results indicate that along-slope buoyancy gradients should be accounted for in studies of LLJ dynamics over the Great Plains.

© 2019 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Joshua Gebauer, joshua.gebauer@ou.edu
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  • Astling, E. G., J. Paegle, E. Miller, and C. J. O’Brien, 1985: Boundary layer control of nocturnal convection associated with a synoptic scale system. Mon. Wea. Rev., 113, 540552, https://doi.org/10.1175/1520-0493(1985)113<0540:BLCONC>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bellamy, J. C., 1945: The use of pressure altitude and altimeter corrections in meteorology. J. Meteor., 2, 179, https://doi.org/10.1175/1520-0469(1945)002<0001:TUOPAA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Blackadar, A. K., 1957: Boundary layer wind maxima and their significance for the growth of nocturnal inversions. Bull. Amer. Meteor. Soc., 38, 283290, https://doi.org/10.1175/1520-0477-38.5.283.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bonner, W. D., 1968: Climatology of the low level jet. Mon. Wea. Rev., 96, 833850, https://doi.org/10.1175/1520-0493(1968)096<0833:COTLLJ>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bonner, W. D., and J. Paegle, 1970: Diurnal variations in boundary layer winds over the south-central United States in the summer. Mon. Wea. Rev., 98, 735744, https://doi.org/10.1175/1520-0493(1970)098<0735:DVIBLW>2.3.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Brock, F. V., K. C. Crawford, R. L. Elliot, G. W. Cuperus, S. J. Stadler, H. L. Johnson, and M. D. Eilts, 1995: The Oklahoma Mesonet: A technical overview. J. Atmos. Oceanic Technol., 12, 519, https://doi.org/10.1175/1520-0426(1995)012<0005:TOMATO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Carbone, R. E., J. D. Tuttle, D. A. Ahijevych, and S. B. Trier, 2002: Inferences of predictability associated with warm season precipitation episode. J. Atmos. Sci., 59, 20332056, https://doi.org/10.1175/1520-0469(2002)059<2033:IOPAWW>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Doubler, D., J. Winxler, X. Bian, C. Walters, and S. Zhong, 2015: An NARR-derived climatology of southerly and northerly low-level jets over North America and coastal environs. J. Appl. Meteor. Climatol., 54, 15961619, https://doi.org/10.1175/JAMC-D-14-0311.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Du, Y., and R. Rotunno, 2014: A simple analytical model of the nocturnal low-level jet over the Great Plains of the United States. J. Atmos. Sci., 71, 36743683, https://doi.org/10.1175/JAS-D-14-0060.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fast, J. D., and M. D. McCorcle, 1990: A two-dimensional numerical sensitivity study of the Great Plains low-level jet. Mon. Wea. Rev., 118, 151163, https://doi.org/10.1175/1520-0493(1990)118<0151:ATDNSS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gebauer, J. G., A. Shapiro, E. Fedorovich, and P. Klein, 2018: Convection initiation caused by heterogeneous low-level jets over the Great Plains. Mon. Wea. Rev., 146, 26152637, https://doi.org/10.1175/MWR-D-18-0002.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Higgins, R., Y. Yao, E. Yarosh, J. Janowiak, and K. Mo, 1997: Influence of the Great Plains low-level jet on summertime precipitation and moisture transport over the central United States. J. Climate, 10, 481507, https://doi.org/10.1175/1520-0442(1997)010<0481:IOTGPL>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Holton, J. R., 1967: The diurnal boundary layer wind oscillation above sloping terrain. Tellus, 19, 199205, https://doi.org/10.1111/j.2153-3490.1967.tb01473.x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Maddox, R. A., 1983: Large-scale meteorological conditions associated with midlatitude, mesoscale convective complexes. Mon. Wea. Rev., 111, 14751493, https://doi.org/10.1175/1520-0493(1983)111<1475:LSMCAW>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mahrt, L., 1982: Momentum balance of gravity flows. J. Atmos. Sci., 39, 27012711, https://doi.org/10.1175/1520-0469(1982)039<2701:MBOGF>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McPherson, R. A., and Coauthors, 2007: Statewide monitoring of the mesoscale environment: A technical update on the Oklahoma Mesonet. J. Atmos. Oceanic Technol., 24, 301321, https://doi.org/10.1175/JTECH1976.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nallapareddy, A., A. Shapiro, and J. J. Gourley, 2011: A climatology of nocturnal warming events associated with cold-frontal passages in Oklahoma. J. Appl. Meteor. Climatol., 50, 20422061, https://doi.org/10.1175/JAMC-D-11-020.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Parish, T. R., 2016: A comparative study of the 3 June 2015 Great Plains low-level jet. Mon. Wea. Rev., 144, 29632979, https://doi.org/10.1175/MWR-D-16-0071.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Parish, T. R., 2017: On the forcing of the summertime Great Plains low-level jet. J. Atmos. Sci., 74, 39373953, https://doi.org/10.1175/JAS-D-17-0059.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Parish, T. R., and L. D. Oolman, 2010: On the role of sloping terrain in the forcing of the Great Plains low-level jet. J. Atmos. Sci., 67, 26902699, https://doi.org/10.1175/2010JAS3368.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Parish, T. R., and R. D. Clark, 2017: On the initiation of the 20 June 2015 Great Plains low-level jet. J. Appl. Meteor. Climatol., 56, 18831895, https://doi.org/10.1175/JAMC-D-16-0187.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Parish, T. R., A. R. Rodi, and R. D. Clark, 1988: A case study of the summertime Great Plains low-level jet. Mon. Wea. Rev., 116, 94105, https://doi.org/10.1175/1520-0493(1988)116<0094:ACSOTS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pitchford, K. L., and J. London, 1962: The low-level jet as related to nocturnal thunderstorms over Midwest United States. J. Appl. Meteor., 1, 4347, https://doi.org/10.1175/1520-0450(1962)001<0043:TLLJAR>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rasmusson, E. M., 1967: Atmospheric water vapor transport and the water balance of North America. Part I: Characteristics of the water vapor flux field. Mon. Wea. Rev., 95, 403426, https://doi.org/10.1175/1520-0493(1967)095<0403:AWVTAT>2.3.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Revathy, K., S. R. Prabhakaran Nair, and B. V. Krishna Murthy, 1996: Deduction of temperature profile from MST radar observations of vertical wind. Geophys. Res. Lett., 23, 285288, https://doi.org/10.1029/96GL00086.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rife, D. L., J. O. Pinto, A. J. Monaghan, and C. A. Davis, 2010: Global distribution and characteristic of diurnally varying low-level jets. J. Climate, 23, 50415063, https://doi.org/10.1175/2010JCLI3514.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sangster, W. E., 1960: A method of representing the horizontal pressure force without reduction of station pressures to sea level. J. Meteor., 17, 166176, https://doi.org/10.1175/1520-0469(1960)017<0166:AMORTH>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sangster, W. W., 1967: Diurnal surface geostrophic wind variations over the Great Plains. Proc. Fifth Conf. on Severe Local Storms, St. Louis, MO, Amer. Meteor. Soc., 146–153.

  • Schmid, P., and D. Niyogi, 2012: A method for estimating planetary boundary layer heights and its application over the ARM Southern Great Plains site. J. Atmos. Oceanic Technol., 29, 316322, https://doi.org/10.1175/JTECH-D-11-00118.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schneider, J. M., D. K. Fisher, R. L. Elliott, G. O. Brown, and C. P. Bahrmann, 2003: Spatiotemporal variations in soil water: First results from the ARM SGP CART network. J. Hydrometeor., 4, 106120, https://doi.org/10.1175/1525-7541(2003)004<0106:SVISWF>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Shapiro, A., E. Fedorovich, and S. Rahimi, 2016: A unified theory for the Great Plains nocturnal low-level jet. J. Atmos. Sci., 73, 30373057, https://doi.org/10.1175/JAS-D-15-0307.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Shapiro, A., E. Fedorovich, and J. G. Gebauer, 2018: Mesoscale ascent in nocturnal low-level jets. J. Atmos. Sci., 75, 14031427, https://doi.org/10.1175/JAS-D-17-0279.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Song, J., K. Liao, R. L. Coulter, and B. M. Lesht, 2005: Climatology of the low-level jet at the southern Great Plains Atmospheric Boundary Layer Experiments site. J. Appl. Meteor., 44, 15931606, https://doi.org/10.1175/JAM2294.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Trier, S. B., C. A. Davis, D. A. Ahijevych, M. L. Weisman, and G. H. Bryan, 2006: Mechanisms supporting long-lived episodes of propagating nocturnal convection within a 7-day WRF Model simulation. J. Atmos. Sci., 63, 24372461, https://doi.org/10.1175/JAS3768.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Trier, S. B., C. A. Davis, and R. E. Carbone, 2014: Mechanisms governing the persistence and diurnal cycle of a heavy rainfall corridor. J. Atmos. Sci., 71, 41024126, https://doi.org/10.1175/JAS-D-14-0134.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Tsuda, T., T. E. VanZandt, M. Mizumoto, S. Kato, and S. Fukao, 1991: Spectral analysis of temperature and Brunt-Vaisala frequency fluctuations observed by radiosondes. J. Geophys. Res., 96, 17 26517 278, https://doi.org/10.1029/91JD01944.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Tuttle, J. D., and C. A. Davis, 2006: Corridors of warm season precipitation in the central United States. Mon. Wea. Rev., 134, 22972317, https://doi.org/10.1175/MWR3188.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Walters, C. K., and J. A. Winkler, 2001: Airflow configurations of warm season southerly low-level wind maxima in the Great Plains. Part I: Spatial and temporal relationship to convection. Wea. Forecasting, 16, 513530, https://doi.org/10.1175/1520-0434(2001)016<0513:ACOWSS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Walters, C. K., J. A. Winkler, R. P. Shadbolt, J. van Ravensway, and G. D. Bierly, 2008: A long-term climatology of southerly and northerly low-level jets for the central United States. Ann. Assoc. Amer. Geogr., 98, 521552, https://doi.org/10.1080/00045600802046387.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Whiteman, C. D., X. Bian, and S. Zhong, 1997: Low-level jet climatology from enhanced rawinsonde observations at a site in the southern Great Plains. J. Appl. Meteor., 36, 13631376, https://doi.org/10.1175/1520-0450(1997)036<1363:LLJCFE>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhong, S., J. D. Fast, and X. Bian, 1996: A case study of the Great Plains low-level jet using wind profiler network data and a high-resolution mesoscale model. Mon. Wea. Rev., 124, 785806, https://doi.org/10.1175/1520-0493(1996)124<0785:ACSOTG>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
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