• Acevedo, O. C., L. P. Pezzi, R. B. Souza, V. Anabor, and G. A. Degrazia, 2010: Atmospheric boundary layer adjustment to the synoptic cycle at the Brazil–Malvinas Confluence, South Atlantic Ocean. J. Geophys. Res., 115, D22107, https://doi.org/10.1029/2009JD013785.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Arritt, R. W., T. D. Rink, M. Segal, D. P. Todey, C. A. Clark, M. J. Mitchell, and K. M. Labas, 1997: The Great Plains low-level jet during the warm season of 1993. Mon. Wea. Rev., 125, 21762192, https://doi.org/10.1175/1520-0493(1997)125<2176:TGPLLJ>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Berri, G. J., and B. J. Inzunza, 1993: The effect of the low-level jet on the poleward water vapour transport in the central region of South America. Atmos. Environ., 27A, 335341, https://doi.org/10.1016/0960-1686(93)90107-A.

    • 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.

    • 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
  • Browning, K. A., and C. W. Pardoe, 1973: Structure of low-level jet streams ahead of mid-latitude cold fronts. Quart. J. Roy. Meteor. Soc., 99, 619638, https://doi.org/10.1002/qj.49709942204.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Campetella, C. M., and C. S. Vera, 2002: The influence of the Andes mountains on the South American low-level flow. Geophys. Res. Lett., 29, 1826, https://doi.org/10.1029/2002GL015451.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Campos, C. R. J., and J. G. M. Santos, 2007: Seasonal climatology of the low-level jet in the Porto Alegre metropolitan area for the 1989 to 2003 period utilizing rawinsonde data (in Portuguese). Anuar. Inst. Geoc. UFRJ, 30, 8392, https://revistas.ufrj.br/index.php/aigeo/article/view/6770.

    • Search Google Scholar
    • Export Citation
  • Chen, R., and L. Tomassini, 2015: The role of moisture in summertime low-level jet formation and associated rainfall over the East Asian monsoon region. J. Atmos. Sci., 72, 38713890, https://doi.org/10.1175/JAS-D-15-0064.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Doswell, C. A., III, 1991: A review for forecasters on the application of hodographs to forecasting severe thunderstorms. Natl. Wea. Dig., 16, 216.

    • 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
  • Du, Y., Q. Zhang, Y. L. Chen, Y. Zhao, and X. Wang, 2014: Numerical simulations of spatial distributions and diurnal variations of low-level jets in China during early summer. J. Climate, 27, 57475767, https://doi.org/10.1175/JCLI-D-13-00571.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Garratt, J. R., 1985: The inland boundary layer at low latitudes. Part I. The nocturnal jet. Bound.-Layer Meteor., 32, 307327, https://doi.org/10.1007/BF00121997.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Garreaud, R. D., 2000: Cold air incursions over subtropical South America: Mean structure and dynamics. Mon. Wea. Rev., 128, 25442559, https://doi.org/10.1175/1520-0493(2000)128<2544:CAIOSS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Garreaud, R. D., and R. C. Muñoz, 2005: The low-level jet off the west coast of subtropical South America: Structure and variability. Mon. Wea. Rev., 133, 22462261, https://doi.org/10.1175/MWR2972.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gebauer, J. G., E. Fedorovich, and A. Shapiro, 2017: A 1-D theoretical analysis of the northerly low-level jets over the Great Plains. J. Atmos. Sci., 74, 34193431, https://doi.org/10.1175/JAS-D-16-0333.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hoecker, W. H., 1963: Three southerly low-level jet systems delineated by the weather Bureau Special Pibal Network of 1961. Mon. Wea. Rev., 91, 573582, https://doi.org/10.1175/1520-0493(1963)091<0573:TSLJSD>2.3.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Holton, J. R., 1967: The diurnal boundary layer wind oscillation above sloping terrain. Tellus, 19, 200205, https://doi.org/10.3402/tellusa.v19i2.9766.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jiang, X., N. Lau, I. M. Held, and J. J. Ploshay, 2007: Mechanisms of the Great Plains low-level jet as simulated in an AGCM. J. Atmos. Sci., 64, 532547, https://doi.org/10.1175/JAS3847.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77, 437471, https://doi.org/10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Liu, H., M. He, B. Wang, and Q. Zhang, 2014: Advances in low-level jet research and future prospects. J. Meteor. Res., 28, 5775.

  • Marengo, J. A., W. R. Soares, C. Saulo, and M. Nicolini, 2004: Climatology of the low-level jet east of the Andes as derived from the NCEP–NCAR reanalyses: Characteristics and temporal variability. J. Climate, 17, 22612280, https://doi.org/10.1175/1520-0442(2004)017<2261:COTLJE>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marengo, J. A., M. W. Douglas, and P. L. Silva Dias, 2002: The South American low-level jet east of the Andes during the 1999 LBA-TRMM and LBA-WET AMC campaign. J. Geophys. Res., 107, 8079, https://doi.org/10.1029/2001JD001188.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Markowski, P., and Y. Richardson, 2010: Mesoscale Meteorology in Midlatitudes. Wiley-Blackwell, 424 pp.

    • Crossref
    • Export Citation
  • Montini, T., C. Jones, and L. V. Carvalho, 2016: The South American low-level jet: A new climatology, variability, and changes. 2016 Fall Meeting, San Francisco, CA, Amer. Geophys. Union, Abstract A11N-0198.

  • Muñoz, R. C., and R. D. Garreaud, 2005: Dynamics of the low-level jet off the west coast of subtropical South America. Mon. Wea. Rev., 133, 36613677, https://doi.org/10.1175/MWR3074.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nascimento, E. L., G. Held, and A. M. Gomes, 2014: A multiple-vortex tornado in southeastern Brazil. Mon. Wea. Rev., 142, 30173037, https://doi.org/10.1175/MWR-D-13-00319.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nascimento, E. L., M. Foss, V. Ferreira, and H. E. Brooks, 2016: An updated and expanded climatology of severe weather parameters for subtropical South America as derived from upper air observations and CFSR-CFSv2 data. 28th Conf. on Severe Local Storms, Portland, OR, Amer. Meteor. Soc., 18.5, https://ams.confex.com/ams/28SLS/webprogram/Paper300887.html.

  • Nascimento, M. G., D. L. Herdies, and D. O. Souza, 2016: The South American water balance: The influence of low-level jets. J. Climate, 29, 14291449, https://doi.org/10.1175/JCLI-D-15-0065.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nicolini, M., and A. C. Saulo, 2000: Eta characterization of the 1997-1998 warm season Chaco jet cases. Sixth Int. Conf. on Southern Hemisphere Meteorology and Oceanography, Santiago, Chile, Amer. Meteor. Soc., 12C.1, https://ams.confex.com/ams/other/techprogram/paper_10722.htm.

  • Nicolini, M., P. Salio, G. Ulke, J. Marengo, M. Douglas, J. Paegle, and E. Zipser, 2004: South American low-level jet diurnal cycle and three-dimensional structure. CLIVAR Exchanges, Vol. 9, International CLIVAR Project Office, Southampton, United Kingdom, 6–8.

  • Oliveira, M. I., F. S. Puhales, E. L. Nascimento, and V. Anabor, 2016: Observations and predictability analysis of the 20 April 2015 Xanxere tornado in southern Brazil. 28th Conf. on Severe Local Storms, Portland, OR, Amer. Meteor. Soc., 5, https://ams.confex.com/ams/28SLS/webprogram/Paper301808.html.

  • 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
  • Pereira, A. P., G. A. Degrazia, O. L. L. Moraes, and T. Tirabassi, 1995: Numerical study of the nocturnal planetary boundary layer at low latitudes. Air Pollution III, Volume 1, Theory and Simulation, C. A. Brebbia, H. Power, and N. Moussiopoulos, Eds., WIT Press, 167–174.

  • Rasmussen, K. L., and R. A. Houze Jr., 2011: Orogenic convection in subtropical South America as seen by the TRMM satellite. Mon. Wea. Rev., 139, 23992420, https://doi.org/10.1175/MWR-D-10-05006.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rasmussen, K. L., and R. A. Houze Jr., 2016: Convective initiation near the Andes in subtropical South America. Mon. Wea. Rev., 144, 23512374, https://doi.org/10.1175/MWR-D-15-0058.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rasmussen, K. L., M. D. Zuluaga, and R. A. Houze Jr., 2014: Severe convection and lightning in subtropical South America. Geophys. Res. Lett., 41, 73597366, https://doi.org/10.1002/2014GL061767.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Repinaldo, H. F. B., M. Nicolini, and Y. G. Skabar, 2015: Characterizing the diurnal cycle of low-level circulation and convergence using CFSR data in southeastern South America. J. Appl. Meteor. Climatol., 54, 671690, https://doi.org/10.1175/JAMC-D-14-0114.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rife, D. L., J. O. Pinto, A. J. Monagham, C. A. Davis, and J. R. Hannan, 2010: Global distribution and characteristics of diurnally varying low-level jets. J. Climate, 23, 50415064, https://doi.org/10.1175/2010JCLI3514.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Romatschke, U., and R. A. Houze Jr., 2010: Extreme summer convection in South America. J. Climate, 23, 37613791, https://doi.org/10.1175/2010JCLI3465.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Saha, S., and Coauthors, 2010: The NCEP Climate Forecast System Reanalysis. Bull. Amer. Meteor. Soc., 91, 10151057, https://doi.org/10.1175/2010BAMS3001.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Salio, P., M. Nicolini, and A. C. Saulo, 2002: Chaco low-level jet events characterization during the austral summer season. J. Geophys. Res., 107, 4816, https://doi.org/10.1029/2001JD001315.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Salio, P., M. Nicolini, and E. J. Zipser, 2007: Mesoscale convective systems over southeastern South America and their relationship with the South American low-level jet. Mon. Wea. Rev., 135, 12901309, https://doi.org/10.1175/MWR3305.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Saulo, A. C., M. Nicolini, and S. C. Chou, 2000: Model characterization of the South American low-level flow during the 1997–1998 spring–summer season. Climate Dyn., 16, 867881, https://doi.org/10.1007/s003820000085.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Saulo, A. C., M. E. Seluchi, and M. Nicolini, 2004: A case study of a Chaco low-level jet event. Mon. Wea. Rev., 132, 26692683, https://doi.org/10.1175/MWR2815.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Saulo, A. C., J. Ruiz, and Y. G. Skabar, 2007: Synergism between the low-level jet and organized convection at its exit region. Mon. Wea. Rev., 135, 13101326, https://doi.org/10.1175/MWR3317.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Seluchi, M. E., A. C. Saulo, M. Nicolini, and P. Satyamurty, 2003: The northwestern Argentinean low: A study of two typical events. Mon. Wea. Rev., 131, 23612378, https://doi.org/10.1175/1520-0493(2003)131<2361:TNALAS>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
  • Sperling, V. B., 2018: Physical and Electrical Processes in Hailstorms in Southern Brazil (in Portuguese). Ph.D. thesis, Instituto Nacional de Pesquisas Espaciais, São José dos Campos, Brazil, 187 pp.

  • Stensrud, D. J., 1996: Importance of low-level jets to climate: A review. J. Climate, 9, 16981711, https://doi.org/10.1175/1520-0442(1996)009<1698:IOLLJT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Teixeira, M. S., and P. Satyamurty, 2007: Dynamical and synoptic characteristics of heavy rainfall episodes in Southern Brazil. Mon. Wea. Rev., 135, 598617, https://doi.org/10.1175/MWR3302.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Uccellini, L. W., 1980: On the role of upper tropospheric jet streaks and leeside cyclogenesis in the development of low-level jets in the Great Plains. Mon. Wea. Rev., 108, 16891696, https://doi.org/10.1175/1520-0493(1980)108<1689:OTROUT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vera, C., P. K. Vigliarolo, and E. H. Berbery, 2002: Cold-season synoptic scale waves over subtropical South America. Mon. Wea. Rev., 130, 684699, https://doi.org/10.1175/1520-0493(2002)130<0684:CSSSWO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vera, C., and Coauthors, 2006: The South American low-level jet experiment. Bull. Amer. Meteor. Soc., 87, 6377, https://doi.org/10.1175/BAMS-87-1-63.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Weykamp, F. V., and T. Ambrizzi, 2006: The role of the low-level jet east of the Andes in extreme rainfall events over southern South America. Eighth Int. Conf. on Southern Hemisphere Meteorology and Oceanography, Foz do Iguaçu, Brazil, Amer. Meteor. Soc., 1231–1234.

  • 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
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 599 360 53
PDF Downloads 474 225 18

A New Look at the Identification of Low-Level Jets in South America

View More View Less
  • 1 Grupo de Modelagem Atmosférica, Departamento de Física, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, Brazil
© Get Permissions Rent on DeepDyve
Restricted access

Abstract

Criteria currently employed in algorithms that identify low-level jets (LLJs) in South America utilizing rawinsonde and gridded model data fail to detect an important number of LLJ events. This study discusses shortcomings in the existing approaches for LLJ identification in South America and proposes modifications to the criteria regarding layer depth for LLJ identification and wind direction. Episodes of southerly LLJs, which have received less attention in the La Plata basin, are also included in the investigation. A sensitivity analysis of LLJ detection in South America upon the choice of the criteria applied to a sample period of 15 years (1996–2010) of gridded numerical data from the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR), and to a 20-yr dataset (1996–2015) of actual rawinsondes for the La Plata basin, reveals the benefits of revising the criteria. The modified criteria allow for the characterization of a wider spectrum of LLJs over key regions of South America, such as over the Bolivian–Paraguayan border, Sierras de Córdoba in Argentina, and southern-southeastern Brazil. This wider range of events includes elevated LLJs, mostly with strong zonal components, that account for approximately 20% of the full sample of LLJs identified in the rawinsonde dataset investigated here. The revised criteria have the advantage of retaining the identification of episodes that meet the consecrated definition of the South American LLJ, while at the same time providing an augmented sample of such wind systems. Our results provide further insights into the forcing mechanisms of distinct types of LLJs in South America, ranging from topographic to baroclinic effects.

Current affiliation: Center for Analysis and Prediction of Storms, and School of Meteorology, University of Oklahoma, Norman, Oklahoma.

© 2018 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: Maurício I. Oliveira, mauricio.meteorologia@gmail.com

Abstract

Criteria currently employed in algorithms that identify low-level jets (LLJs) in South America utilizing rawinsonde and gridded model data fail to detect an important number of LLJ events. This study discusses shortcomings in the existing approaches for LLJ identification in South America and proposes modifications to the criteria regarding layer depth for LLJ identification and wind direction. Episodes of southerly LLJs, which have received less attention in the La Plata basin, are also included in the investigation. A sensitivity analysis of LLJ detection in South America upon the choice of the criteria applied to a sample period of 15 years (1996–2010) of gridded numerical data from the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR), and to a 20-yr dataset (1996–2015) of actual rawinsondes for the La Plata basin, reveals the benefits of revising the criteria. The modified criteria allow for the characterization of a wider spectrum of LLJs over key regions of South America, such as over the Bolivian–Paraguayan border, Sierras de Córdoba in Argentina, and southern-southeastern Brazil. This wider range of events includes elevated LLJs, mostly with strong zonal components, that account for approximately 20% of the full sample of LLJs identified in the rawinsonde dataset investigated here. The revised criteria have the advantage of retaining the identification of episodes that meet the consecrated definition of the South American LLJ, while at the same time providing an augmented sample of such wind systems. Our results provide further insights into the forcing mechanisms of distinct types of LLJs in South America, ranging from topographic to baroclinic effects.

Current affiliation: Center for Analysis and Prediction of Storms, and School of Meteorology, University of Oklahoma, Norman, Oklahoma.

© 2018 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: Maurício I. Oliveira, mauricio.meteorologia@gmail.com
Save