• Anabor, V., D. J. Stensrud, and O. L. L. De Moraes, 2008: Serial upstream-propagating mesoscale convective system events over southeastern South America. Mon. Wea. Rev., 136, 30873105, https://doi.org/10.1175/2007MWR2334.1.

    • 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
  • Borque, P., P. Salio, M. Nicolini, and Y. G. Skabar, 2010: Environment associated with deep moist convection under SALLJ conditions: A case study. Wea. Forecasting, 25, 970984, https://doi.org/10.1175/2010WAF2222352.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Byerle, L. A., and J. Paegle, 2002: Description of the seasonal cycle of low-level flows flanking the Andes and their interannual variability. Meteorologica, 27, 7188.

    • 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, 69, https://doi.org/10.1029/2002GL015451.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Carril, A. F., and Coauthors, 2012: Performance of a multi-RCM ensemble for South Eastern South America. Climate Dyn., 39, 27472768, https://doi.org/10.1007/s00382-012-1573-z.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Carvalho, L. M. V., and C. Jones, 2001: A satellite method to identify structural properties of mesoscale convective systems based on the maximum spatial correlation tracking technique (MASCOTTE). J. Appl. Meteor., 40, 16831701, https://doi.org/10.1175/1520-0450(2001)040<1683:ASMTIS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, Y.-L., X. A. Chen, and Y.-X. Zhang, 1994: A diagnostic study of the low-level jet during TAMEX IOP 5. Mon. Wea. Rev., 122, 22572284, https://doi.org/10.1175/1520-0493(1994)122<2257:ADSOTL>2.0.CO;2.

    • 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
  • Du, Y., Q. Zhang, Y. Ying, and Y. Yang, 2012: Characteristics of low-level jets in Shanghai during the 2008–2009 warm seasons as inferred from wind profiler radar data. J. Meteor. Soc. Japan, 90, 891903, https://doi.org/10.2151/jmsj.2012-603.

    • 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
  • Garreaud, R. D., and J. M. Wallace, 1998: Summertime incursions of midlatitude air into subtropical and tropical South America. Mon. Wea. Rev., 126, 27132733, https://doi.org/10.1175/1520-0493(1998)126<2713:SIOMAI>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hersbach, H., and Coauthors, 2020: The ERA5 global reanalysis. Quart. J. Roy. Meteor. Soc., 146, 19992049, https://doi.org/10.1002/qj.3803.

  • Hoecker, W., 1963: Three southerly low-level jet systems de- lineated 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
  • Houze, R. A., K. L. Rasmussen, M. D. Zuluaga, and S. R. Brodzik, 2015: The variable nature of convection in the tropics and subtropics: A legacy of 16 years of the tropical rainfall measuring mission satellite. Rev. Geophys., 53, 9941021, https://doi.org/10.1002/2015RG000488.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Liu, C., and E. J. Zipser, 2015: The global distribution of largest, deepest, and most intense precipitation systems. Geophys. Res. Lett., 42, 35913595, https://doi.org/10.1002/2015GL063776.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 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
  • Martinez, J. A., and F. Dominguez, 2014: Sources of atmospheric moisture for the La Plata River basin. J. Climate, 27, 67376753, https://doi.org/10.1175/JCLI-D-14-00022.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Matsudo, C. M., and P. V. Salio, 2011: Severe weather reports and proximity to deep convection over Northern Argentina. Atmos. Res., 100, 523537, https://doi.org/10.1016/j.atmosres.2010.11.004.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mezher, R. N., M. Doyle, and V. Barros, 2012: Climatology of hail in Argentina. Atmos. Res., 114–115, 7082, https://doi.org/10.1016/j.atmosres.2012.05.020.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Montini, T. L., C. Jones, and L. M. V. Carvalho, 2019: The South American low-level jet: A new climatology, variability, and changes. J. Geophys. Res. Atmos., 124, 12001218, https://doi.org/10.1029/2018JD029634.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mulholland, J. P., S. W. Nesbitt, R. J. Trapp, K. L. Rasmussen, and P. V. Salio, 2018: Convective storm life cycle and environments near the Sierras de Córdoba, Argentina. Mon. Wea. Rev., 146, 25412557, https://doi.org/10.1175/MWR-D-18-0081.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nascimento, M. G., D. L. Herdies, and D. O. De 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
  • Nesbitt, S. W., R. Cifelli, and S. A. Rutledge, 2006: Storm morphology and rainfall characteristics of TRMM precipitation features. Mon. Wea. Rev., 134, 27022721, https://doi.org/10.1175/MWR3200.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nesbitt, S. W., and Coauthors, 2021: A storm safari in subtropical South America: Proyecto RELAMPAGO. Bull. Amer. Meteor. Soc., 102, E1621E1644, https://doi.org/10.1175/BAMS-D-20-0029.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nicolini, M., and A. C. Saulo, 2000: ETA characterization of the 1997–1998 warm season Chaco jet cases. Preprints, Sixth Int. Conf. on Southern Hemisphere Meteorology and Oceanography, Santiago, Chile, Amer. Meteor. Soc., 330331.

    • Search Google Scholar
    • Export Citation
  • Nicolini, M., and A. C. Saulo, 2006: Modeled Chaco low-level jets and related precipitation patterns during the 1997–1998 warm season. Meteor. Atmos. Phys., 94, 129143, https://doi.org/10.1007/s00703-006-0186-7.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nicolini, M., P. Salio, G. Ulke, J. Marengo, M. Douglas, J. Paegle, and E. Zipser, 2004a: South American low-level jet diurnal cycle and three dimensional structure. CLIVAR Exchanges, No. 9, International CLIVAR Project Office, Southampton, United Kingdom, 68.

  • Nicolini, M., P. Salio, and J. Paegle, 2004b: Diurnal wind cycle of the South American low-level jet. First Int. CLIVAR Science Conf. Poster Session 2: Monsoon Systems, Baltimore, MD, WCRP, MS-80.

    • Search Google Scholar
    • Export Citation
  • Nogués-Paegle, J., and K. C. Mo, 1997: Alternating wet and dry conditions over South America during summer. Mon. Wea. Rev., 125, 279291, https://doi.org/10.1175/1520-0493(1997)125<0279:AWADCO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Oliveira, M. I., E. L. Nascimento, and C. Kannenberg, 2018: A new look at the identification of low-level jets in South America. Mon. Wea. Rev., 146, 23152334, https://doi.org/10.1175/MWR-D-17-0237.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Paegle, J., 1998: A comparative review of South American low level jets. Meteorologica, 23, 7381.

  • Piersante, J. O., K. L. Rasmussen, R. S. Schumacher, A. K. Rowe, and L. A. McMurdie, 2021: A synoptic evolution comparison of the smallest and largest MCSs in subtropical South America between spring and summer. Mon. Wea. Rev., 149, 19431966, https://doi.org/10.1175/MWR-D-20-0208.1.

    • Search Google Scholar
    • Export Citation
  • Rasmussen, K. L., and R. A. Houze, 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, 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, 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
  • Rasmussen, K. L., M. M. Chaplin, M. D. Zuluaga, and R. A. Houze, 2016: Contribution of extreme convective storms to rainfall in South America. J. Hydrometeor., 17, 353367, https://doi.org/10.1175/JHM-D-15-0067.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rasmusson, E. M., and K. C. Mo, 1996: Large-scale atmospheric moisture cycling as evaluated from NMC global analysis and forecast products. J. Climate, 9, 32763297, https://doi.org/10.1175/1520-0442(1996)009<3276:LSAMCA>2.0.CO;2.

    • 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. Monaghan, 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, 2010: Extreme summer convection in South America. J. Climate, 23, 37613791, https://doi.org/10.1175/2010JCLI3465.1.

    • 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.

    • 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. 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
  • Servicio Meteorológico Nacional—Argentina, 2019: SMN radiosonde data, version 1.0. Accessed 26 September 2019, https://doi.org/10.26023/E8MP-0GD3-4903.

    • 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
  • Silvers, L. G., and W. H. Schubert, 2012: A theory of topographically bound balanced motions and application to atmospheric low-level jets. J. Atmos. Sci., 69, 28782891, https://doi.org/10.1175/JAS-D-11-0309.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Stein, A. F., R. R. Draxler, G. D. Rolph, B. J. B. Stunder, M. D. Cohen, and F. Ngan, 2015: NOAA’s hysplit atmospheric transport and dispersion modeling system. Bull. Amer. Meteor. Soc., 96, 20592077, https://doi.org/10.1175/BAMS-D-14-00110.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 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
  • UCAR/NCAR–Earth Observing Laboratory, 2020: Multi-network composite highest resolution radiosonde data, version 1.3. Accessed 26 September 2019, https://doi.org/10.26023/GKFF-YNBJ-BV14.〉

    • 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
  • Velasco, I. Y., and J. M. Fritsch, 1987: Mesoscale convective complexes in the Americas. J. Geophys. Res., 92, 95919613, https://doi.org/10.1029/JD092iD08p09591.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vera, C., and Coauthors, 2006: The South American low-level jet experiment. Bull. Amer. Meteor. Soc., 87, 6378, https://doi.org/10.1175/BAMS-87-1-63.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vila, D. A., L. A. T. Machado, H. Laurent, and I. Velasco, 2008: Forecast and tracking the evolution of cloud clusters (ForTraCC) using satellite infrared imagery: Methodology and validation. Wea. Forecasting, 23, 233245, https://doi.org/10.1175/2007WAF2006121.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Walters, C. K., J. A. Winkler, S. Husseini, R. Keeling, J. Nikolic, and S. Zhong, 2014: Low-level jets in the North American Regional Reanalysis (NARR): A comparison with rawinsonde observations. J. Appl. Meteor. Climatol., 53, 20932113, https://doi.org/10.1175/JAMC-D-13-0364.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zipser, E. J., D. J. Cecil, C. Liu, S. W. Nesbitt, and D. P. Yorty, 2006: Where are the most intense thunderstorms on Earth? Bull. Amer. Meteor. Soc., 87, 10571071, https://doi.org/10.1175/BAMS-87-8-1057.

    • Crossref
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 288 275 22
Full Text Views 100 97 12
PDF Downloads 102 96 16

New Insights into the South American Low-Level Jet from RELAMPAGO Observations

View More View Less
  • 1 aDepartment of Atmospheric Sciences, University of Washington, Seattle, Washington
  • | 2 bDepartment of Atmospheric and Oceanic Sciences, University of Wisconsin–Madison, Madison, Wisconsin
  • | 3 cDepartment of Atmospheric Science, Colorado State University, Fort Collins, Colorado
Restricted access

Abstract

The Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) campaign produced unparalleled observations of the South American low-level jet (SALLJ) in central Argentina with high temporal observations located in the path of the jet and upstream of rapidly growing convection. The vertical and temporal structure of the jet is characterized using 3-hourly soundings launched at two fixed sites near the Sierras de Córdoba (SDC), along with high-resolution reanalysis data. Objective SALLJ identification criteria are applied to each sounding to determine the presence, timing, and vertical characteristics of the jet. The observations largely confirm prior results showing that SALLJs most frequently come from the north, occur overnight, and peak in the low levels, though SALLJs notably peaked higher near the end of longer-duration events during RELAMPAGO. This study categorizes SALLJs into shorter-duration events with jet cores peaking overnight in the low levels and longer 5–6-day events with elevated jets near the end of the period that lack a clear diurnal cycle. Evidence of both boundary layer processes and large-scale forcing were observed during shorter-duration events, whereas synoptic forcing dominated the longer 5–6-day events. The highest amounts of moisture and larger convective coverage east of the SDC occurred near the end of the 5–6-day SALLJ events.

Significance Statement

The South American low-level jet (SALLJ) is an area of enhanced northerly winds that likely contributes to long-lived, widespread thunderstorms in Southeastern South America (SESA). This study uses observations from a recent SESA field project to improve understanding of the variability of the SALLJ and the underlying processes. We related jet occurrence to upper-level environmental patterns and differences in the progression speed of those patterns to varying durations of the jet. Longer-duration jets were more elevated, transported moisture southward from the Amazon, and coincided with the most widespread storms. These findings enable future research to study the role of the SALLJ in the life cycle of storms in detail, leading to improved storm prediction in SESA.

© 2022 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

This article is included in the RELAMPAGO-CACTI Special Collection.

Corresponding author: Clayton R. S. Sasaki, crs236@uw.edu

Abstract

The Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) campaign produced unparalleled observations of the South American low-level jet (SALLJ) in central Argentina with high temporal observations located in the path of the jet and upstream of rapidly growing convection. The vertical and temporal structure of the jet is characterized using 3-hourly soundings launched at two fixed sites near the Sierras de Córdoba (SDC), along with high-resolution reanalysis data. Objective SALLJ identification criteria are applied to each sounding to determine the presence, timing, and vertical characteristics of the jet. The observations largely confirm prior results showing that SALLJs most frequently come from the north, occur overnight, and peak in the low levels, though SALLJs notably peaked higher near the end of longer-duration events during RELAMPAGO. This study categorizes SALLJs into shorter-duration events with jet cores peaking overnight in the low levels and longer 5–6-day events with elevated jets near the end of the period that lack a clear diurnal cycle. Evidence of both boundary layer processes and large-scale forcing were observed during shorter-duration events, whereas synoptic forcing dominated the longer 5–6-day events. The highest amounts of moisture and larger convective coverage east of the SDC occurred near the end of the 5–6-day SALLJ events.

Significance Statement

The South American low-level jet (SALLJ) is an area of enhanced northerly winds that likely contributes to long-lived, widespread thunderstorms in Southeastern South America (SESA). This study uses observations from a recent SESA field project to improve understanding of the variability of the SALLJ and the underlying processes. We related jet occurrence to upper-level environmental patterns and differences in the progression speed of those patterns to varying durations of the jet. Longer-duration jets were more elevated, transported moisture southward from the Amazon, and coincided with the most widespread storms. These findings enable future research to study the role of the SALLJ in the life cycle of storms in detail, leading to improved storm prediction in SESA.

© 2022 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

This article is included in the RELAMPAGO-CACTI Special Collection.

Corresponding author: Clayton R. S. Sasaki, crs236@uw.edu
Save