Start Submission Become a Reviewer

Reading: On precursors of South American cyclogenesis

Download

A- A+
Alt. Display

Original Research Papers

On precursors of South American cyclogenesis

Authors:

David Mendes ,

Centro de Geofísica da Universidade de Lisboa, Faculdade de ciências, Departamento de Física, Campo Grande, Ed. C8, Piso 6, 1749-016 Lisboa, PT
X close

Enio P. Souza,

Federal University of Campina Grande, Department of Atmospheric Sciences, Campina Grande, BR
X close

Isabel F. Trigo,

Meteorology Institute of Portugal, University of Lisboa, CGUL, IDL, Lisboa, PT
X close

Pedro M. A. Miranda

University of Lisbon, CGUL, IDL, Lisboa, PT
X close

Abstract

Cyclogenesis over the southern region of South America is studied in relation to the evolution of dynamic and thermodynamic fields over the continent, using storm tracking and derived composite analysis over a 25 yr period. Results show that, irrespective of the season, there is always a moist-entropy reservoir northwest of the cyclone formation region. One day before cyclone formation, moist entropy over North Argentina is anomalously high and increasing, due to an intensification of the northerly flow along the eastern flank of the Andes, peaking at the time of cyclogenesis. The new cyclone is fed by warm and moist air coming from the continent but, as it intensifies and moves eastwards, imposes an anomalously southerly flow reducing the moist-entropy anomaly over South America. The presence of the Andes Cordillera plays a major role controlling the location of the main cyclone formation area in the region by (i) channelling the warm moist northerly flow in the lower troposphere and (ii) inducing cyclonic circulation in the lee side, when upper troughs travelling eastwards move over the mountain range at the middle latitudes.

How to Cite: Mendes, D., Souza, E.P., Trigo, I.F. and Miranda, P.M.A., 2007. On precursors of South American cyclogenesis. Tellus A: Dynamic Meteorology and Oceanography, 59(1), pp.114–121. DOI: http://doi.org/10.1111/j.1600-0870.2006.00215.x
  Published on 01 Jan 2007
 Accepted on 5 Oct 2006            Submitted on 28 Oct 2005

References

  1. Bolton , D. 1980 . The computation of equivalent potential temperature. Mon. Wea. Re v . 7 , 1046 – 1053 .  

  2. Dal-Piva , E. 2001 . Estudo de caso sobre o papel dos fluxos de calor latente e sensivel em superficie em processo de ciclogenese da costa leste ocorrido na costa leste da America do Sul. Master Thesis (in Portuguese), INPE-8498-DTI/781,162pp.  

  3. Emanuel , K. A. 1989 . The finite-amplitude nature of tropical cyclogenesis. J. Atmos. Sc i . 46 , 3431 – 3456 .  

  4. Frederiksen , J. S. 1985 . The geographical locations of Southern Hemisphere storm tracks: linear theory. J. Atmos. Sc i . 42 , 710 – 723 .  

  5. Gan , M. A. and Rao , V. B. 1991 . Surface cyclogenesis over South America. Mon. Wea. Re v . 119 , 1293 – 1302 .  

  6. Garreaud , R. D. and Wallace , J. M. 1998 . Summertime incursions of midlatitude air into subtropical and tropical South America. Mon. Wea. Re v . 10 , 2713 – 2733 .  

  7. James , I. N. and Anderson , D. L. T. 1984 . The seasonal mean flow and distribution of large-scale weather systems in the southern hemisphere: the effects of moisture transports . Quart. J. R. Met. Soc . 110 , 943 – 966 .  

  8. Kalnay , E. , Kanamitsu , M. , Kistler , R. , Collins , W. , Deaven ; D. and co-authors 1996 . NCEP/NCAR 40-year reanalysis project. Bull. Am. Meteorol. Soc . 77 , 437 - 471 .  

  9. Marengo , J. A. , Soares , W. R. , Saulo , C. and Nicolini , M. 2004 . Climatology of the low-level jet east of the Andes as derived from the NCEP reanalyses . J. Climate 17 , 2261 – 2280 .  

  10. Peixoto , J. P. and Oort , A. H. 1992 . Physics of Climate . American Institute of Physics , New York , 520 pp .  

  11. Possia , N. 2002 . An explosive cyclogenesis over land . Atmosféra 15 , 1 – 19 .  

  12. Rennó , N. O. and Ingersoll , A. P. 1996 . Natural convection as a heat engine: a theory for CAPE. J. Atmos. Sc i . 53 , 572 – 585 .  

  13. Satyamurty , P. , Nobre , C. A. and Silva Dias , P. L. 1998 . Meteorology of the tropics. South America, pp 119-139, in Meteorology of the Southern Hemisphere. (eds D. K. Karoly and D. G. Vmcent ). Meteorological Monographs, 49, American Meteorological Society’, Boston.  

  14. Seluchi , M. E. 1995 . Diagnostico y pronostico de situaciones sinópticas conducentes a cyclogenesis sobre el este de Sudamerica . Geofisica Internacional 34 , 171 – 186 .  

  15. Seluchi , M. E. , and A. C. Saulo 1998 . Possible mechanisms yielding an explosive coastal cyclogenesis over South America: experiments using a limited area model . Aust. Meteor. Mag . 47 , 309 – 320 .  

  16. Sinclair , M. E 1995 . A climatology of cyclogenesis for the Southern Hemisphere. Mon. Wea. Re v . 123 , 1601 – 1619 .  

  17. Simmonds , I. and Keay , K. 2000 . Mean southern hemisphere extrat-ropical cyclone behavior in the 40-year NCEP-NCAR reanalysis. .1 . Climate 13 , 873 – 885 .  

  18. Trigo I. E , Davies , T. D. and Bigg , G. R. 1999 . Objective climatology of cyclones in the Mediterranean region , J. Climate 12 , 1685 – 1696 .  

  19. Trigo , I. E 2005 . Climatology and interannual variability of storm-tracks in the Euro-Atlantic sector: a comparison between ERA-40 and NCEP/NCAR reanalyses, Clim. Dyn. , DOI https://doi.org/10.1007/s00382-005-0065-9 .  

  20. Velasco , I. and Fritsch , M. 1987 . Mesoscale convective complexes in Americas . J. Geophys. Res . 92 , 9591 – 9613 .  

  21. Wilks , D., 1995 . Statistical Methods in the Atmospheric Sciences . An Introduction. Academic Press , San Diego , 467pp .  

comments powered by Disqus