Climate Dynamics

, Volume 53, Issue 3–4, pp 1393–1411 | Cite as

Climatology of easterly wave disturbances over the tropical South Atlantic

  • Helber B. GomesEmail author
  • Tércio Ambrizzi
  • Bruce F. Pontes da Silva
  • Kevin Hodges
  • Pedro L. Silva Dias
  • Dirceu L. Herdies
  • Maria Cristina L. Silva
  • Heliofábio B. Gomes


A 21-year climatology of Easterly Waves Disturbances (EWDs) over the tropical South Atlantic (TSA) has been examined using data from the European Centers for Medium-Range Weather Forecasting interim reanalysis (ERAI) and satellite data. This includes the frequency distribution of EWDs and their interannual variability. The large-scale environment associated with EWDs has been investigated for the coastal region of Northeast Brazil (NEB) for the rainy (April–August) season using a composite analysis. EWDs were first identified in ERAI, resulting in 518 observed cases. These were found to show notable interannual variability with around 16–40 episodes each year and with an average lifetime of 4–6 days. Of the identified EWDs, 97% reached the coast of NEB, of which 64% were convective in nature and 14% moved across the NEB region and reached the Amazon. The annual occurrence of EWDs seems to be lower (higher) during El Niño (La Niña). The monthly occurrence of EWDs shows higher activity in the rainy season. EWDs originate in association with four types of system: cold fronts, convective clusters from the west coast of Africa, Intertropical Convergence Zone and Tropical Upper Tropospheric Cyclonic Vortices. The composite analysis indicates strong relative vorticity and divergence anomalies at low levels, as well as in the vertical profiles of relative humidity and vertical velocity (omega). The precipitation composites show that the EWDs propagate between the TSA and NEB and contribute at least 60% of the total rainfall over the east coast of NEB throughout the rainy season.


Easterly waves disturbances Tropical South Atlantic Northeast Brazil and climatology 



This study was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPq (Grant nos. 143207/2009-1, 304298/2014-0 and 405664/2018-4) and Fundação de Amparo à Pesquisa do Estado de São Paulo, FAPESP, Brazil (Grant no. 08/58101-9). Pedro L. Silva Dias acknowledges the CNPq support through Grant no. 309395/2013-5. TA was also supported by the National Institute of Science and Technology for Climate Change Phase 2 under CNPq Grant 465501/2014-1, FAPESP Grant 2014/50848-9, and the National Coordination for High Level Education and Training (CAPES) Grant 16/2014. We thank the two reviewers for their very helpful comments which encouraged us to improve the analysis and present a comparison between subjective and objective tracking.


  1. Asnani GC (1993) Tropical meteorology. Published by GC Asnani, Pune, India, p 1202Google Scholar
  2. Berry G, Thorncroft C (2007) African easterly waves during 2004—analysis using objective techniques. Mon Weather Rev 135:1251–1267CrossRefGoogle Scholar
  3. Berry FA, Bollay, Norman E, Beers R (1945) Handbook of meteorology. McGraw-Hill Book Company, LondonGoogle Scholar
  4. Burpee RW (1972) The origin and structure of easterly waves in the lower troposphere of North African. J Atmos Sci 29:77–90CrossRefGoogle Scholar
  5. Burpee RW (1974) Characteristics of north African easterly waves during the summers of 1968 and 1969. J Atmos Sci 31(6):1556–1570CrossRefGoogle Scholar
  6. Burpee RW (1975) Some features of synoptic-scale waves based on compositing analysis of GATE data. Mon Weather Rev 103:921–925CrossRefGoogle Scholar
  7. Caetano JMV (2011) Analysis of easterly waves on the east coast of northeastern Brazil for the period between 1999 and 2009. Master Dissertation, Federal University of Rio de Janeiro (in Portuguese) Google Scholar
  8. Carlson TN (1969) Some remarks on African disturbances and their progress over the tropical Atlantic. Mon Weather Rev 97:716–726CrossRefGoogle Scholar
  9. Chan CS (1990) Analysis of easterly wave disturbances over the south equatorial Atlantic Ocean. Master Dissertation, National Institute of Space Research (in Portuguese) Google Scholar
  10. Cotton WR (1982) Modification of precipitation from warm clouds—a review. Bull Am Meteorol Soc 63:146–160CrossRefGoogle Scholar
  11. Coutinho EC (1999) Study of the atmospheric characteristics at the region of Alcântara Launching Center - MA. Master Dissertation, National Institute of Space Research (in Portuguese)Google Scholar
  12. Coutinho EC, Fisch G (2007) Easterly wave disturbances (EWDs) at the region of Alcântara Launching Center—MA. Braz J Meteorol 22(2):193–203 (in Portuguese) CrossRefGoogle Scholar
  13. Dee DP et al (2011) The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Q J R Meteorol Soc 137:553–597. CrossRefGoogle Scholar
  14. Diedhiou AS, Machado LAT, Laurent H (2010) Mean kinematic characteristics of synoptic easterly disturbances over the. Atlantic Adv Atmos Sci 27(3):1–17Google Scholar
  15. Fedorova N (2008b) Synoptic IV: systems and processes synoptic over South America. Federal University of Alagoas, Maceió (in Portuguese) Google Scholar
  16. Gomes HB, Ambrizzi T, Herdies DL, Hodges K, Pontes da Silva BF (2015) Easterly wave disturbances over northeast Brazil: an observational analysis. Adv Meteorol. Google Scholar
  17. Hall BA (1989) Westward—moving disturbances in the south Atlantic coinciding with heavy rainfall events at Ascension Island. Meteorol Mag 118:175–181Google Scholar
  18. Hodges KI (1995) Feature tracking on the unit sphere. Mon Weather Rev 123:3458–3465CrossRefGoogle Scholar
  19. Hodges KI (1999) Adaptive constraints for feature tracking. Mon Weather Rev 127:1362–1373CrossRefGoogle Scholar
  20. Huffman GJ et al (2001) Global precipitation at one-degree daily resolution from multisatellite observations. J Hydrometeorol 2:36–50CrossRefGoogle Scholar
  21. Kayano MT (1979) A climatic and synoptic study using radiosonde data (1968–1976) from Manaus and Belem. Master Dissertation, National Institute for Space Research (in Portuguese)Google Scholar
  22. Kayano MT (2003) Low-level high-frequency modes in the tropical Atlantic and their relation to precipitation in the equatorial South America. Meteorol Atmos Phys 83:263–276Google Scholar
  23. Kousky VE (1979) Frontal influences on northeast Brazil. Mon Weather Rev 107:1140–1153CrossRefGoogle Scholar
  24. Kousky VE (1980) Diurnal rainfall variation in northeast Brazil. Mon Weather Rev 108:488–498CrossRefGoogle Scholar
  25. Krishnamurti TN (1978) Tropical meteorology. WMO Publ. No. 364, Compendium of MeteorologyGoogle Scholar
  26. Liebman B, Smith CA (1996) Description of a complete (interpolated) outgoing longwave radiation dataset. Bull Am Meteorol Soc 77:1275–1277Google Scholar
  27. Liu C, Zipser EJ (2009) “Warm Rain” in the tropics: seasonal and regional distributions based on 9 year of TRMM Data. J Clim 22:767–779CrossRefGoogle Scholar
  28. Lucena DB, Servain J, Gomes Filho MF (2011) Rainfall response in northeast Brazil from ocean climate variability during the secondy half of the twentieth century. J Clim 24:6174–6184CrossRefGoogle Scholar
  29. Merritt NS (1964) Easterly waves and perturbations, a reappraisal. J Appl Meteorol 3:367–382CrossRefGoogle Scholar
  30. Molion LCB, Bernardo SO (2002) A review of rainfall dynamics over northeastern Brazil. Braz J Meteorol Revista Brasileira de Meteorologia 17(1):2–10 (in Portuguese)Google Scholar
  31. Motas GV (1997) Observational study of easterly wave disturbances over the northeastern Brazil. Master Dissertation, University of São Paulo (in Portuguese)Google Scholar
  32. Neiva EJF (1975) An investigations of wave-type disturbances over the tropical South Atlantic Ocean. M.Sc. Thesis, Naval Post Graduate SchoolGoogle Scholar
  33. Pezzi LP, Calvalcanti IFA (2001) The relative importance of ENSO and tropical Atlantic sea surface temperature anomalies for seasonal precipitation over South America: a numerical study. Clim Dyn 17:205–212CrossRefGoogle Scholar
  34. Pontes da Silva BF (2011) Easterly Waves contribution for the eastern northeast Brazil precipitation: mean synoptic evolution and numerical simulations. Master Dissertation, University of São Paulo (in Portuguese) Google Scholar
  35. Rao VB, Lima M, Franchito SH (1993) Seasonal and interannual variations of rainfall over eastern northeast Brazil. J Clim 6:1754–1763CrossRefGoogle Scholar
  36. Raupp CFM, Silva Dias PL (2005) Excitation mechanism of mixed Rossby—gravity waves in the equatorial atmosphere: role of the nonlinear interactions among equatorial waves. J Atmos Sci 62(5):1446–1462CrossRefGoogle Scholar
  37. Reed JR, Norquist DC, Recker EE (1977) The structure and properties of African wave disturbances as observed during phase III of GATE. Mon Weather Rev 105:317–333CrossRefGoogle Scholar
  38. Riehl H (1945) Tropical meteorology. McGgraw-Hill, New YorkGoogle Scholar
  39. Santos IA, Silva Dias PL, Torres AR (2002) The role of mixed Rossby-gravity waves on the organization of convection in the Amazon. Preprints, 12th Brazilian Congress of Meteorology, Foz do Iguaçu, Brazil, Brazilian Society of Meteorology, pp 3995–4001Google Scholar
  40. Santos e Silva CM, Silva A, Oliveira P, Lima KC (2014) Dynamical downscaling of the precipitation in northeast Brazil with a regional climate model during contrasting years. Atmos Sci Let 15:50–57CrossRefGoogle Scholar
  41. Schlueter A, Fink A, Knippertz P, Vogel P (2018) A systematic comparison of tropical waves over northern Africa. Part I: influence on rainfall. J Clim. (in press) Google Scholar
  42. Serra YL, Kiladis GN, Cronin MG (2008) Horizontal and vertical structure of easterly waves in the Pacific ITCZ. J Atmos Sci 65:1266–1284CrossRefGoogle Scholar
  43. Serra YL, Kiladis GN, Hodges KI (2010) Tracking and mean structure of easterly waves over the intra-Americas sea. J Clim 23:4823–4840CrossRefGoogle Scholar
  44. Simmons A, Uppala S, Dee DP (2007a) Update on ERA-interim. ECMWF Newsl 111:5Google Scholar
  45. Simmons A, Uppala S, Dee DP, Kobayashi S (2007b) ERA-interim: new ECMWF reanalysis products from 1989 onwards. ECMWF Newsl 110:25–35Google Scholar
  46. Thorncroft CD (1995) An idealized study of African easterly waves. Part III: more realistic basic states. Q J R Meteorol Soc 121:1589–1614CrossRefGoogle Scholar
  47. Thorncroft CD, Hodges KI (2001) African easterly wave variability and its relationship to Atlantic tropical cyclone activity. J Clim 14:1166–1179CrossRefGoogle Scholar
  48. Torres RR (2008) Analysis and modeling of easterly waves disturbances over the East Coast of Northeast Brazil. Master Dissertation, National Institute for Space Research (in Portuguese)Google Scholar
  49. Torres RR, Ferreira NJ (2011) Case studies of easterly wave disturbances over northeast Brazil using the eta model. Weather Forecast 26:225–235CrossRefGoogle Scholar
  50. Uppala S et al (2008) Towards a climate data assimilation system: status update of ERA-Interim. ECMWF Newsl 115:12–18Google Scholar
  51. Yamazaki Y, Rao VB (1977) Tropical cloudiness over South Atlantic Ocean. J Meteorol Soc Jpn 55:205–207CrossRefGoogle Scholar
  52. Yang GY, Methven J, Woolnough S, Hodges K, Hoskins B (2018) Linking African easterly wave activity with equatorial waves and influence of Rossby waves from the South Hemisphere. J Atmos Sci 75(6):1783–1809CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Helber B. Gomes
    • 1
    Email author
  • Tércio Ambrizzi
    • 2
  • Bruce F. Pontes da Silva
    • 3
  • Kevin Hodges
    • 4
  • Pedro L. Silva Dias
    • 2
  • Dirceu L. Herdies
    • 5
  • Maria Cristina L. Silva
    • 1
  • Heliofábio B. Gomes
    • 1
  1. 1.Institute of Atmospheric SciencesFederal University of AlagoasMaceióBrazil
  2. 2.Department of Atmospheric SciencesUniversity of Sao PauloSão PauloBrazil
  3. 3.Capixaba Institute of ResearchTechnical Assistance and Rural ExtensionVitoriaBrazil
  4. 4.Department of MeteorologyUniversity of ReadingReadingUK
  5. 5.National Institute for Space ResearchCachoeira PaulistaBrazil

Personalised recommendations