Climate Dynamics

, Volume 43, Issue 5–6, pp 1557–1573 | Cite as

The self-organizing map, a new approach to apprehend the Madden–Julian Oscillation influence on the intraseasonal variability of rainfall in the southern African region

  • Pascal Oettli
  • Tomoki Tozuka
  • Takeshi Izumo
  • Francois A. Engelbrecht
  • Toshio Yamagata
Article
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Abstract

The Madden–Julian Oscillation (MJO) is the major mode of intraseasonal variability (30–60 days) in the tropics, having large rainfall impacts globally, and possibly on southern Africa. However, the latter impact is not well understood and needs to be further explored. The life cycle of the MJO, known to be asymmetric, has been nevertheless analyzed usually through methods constrained by both linearity and orthogonality, such as empirical orthogonal function analysis. Here we explore a non-linear classification method, the self-organizing map (SOM), a type of artificial neural network used to produce a low-dimensional representation of high-dimensional datasets, to capture more accurately the life cycle of the MJO and its global impacts. The classification is applied on intraseasonal anomalies of outgoing longwave radiation within the tropical region over the 1980–2009 period. Using the SOM to describe the MJO is a new approach, complimentary to the usual real-time multivariate MJO index. It efficiently captures this propagative phenomenon and its seasonality, and is shown to provide additional temporal and spatial information on MJO activity. For each node, the subtropical convection is analyzed, with a particular focus on the southern Africa region. Results show that the convection activity over the central tropical Indian Ocean is a key factor influencing the intraseasonal convective activity over the southern African region. Enhanced (suppressed) convection over the central Indian Ocean tends to suppress (enhance) convection over the southern African region with a 10-day lag by modulating the moisture transport.

Keywords

Intraseasonal variability Madden–Julian Oscillation Self-organizing map Subtropical atmosphere response Southern African rainfall 
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Notes

Acknowledgments

The present research is supported by the Japan Science and Technology Agency (JST)/Japan International Cooperation Agency (JICA) through the Science and Technology Research Partnership for Sustainable Development (SATREPS). NCEP/DOE 2 Reanalysis, Interpolated OLR and NOAA High Resolution SST data are provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd/. The SOM is performed using the SOM_PAK software (www.cis.hut.fi/research/som_pak). Other calculations, as well as graphics, are made using the R project for statistical computing (http://www.r-project.org). The authors would like to thank two anonymous reviewers for their helpful comments.

References

  1. Barlow M, Wheeler M, Lyon B, Cullen H (2005) Modulation of daily precipitation over southwest Asia by the Madden–Julian Oscillation. Mon Weather Rev 133:3579–3594CrossRefGoogle Scholar
  2. Bladé I, Hartmann DL (1995) The linear and nonlinear extratropical response of the atmosphere to tropical intraseasonal heating. J Atmos Sci 52:4448–4471CrossRefGoogle Scholar
  3. Bloomfield P (2004) Fourier analysis of time series: an introduction. Wiley, New YorkGoogle Scholar
  4. Bortel R, Sovka P (2007) Approximation of statistical distribution of magnitude squared coherence estimated with segment overlapping. Signal Process 87:1100–1117CrossRefGoogle Scholar
  5. Chattopadhyay R, Vintzileos A, Zhang C (2013) A description of the Madden–Julian Oscillation based on a self-organizing map. J Clim 26:1716–1732CrossRefGoogle Scholar
  6. Chelliah M, Arkin P (1992) Large-scale interannual variability of monthly outgoing longwave radiation anomalies over the global tropics. J Clim 5:371–389CrossRefGoogle Scholar
  7. Daniell PJ (1946) Discussion on the “Symposium on autocorrelation in time series”. J R Stat Soc Suppl 8:88–90Google Scholar
  8. Donald A, Meinke H, Power B, Maia AHN, Wheeler MC, White N, Stone RC, Ribbe J (2006) Near-global impact of the Madden–Julian Oscillation on rainfall. Geophys Res Lett. doi: 10.1029/2005GL025155
  9. Duchon CE (1979) Lanczos filtering in one and two dimensions. J Appl Meteorol 18:1016–1022CrossRefGoogle Scholar
  10. Dyer TGJ (1979) Rainfall along the east coast of southern Africa, the southern oscillation, and the latitude of the subtropical high pressure belt. Q J R Meteorol Soc 105:445–451CrossRefGoogle Scholar
  11. Ebisuzaki W (1997) A method to estimate the statistical significance of a correlation when the data are serially correlated. J Clim 10:2147–2153CrossRefGoogle Scholar
  12. Enochson LD, Goodman NR (1965) Gaussian approximations to the distribution of sample coherence. Air Force Flight Dynamics Laboratory, Wright-Patterson Air Force baseGoogle Scholar
  13. Fauchereau N, Pohl B, Reason CJC, Rouault M, Richard Y (2009) Recurrent daily OLR patterns in the Southern Africa/Southwest Indian Ocean region, implications for South African rainfall and teleconnections. Clim Dyn 32:575–591CrossRefGoogle Scholar
  14. Ferranti L, Palmer TN, Molteni F, Klinker E (1990) Tropical-extratropical interaction associated with the 30–60 day oscillation and its impact on medium and extended range prediction. J Atmos Sci 47:2177–2199CrossRefGoogle Scholar
  15. Goff JA, Gratch S (1946) Low-pressure properties of water from −160 to 212F. Trans Am Soc Heat Vent Eng 52:95–121Google Scholar
  16. Gutzler DS, Madden RA (1989) Seasonal variations in the spatial structure of intraseasonal tropical wind fluctuations. J Atmos Sci 46:641–660CrossRefGoogle Scholar
  17. Hart NCG, Reason CJC, Fauchereau N (2012a) Building a tropical-extratropical cloud band metbot. Mon Weather Rev 140:4005–4016CrossRefGoogle Scholar
  18. Hart NCG, Reason CJC, Fauchereau N (2012b) Cloud bands over souther Africa: seasonality, contribution to rainfall variability and modulation by the MJO. Clim Dyn. doi: 10.1007/s00382-012-1589-4
  19. Hayashi Y, Golder DG (1993) Tropical 40–50- and 25–30-day oscillations appearing in realistic and idealized GFDL climate models and the ECMWF dataset. J Atmos Sci 50:464–494CrossRefGoogle Scholar
  20. Hendon HH, Liebmann B (1990) The intraseasonal (30–50 day) oscillation of the Australian summer monsoon. J Atmos Sci 47:2909–2924CrossRefGoogle Scholar
  21. Hendon HH, Salby ML (1994) The life cycle of the Madden–Julian Oscillation. J Atmos Sci 51:2225–2237CrossRefGoogle Scholar
  22. Hewitson B, Crane RG (2002) Self-organizing maps: application to synoptic climatology. Clim Res 22:13–26CrossRefGoogle Scholar
  23. Jenkner J, Hsieh WW, Cannon AJ (2011) Seasonal modulations of the active MJO cycle characterized by nonlinear principal component analysis. Mon Weather Rev 139:2259–2275CrossRefGoogle Scholar
  24. Jones AG (1981) Transformed coherence functions for multivariate studies. IEEE Trans Acoust Speech Signal Process 29:317–319CrossRefGoogle Scholar
  25. Jones C (2000) Occurrence of extreme precipitation events in California and relationships with the Madden–Julian Oscillation. J Clim 13:3576–3587CrossRefGoogle Scholar
  26. Kanamitsu M, Ebisuzaki W, Woollen J, Yang SK, Hnilo JJ, Fiorino M, Potter GL (2002) NCEP-DOE AMIP-II reanalysis (R-2). Bull Am Meteorol Soc 83:1631–1643CrossRefGoogle Scholar
  27. Kessler WS (2001) EOF representations of the Madden–Julian Oscillation and its connection with ENSO. J Clim 14:3055–3061CrossRefGoogle Scholar
  28. Knutson TR, Weickmann KM (1987) 30–60 day atmospheric oscillations: composite life cycles of convection and circulation anomalies. Mon Weather Rev 115:1407–1436CrossRefGoogle Scholar
  29. Knutson TR, Weickmann KM, Kutzbach JE (1986) Global-scale intraseasonal oscillations of outgoing longwave radiation and 250 mb zonal wind during northern hemisphere summer. Mon Weather Rev 114:605–623CrossRefGoogle Scholar
  30. Kohonen T (1982) Self-organized formation of topologically correct feature maps. Biol Cybern 43:59–69CrossRefGoogle Scholar
  31. Kohonen T (1989) Self-organization and associative memory. Springer, BerlinCrossRefGoogle Scholar
  32. Kohonen T (2001) Self-organizing maps, 3rd edn. Springer, BerlinCrossRefGoogle Scholar
  33. Kohonen T, Hynninen J, Kangas J, Laaksonen J (1995) SOM_PAK: the self-organizing map program package. Helsinki University of Technology, Laboratory of Computer and Information Science, Espoo, Finland. http://www.cis.hut.fi/research/som_lvq_pak.shtml
  34. Lau K, Chan PH (1985) Aspects of the 40–50 day oscillation during the Northern winter as inferred from outgoing longwave radiation. Mon Weather Rev 113:1889–1909CrossRefGoogle Scholar
  35. Lawrence DM, Webster PJ (2002) The boreal summer intraseasonal oscillation: relationship between northward and eastward movement of convection. J Atmos Sci 59:1593–1606CrossRefGoogle Scholar
  36. Leloup J, Lachkar Z, Boulanger J, Thiria S (2007) Detecting decadal changes in ENSO using neural networks. Clim Dyn 28:147–162CrossRefGoogle Scholar
  37. Levey KM, Jury MR (1996) Composite intraseasonal oscillations of convection over Southern Africa. J Clim 9:1910–1920CrossRefGoogle Scholar
  38. Liebmann B, Smith CA (1996) Description of a complete (interpolated) outgoing longwave radiation dataset. Bull Am Meteorol Soc 77:1275–1277Google Scholar
  39. Liebmann B, Kiladis GN, Vera CS, Saulo AC, Carvalho LMV (2004) Subseasonal variations of rainfall in South America in the vicinity of the low-level jet east of the Andes and comparison to those in the South Atlantic convergence zone. J Clim 17:3829–3842CrossRefGoogle Scholar
  40. Lindesay JA (1988) South African rainfall, the Southern Oscillation and a Southern Hemisphere semi-annual cycle. J Climatol 8:17–30CrossRefGoogle Scholar
  41. Lindesay JA, Vogel CH (1990) Historical evidence for southern Oscillation—southern African rainfall relationships. Int J Climatol 10:679–689CrossRefGoogle Scholar
  42. Liu Y, Weisberg RH, Mooers CNK (2006) Performance evaluation of the self-organizing map for feature extraction. J Geophys Res. doi: 10.1029/2005JC003117
  43. Lyon B, Mason SJ (2007) The 1997–98 summer rainfall season in Southern Africa. Part I: observations. J Clim 20:5134–5148CrossRefGoogle Scholar
  44. Madden RA (1986) Seasonal variations of the 40–50 day oscillation in the tropics. J Atmos Sci 43:3138–3158CrossRefGoogle Scholar
  45. Madden RA, Julian PR (1971) Detection of a 40–50 day oscillation in the zonal wind in the tropical Pacific. J Atmos Sci 28:702–708CrossRefGoogle Scholar
  46. Madden RA, Julian PR (1972) Description of global-scale circulation cells in the tropics with a 40–50 day period. J Atmos Sci 29:1109–1123CrossRefGoogle Scholar
  47. Madden RA, Julian PR (1994) Observations of the 40–50-day tropical oscillation—a review. Mon Weather Rev 122:814–837CrossRefGoogle Scholar
  48. Maloney ED, Hartmann DL (1998) Frictional moisture convergence in a composite life cycle of the Madden–Julian Oscillation. J Clim 11:2387–2403CrossRefGoogle Scholar
  49. Marple SL (1986) Digital spectral analysis: with applications. Prentice-Hall Inc., New-JerseyGoogle Scholar
  50. Matthews AJ (2000) Propagation mechanisms for the Madden–Julian Oscillation. Q J R Meteorol Soc 126:2637–2651CrossRefGoogle Scholar
  51. Matthews AJ (2004) Intraseasonal variability over tropical Africa during northern summer. J Clim 17:2427–2440CrossRefGoogle Scholar
  52. Matthews AJ, Hoskins BJ, Masutani M (2004) The global response to tropical heating in the Madden–Julian Oscillation during the northern winter. Q J R Meteorol Soc 130:1991–2011CrossRefGoogle Scholar
  53. McGee OS (1970) Wind and humidity conditions over Durban during 1967. S Afr Geogr J 52:44–57CrossRefGoogle Scholar
  54. Mo KC, Higgins RW (1998) The Pacific-south American modes and tropical convection during the southern hemisphere winter. Mon Weather Rev 126:1581–1596CrossRefGoogle Scholar
  55. Morioka Y, Tozuka T, Yamagata T (2010) Climate variability in the southern Indian Ocean as revealed by self-organizing maps. Clim Dyn 35:1075–1088Google Scholar
  56. Mpeta EJ, Jury MR (2001) Intra-seasonal convective structure and evolution over tropical East Africa. Clim Res 17:83–92CrossRefGoogle Scholar
  57. Mutai CC, Ward MN (1998) Predictability of the East African short rains on intraseasonal to interannual timescales. In: Proceedings of 23rd annual climate diagnostics workshop. Miami, Florida, pp 23–46Google Scholar
  58. Percival DB, Walden AT (1993) Spectral analysis for physical applications. Cambridge University Press, CambridgeCrossRefGoogle Scholar
  59. Pohl B, Camberlin P (2006) Influence of the Madden–Julian Oscillation on East African rainfall. I: intraseasonal variability and regional dependency. Q J R Meteorol Soc 132:2521–2539CrossRefGoogle Scholar
  60. Pohl B, Richard Y, Fauchereau N (2007) Influence of the Madden–Julian Oscillation on southern African summer rainfall. J Clim 20:4227–4242CrossRefGoogle Scholar
  61. Pohl B, Fauchereau N, Richard Y, Rouault M, Reason CJC (2009) Interactions between synoptic, intraseasonal and interannual convective variability over southern Africa. Clim Dyn 33:1033–1050CrossRefGoogle Scholar
  62. Ratna S, Behera S, Ratnam JV, Takahashi K, Yamagata T (2012) An index for tropical temperate troughs over southern Africa. Clim Dyn. doi: 10.1007/s00382-012-1540-8
  63. Reynolds RW, Smith TM, Liu C, Chelton DB, Casey KS, Schlax MG (2007) Daily high-resolution-blended analyses for sea surface temperature. J Clim 20:5473–5496CrossRefGoogle Scholar
  64. Richard Y, Trzaska S, Roucou P, Rouault M (2000) Modification of the southern African rainfall variability/ENSO relationship since the late 1960s. Clim Dyn 16:883–895CrossRefGoogle Scholar
  65. Sakai K, Kawamura R, Iseri Y (2010) ENSO-induced tropical convection over the Indian and western Pacific oceans during the northern winter as revealed by a self-organizing map. J Geophys Res. doi: 10.1029/2010JD014415
  66. Salby ML, Hendon HH (1994) Intraseasonal behavior of clouds, temperature, and motion in the tropics. J Atmos Sci 51:2207–2224CrossRefGoogle Scholar
  67. Semazzi FHM (1980) Stationary barotropic flow induced by a mountain over a tropical belt. Mon Weather Rev 108:922–930CrossRefGoogle Scholar
  68. Thomson DJ (1982) A historical perspective of spectrum estimation. Proc IEEE 70:1055–1096CrossRefGoogle Scholar
  69. Todd MC, Washington R (1999) Circulation anomalies associated with tropical-temperate troughs in southern Africa and the south West Indian Ocean. Clim Dyn 15:937–951CrossRefGoogle Scholar
  70. Tozuka T, Luo J, Masson S, Yamagata T (2008) Tropical Indian Ocean variability revealed by self-organizing maps. Clim Dyn 31:333–343CrossRefGoogle Scholar
  71. von Storch H, Zwiers FW (2002) Statistical analysis in climate research. Cambridge University Press, CambridgeGoogle Scholar
  72. Waliser DE (2006) Intraseasonal variabilty. In: Wang B (ed) The Asian monsoon. Springer-Praxis, Berlin, pp 203–257CrossRefGoogle Scholar
  73. Waliser D, Sperber K, Hendon H, Kim D, Maloney E, Wheeler M, Weickmann K, Zhang C, Donner L, Gottschalck J, Higgins W, Kang I, Legler D, Moncrieff M, Schubert S, Stern W, Vitart F, Wang B, Wang W, Woolnough S (2009) MJO simulation diagnostics. J Clim 22:3006–3030CrossRefGoogle Scholar
  74. Washington R, Todd MC (1999) Tropical-temperate links in southern African and southwest Indian Ocean satellite-derived daily rainfall. Int J Climatol 19:1601–1616CrossRefGoogle Scholar
  75. Weickmann KM, Lussky GR, Kutzbach JE (1985) Intraseasonal (30–60 Day) fluctuations of outgoing longwave radiation and 250 mb streamfunction during northern winter. Mon Weather Rev 113:941–961CrossRefGoogle Scholar
  76. Wheeler MC, Hendon HH (2004) An all-season real-time multivariate MJO index: development of an index for monitoring and prediction. Mon Weather Rev 132:1917–1932CrossRefGoogle Scholar
  77. Woolnough SJ, Slingo JM, Hoskins BJ (2000) The relationship between convection and sea surface temperature on intraseasonal timescales. J Clim 13:2086–2104CrossRefGoogle Scholar
  78. World Meterological Organisation (2000) General meteorological standards and recommended practices, Appendix A, WMO Technical Regulations, WMO-No. 49, corrigendum. World Meteorological Organization, GenevaGoogle Scholar
  79. Xie P, Arkin PA (1997) Global precipitation: a 17-year monthly analysis based on gauge observations, satellite estimates and numerical model outputs. Bull Am Meteorol Soc 78:2539–2558CrossRefGoogle Scholar
  80. Zhang C (2005) Madden–Julian Oscillation. Rev Geophys. doi: 10.1029/2004RG000158
  81. Zhang C, Dong M (2004) Seasonality in the Madden–Julian Oscillation. J Clim 17:3169–3180CrossRefGoogle Scholar
  82. Zhang C, Hagos S (2009) Bi-modal structure and variability of large-scale diabetic heating in the tropics. J Atmos Sci 66:3621–3640CrossRefGoogle Scholar
  83. Zhang C, Ling J (2012) Potential vorticity of the Madden–Julian oscillation. J Atmos Sci 69:65–78CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Pascal Oettli
    • 1
  • Tomoki Tozuka
    • 1
  • Takeshi Izumo
    • 2
  • Francois A. Engelbrecht
    • 3
  • Toshio Yamagata
    • 4
  1. 1.Department of Earth and Planetary Science, Graduate School of ScienceThe University of TokyoTokyoJapan
  2. 2.IRD, LOCEANParisFrance
  3. 3.CSIR Natural Resources and the Environment, Climate Studies, Modelling and Environmental HealthPretoriaSouth Africa
  4. 4.Application Laboratory, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)YokohamaJapan

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