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Spatial patterns of Sahelian annual rainfall, 1961–1980

Räumliche Verteilungsformen des jährlichen Niederschlags im Sahel-Gebiet 1961–1980

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Summary

Based on 48 stations within and around the Sahel, individual annual rainfall values for 1961–80 are expressed as percentages of the 1931–60 average conditions. The main spatial patterns are then defined by a principal components analysis which incorporates most of the deficit years in the first component. Several regions of temporal change are defined also by a principal components analysis, and the characteristics of these regions are illustrated by cumulative deviation curves. The statistical significance of the sequence of dry years in the period 1970-80 is tested by the hypergeometric function, and the mean values for that period are compared with those for 1931–69.

Zusammenfassung

Für 48 Stationen im Sahel und darumherum werden die einzelnen jährlichen Niederschlagswerte für die Jahre 1961 bis 1980 in Prozenten der Mittelwerte von 1931–1960 ausgedrückt. Die Hauptformen der räumlichen Verteilungen werden dann durch die Hauptkomponenten-Analyse bestimmt, die das meiste der Defizitjahre in die erste Komponente einschließt. Einzelne Gebiete zeitlicher Änderung werden ebenfalls mit einer Hauptkomponenten-Analyse bestimmt und die Charakteristiken dieser Gebiete werden durch kumulative Abweichungskurven veranschaulicht. Die statistische Signifikanz der Folge von Trockenjahren in der Periode 1970–1980 wird mit der hypergeometrischen Funktion getestet und die Mittelwerte für diese Periode werden mit den Mittelwerten von 1931–1969 verglichen.

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Authors and Affiliations

  1. Department of Geography, University of Sheffield, S102 2TN, Sheffield, UK

    S. Gregory

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Gregory, S. Spatial patterns of Sahelian annual rainfall, 1961–1980. Arch. Met. Geoph. Biocl., Ser. B 31, 273–286 (1982). https://doi.org/10.1007/BF02278297

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  • DOI: https://doi.org/10.1007/BF02278297

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