SPATIAL AND TEMPORAL VARIABILITY OF PRECIPITATION IN SOUTHERN OF MADAGASCAR

Climatology and Weather

This research aims to analyze the spatial and temporal variability of precipitation in Southern of Madagascar. Precipitation data is reanalysis data in grid points (54 points), between January 01st, 1979 and December 31st, 2017. Various technics are used to characterize this variability. The Principal Component Analysis method makes it possible to represent individuals in the factorial plan. The first factor axis corresponds to precipitation and the second to the seasons of the year (winter and Southern summer). Then, the individuals are grouped according to the signs of their coordinates on the factorial plan. As a result, we get a subdivision into four zones: a zone of weak precipitation in Southern winter, a zone of weak precipitation in Southern summer, a zone of heavy precipitation in Southern winter and a zone of heavy precipitation in Southern summer. To optimize the regionalization, the representation on the factorial plan is combined with the K-Means and Fuzzy C-Means clustering methods. Then, another representation on the t-sne plan with perplexity parameter 5 also followed by the two previous clustering methods. All classifications are evaluated by Dunn's index. The best classifications are those of t-sne representation combined with the Fuzzy C-Means or K-Means clustering method. The final result of the spatial and temporal variability analysis of precipitation shows an East-West gradient of precipitation whether in summer or in Southern winter.

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