Interannual characteristics of rainfall over Madagascar and its relationship with the Indian Ocean sea surface temperature variation
Abstract
Understanding rainfall variability over a region is essential for economic development since it contributes to managing climate-sensitive sectors. This study assesses the interannual characteristics of rainfall over Madagascar and the possible influence of the Indian Ocean (IO) on rainfall patterns between 1950 and 2018, using monthly rainfall data from the Climatic Research Unit.
The singular value decomposition analysis was used to examine the effect of IO's sea surface temperature (SST) on the rainfall variability, followed by a composite analysis of vertically integrated moisture flux. Overall, both the wet and dry seasons showed a slight decrease in rainfall trends during the past 69 years.
During the wet (dry) season, the central and southeastern (western) IO SST were positively correlated with Madagascar's rainfall. The covariability analysis showed that a positive phase of the Subtropical Indian Ocean Dipole or Indian Ocean Dipole results in increased rainfall over the northwestern (northern) and southern parts of Madagascar during the wet (dry) season.
The composite analysis suggests that enhanced (decreased) rainfall during the wet (dry) years of the wet and dry seasons in Madagascar is linked to a strong moisture convergence (divergence) accompanied by strong easterlies (anticyclonic circulation) over the northwestern (southern) IO. The study findings could drive further studies on other likely factors that impact the country's rainfall.