Intraseasonal rainfall variability over Madagascar

Clémence Macron (1) , Yves Richard (1) , Thomas Garot (2) , Miloud Bessafi (3) , Benjamin Pohl (1) , Adolphe Ratiarison (4) , Andrianaharimanana Razafindrabe (5)

1 BGS - Biogéosciences [UMR 6282]
2 SPACE - LATMOS
3 ENERGY Lab - Energy Lab
4 Laboratoire de la Dynamique de l’Atmosphère du Climat et des Océans
5 Laboratoire Hydraulique et énergétique

Using daily rain-gauge records for Madagascar and nearby islands, this paper investigates rainfall intraseasonal variability at local and regional scales during the austral summer season (November–February), as well as the respective influences of recurrent convective regimes over the South-West Indian Ocean (SWIO) and the Madden-Julian Oscillation (MJO). Our results show a general consistency between local-scale rainfall variability in Madagascar and regional-scale features of climate variability. The influence of Tropical-Temperate Troughs in their mature phase and/or their easternmost locations is first underlined. The development of such systems over Southern Africa and the Mozambique Chanel can be considered as precursors for Malagasy wet spells, especially over the southern part of the island. Regional and local effects of the MJO are weaker on average, and only concern the northwest of the island and the north of the Mozambique Chanel. MJO and convective regimes are finally shown to explain distinct fractions of regional rainfall variability.

Mots clés: Statistical methods; Seasonal variability; Indian Ocean; Geographic location; Circulation; Convection; Madden-Julian oscillation; Rainfall

Domaines: Météorologie

Clémence Macron, Yves Richard, Thomas Garot, Miloud Bessafi, Benjamin Pohl, et al.. Intraseasonal rainfall variability over Madagascar. Monthly Weather Review, 2016, 144 (5), pp.1877-1885. ⟨10.1175/MWR-D-15-0077.1⟩. ⟨hal-01182564⟩