JAMSTEC News
[Column] Drought over East Africa
December 08, 2021
Application Laboratory (APL)
Several world leading newspapers report an ensuing drought over East Africa as the seasonal rainfall during the short rains season has been very much below the normal level in November 2021 (https://fews.net/east-africa/, https://www.nature.com/articles/d41586-020-02698-3). Previous research studies at Application Laboratory, JAMSTEC and other international research centers (e.g. Black et al. 2003; Saji and Yamagata 2003; Behera et al. 2005) had found that the short rains season in East Africa is greatly influenced by the Indian Ocean Dipole (IOD, Saji et al. 1999). Some of the severe floods and devastating droughts are seen in positive and negative IOD years, respectively. For example, a strong negative IOD occurred during 2016 boreal summer and fall, which led to the drought over East Africa (Lu et al. 2018).
A negative IOD occurred in the boreal fall of 2021 (Fig 1). This event was well-predicted by the SINTEX-F prediction system (Fig. 2) of Application Laboratory, JAMSTEC.
- Fig. 2
- SINTEX-F predicted 2021 September-November sea surface temperature (left) and rainfall (right) anomalies from August 2021 initial conditions.
The negative IOD signal in the sea surface temperature anomalies starts decaying in December 2021 but the effect persists in the rainfall anomalies. In fact, the SINTEX-F model predictions from October initializations show severe rainfall deficiencies over East Africa during November 2021 – January 2022 (Fig. 3). This deficiency in seasonal rainfall is likely to continue at least until February of 2022 as predicted by the model (Fig. 3). Based on these predictions one can say that a serious situation is developing in the region related to this drier than normal rainfall season and there is a need for taking necessary mitigation measures to reduce the devastating impact of the drought on the human population there.
- Fig. 3
- SINTEX-F predicted November 2021-January 2022 (left) December 2021-February 2022 (right) rainfall anomalies from October 2021 initial conditions.
References:
Behera, S. K., J.-J. Luo, S. Masson, P. Delecluse, S. Gualdi, A. Navarra, and T. Yamagata, 2005: Paramount impact of the Indian Ocean dipole on the East African short rains: A CGCM study. J. Climate, 18, 4514–4530.
Black, E., J. Slingo, and K. R. Sperber, 2003: An observational study of the relationship between excessively strong short rains in coastal East Africa and Indian Ocean SST. Mon. Wea. Rev., 131 , 74–94.
Saji, N. H., and T. Yamagata, 2003: Possible impacts of Indian Ocean Dipole mode events on global climate. Climate Research, 25, 151-169.
Saji, N. H., B. N. Goswami, P. N. Vinayachandran, and T. Yamagata, 1999: A dipole mode in the tropical Indian Ocean. Nature, 401 , 360–363.
Lu, B., Ren, HL., Scaife, A.A. et al. An extreme negative Indian Ocean Dipole event in 2016: dynamics and predictability. Clim Dyn 51, 89–100 (2018). https://doi.org/10.1007/s00382-017-3908-2