TITLE:
Observed and Future Spatiotemporal Changes of Rainfall Extreme Characteristics and Their Dynamic Driver in June-August Season over Africa
AUTHORS:
Asaminew Teshome, Jie Zhang, Teferi Demissie, Qianrong Ma
KEYWORDS:
Africa, Extremes, JJA, Observed, Projected
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.12 No.2,
April
7,
2022
ABSTRACT: Climate change has increased extreme events over
globe and the most robust occurrences of
concurrent drought and floods have become more common in Africa. This
study focuses on the observed and projected analysis of rainfall extremes of consecutive
dry day (CDD) and maximum monthly five day precipitation (RX5day) from Expert
Team on Climate Change Detection and Indices (ETCCDI) in June-August season
over Africa. The daily CORDEX Africa, reanalysis and CRU datasets were analyzed
for extreme trends under RCP4.5 and RCP8.5 scenarios for the periods of 1980 to
2100. The spatiotemporal variability, trend, and magnitude of JJA seasonal
rainfall performance exhibits a significant decreasing tendency over Eastern
Africa compared to West Africa. The observed results of consecutive dry day
(CDD) reveal that increasing trend and moreover RX5day shows that promising positive trend. Both
rainfall extremes are influenced by the combined effect of large scale indexes and appear to be
correlated negatively and positively with ENSO, NAO and AO. The CORDEX ensemble
mean projections
of JJA seasonal rainfall performance show a widespread significant change and the first mode
of EOF depicts that 13.8% and 24.9% under the RCP4.5 and the highest
variability is under RCP8.5 scenario. The projected CDD extreme exhibit an
increasing trend in the coming periods and the percentage change revealed that
increasing from 25.11%, 28.02% over West and 26.49%, 31.66% East Africa under
RCP4.5 and RCP8.5 scenarios respectively. This situation will exacerbate increasing
of frequent and intensified drought extremes over Africa. Additionally, the future RX5day indicated that mixed trend and revealed that increasing 3.72%, 2.54% over West and decreases -16.12%, -22.47% over East Africa under RCP4.5 and RCP8.5 respectively. Generally,
rainfall extremes of CDD are projected to increase and RX5day shows a mixed trend in the coming periods over Africa and
calls for
further verification by using high resolution datasets.