TITLE:
Analysis of Spatiotemporal Trends and Variability in Precipitation Extremes over Tanzania during 1981-2023
AUTHORS:
Ombeni Habibu Msuya, Zhao Yu, Stephano Daniel Semgomba
KEYWORDS:
Extreme Precipitation, Precipitation Indices, Oceanic Systems, Tanzania
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.13 No.1,
January
20,
2025
ABSTRACT: This study examines the spatiotemporal trends and variability of precipitation extremes across Tanzania from 1981 to 2023, focusing on role of oceanic systems and large-scale climate phenomena. The analysis employed standardized extreme precipitation indices recommended by the Expert Team on Climate Change Detection and Indices. Spatial and temporal patterns were evaluated using empirical orthogonal function analysis, while Pearson correlation coefficients and the Mann-Kendall test were used to determ8ine the significance of trends and relationships. The results highlight pronounced spatial contrasts, with central and southern regions experiencing more intense and frequent extreme rainfall, including consecutive wet days, heavy precipitation events, and higher daily rainfall intensities. These regions exhibit significant upward trends, indicating heightened vulnerability to extreme wet conditions, while the northern areas experience fewer wet spells and lower overall precipitation. The first principal component captures a pattern of intensified precipitation in the southern and central regions, whereas the second principal component reveals a north-south gradient characterized by sustained moderate rainfall in the north and intense, short-duration rainfall in the south. Large-scale climate oscillations, including the Atlantic Multidecadal Oscillation, the El Niño-Southern Oscillation, the Indian Ocean Dipole, and the Pacific Decadal Oscillation, play a critical role in shaping regional precipitation extremes. These phenomena influence the frequency, spatial distribution, and intensity of rainfall through mechanisms such as atmospheric pressure anomalies, moisture convergence, and cyclonic activity. For instance, high-pressure systems in the North Pacific suppress rainfall, while cyclonic systems in the eastern Indian Ocean enhance convective activity and moisture availability.