Spatio-temporal investigations of monsoon precipitation and its historical and future trend over Sudan

Abstract

Understanding the ongoing and possible future changes in monsoon rainfall is vital for the sustainable planning and development of Sudanese agriculture. This study uses monthly rainfall recorded at 22 locations for the period 1960–2019 and future projections based on an ensemble of 3 global climate models (GCMs) for the period 2030–2089 to assess historical and future trends of rainfall in Sudan. Sen's slope estimator and Mann–Kendall (MK) test were used to estimate trends and their significance, respectively. The temporal coverage was divided equally into 30-year slices: periods A (1960–1989), B (1990–2019), then both combined into period C (1960–2019) for historical times, and periods D (2030–2059), E (2060–2089), and F (2030–2089) for the future. The future precipitation projection was evaluated from two Shared Socioeconomic Pathway (SSP) scenarios (SSP2-4.5 and SSP5-8.5) from the Coupled Model Intercomparison Project 6 (CMIP6). The results showed a countrywide decreasing trend in period A and an increasing trend in period B. The increasing trend in period B led to an overall positive trend for period C, except at a few stations. The future trend under SSP2-4.5 revealed a possible continuation of the cyclic pattern of the historical period. In contrast, SSP5-8.5 revealed a dominant increasing trend in rainfall for the period 2030–2089.