Akin-Tunde/west-africa-climate

Reproducible analysis of West African rainfall climatology, monsoon onset, SST linkages, and drought extremes, 2000-2025. # west-africa-climate Rainfall climatology, monsoon onset, sea-surface-temperature linkages, and drought extremes in West Africa, 2000–2025. This repository contains a reproducible, end-to-end climate analysis for West Africa (study area 10°S–25°N, 25°W–15°E), built from four public gridded datasets: **CHIRPS v2.0** monthly precipitation (0.05°), **CRU TS 4.08** monthly temperature (0.5°), **NOAA OISST** monthly sea-surface temperature (0.25°), and **NCEP Reanalysis 1** monthly 850 hPa winds. Six Python notebooks compute climatology and trends, monsoon onset and cessation, ocean–rainfall linkages, drought indices, atmospheric circulation, and a synthesis panel. All code runs on a machine with ~4 GB of free RAM thanks to memory-safe array handling; the figures and summary CSVs are generated automatically. License: **MIT** (see `LICENSE`). ## Key results | Question | Answer | |---|---| | Is rainfall trending? | Region-mean annual rainfall increases **+118.4 mm/decade** (R² = 0.11, p = 0.094, not significant at the 5% level over 26 years). The trend is strongly heterogeneous: the interior Sahel (Kano, Bamako, Akure) shows large positive local trends (+760 to +820 mm/decade, Kano p = 0.024), while coastal Lagos shows a modest +96 mm/decade. Only 31.9% of land grid cells have statistically significant trends. | | When does the monsoon arrive? | Coastal onset (Lagos, Akure) occurs around **DOY 57 (late February)** with a climatological annual cycle of roughly 1,200–1,500 mm/yr; onset trends at both sites are small and not significant (|p| > 0.75). | | Do Gulf of Guinea SSTs drive rainfall? | **No significant same-month link**: the map of detrended monthly GoG SST vs. detrended rainfall correlations is centred near zero (|r| < 0.3 everywhere), with no significant grid cells. ENSO (Niño-3.4 cold-tongue index) is only weakly linked to Sahel JJAS rainfall (r ≈ −0.1). Warm cold-tongue years are 2002, 2015, and 2023; cold years are 2000, 2011, and 2022 — matching the El Ni …