Precipitation isotope dataset (δ¹⁸O, δ²H, d-excess) from southwestern Ethiopia

This dataset contains daily precipitation isotope measurements (δ¹⁸O, δ²H, and d-excess) and corresponding precipitation amounts from four observation sites in southwestern Ethiopia: Jimma (36.17°E, 7.84°N, 1711 m), Hosaena (37.52°E, 7.33°N, 2313 m), Jinka (36.56°E, 5.78°N, 1384 m), and Omorate (36.05°E, 4.80°N, 365 m). All sites are located within the northeast-southwest-oriented Omo Gibe River basin and operated by the Ethiopian National Meteorological Agency. A total of 889 precipitation samples were collected between June 2022 and June 2024 using a Palmex Precipitation collection device (Gröning et al., 2012). Samples were collected daily between 9:00 and 11:00 am, stored in glass vials with polycone seal caps wrapped with Parafilm to prevent evaporation, and measured by a Picarro L2130-i liquid water isotope analyzer via cavity ring-down spectroscopy (CRDS) at the University of Dayton. All isotopic results are reported as δ-notation relative to Vienna Standard Mean Ocean Water (VSMOW). Analytical precision is 0.1‰ for δ¹⁸O and 0.4‰ for δ²H. Due to the absence of precipitation samples at Jimma during June 2023–June 2024, 218 sets of precipitation isotopic data (δ¹⁸O and d-excess) between August 2012 and September 2013 was supplemented from Bedaso et al. (2020). Variables included:- Date: Sampling date (MM/DD/YYYY format)- δ¹⁸O (‰): Oxygen isotope ratio relative to VSMOW- δ²H (δD) (‰): Hydrogen isotope ratio relative to VSMOW- d-excess (‰): Deuterium excess calculated as δ²H - 8×δ¹⁸O- Precipitation (mm): Daily precipitation amount- Notes: Data source annotations