A new daily gridded precipitation dataset for the island of Ireland

Reliable high-resolution precipitation datasets are essential for climate analysis, hydrological modelling, and the assessment of climate extremes. Many existing gridded rainfall products are limited by national boundaries, making it difficult to carry out consistent regional-scale climate and hydrological assessments across the island of Ireland. Here, we present a new daily gridded rainfall product developed using a homogenous methodology across the entire island of Ireland. The dataset covers the period 1980-2020 and is based on rain gauge observations from Met Éireann and UK Met Office. The gridded product is generated using a high-resolution climatological interpolation framework based on inverse distance weighting (IDW) regression, with elevation included as a covariate. This approach allows the dataset to capture fine-scale spatial variability associated with orography, while preserving daily variability and extreme rainfall events. The daily grids are first produced at 1km x 1km resolution and then resampled to a common 0.1deg x 0.1deg resolution for comparison with other gridded datasets. To assess the quality of the product, we first validate the gridded rainfall estimates using observations from a crowd-sourced citizens rain gauges from the weather observation website, providing independent evaluation of the dataset. We then evaluate the dataset through grid-to-grid comparisons with Met Éireann daily grids and other widely used regional products such as E-OBS and Multi-Source Weighted-Ensemble Precipitation (MSWEP), focusing on annual and seasonal rainfall patterns, spatial biases, and selected storm events. The new datasets provides a spatially consistent representation of daily rainfall across the island of Ireland and offers a valuable resource for climate variability studies, extreme event analysis, and hydrological applications.