A rule based quality control method for hourly rainfall data and a 1 km resolution gridded hourly rainfall dataset for Great Britain: CEH-GEAR1hr

Abstract High-resolution gridded precipitation products are rare globally, particularly below a daily time-step, yet many hydrological applications require, or can be improved by, a higher temporal resolution of rainfall data. Here, we present a new 1 km resolution gridded hourly rainfall dataset for Great Britain (Gridded estimates of hourly areal rainfall for Great Britain (1990–2014) [CEH-GEAR1hr]) using data from over 1900 quality controlled rainfall gauges, which improves upon the current UK national gridded precipitation datasets at daily time-step. We extend and automate a quality control (QC) procedure to permit the use of hourly data for 1990–2014 and independently validate the QC using daily rainfall data and recorded historic events. Our two-tiered validation approach, at daily and hourly timescales, indicates that spurious extreme values are excluded from the resultant dataset, while legitimate values are preserved. We use a nearest neighbour interpolation scheme to derive gridded hourly rainfall values at 1 km resolution, to temporally disaggregate the CEH-GEAR daily gridded dataset and produce an hourly dataset with consistent daily totals. This provides a unique resource for hydrological applications in Great Britain. The CEH-GEAR1hr dataset, associated metadata and QC information, will be freely available from the Environmental Information Data Centre (EIDC) and hosted alongside the daily and monthly CEH-GEAR product.