A multi‐year assessment of sub‐hourly gridded precipitation for Switzerland based on a blended radar—Rain‐gauge dataset

Abstract

Blended high-resolution sub-hourly precipitation fields are increasingly needed for nowcasting and automatic warnings systems. Here we present a 7-year (2012-2018) assessment of (5-min) precipitation characteristics for the topographically complex region of Switzerland. We use CombiPrecip, a blended radar-rain-gauge product that provides high resolution (1 km 2) hourly precipitation fields. Five-minute fields (CPCD), fine enough to disentangle even the shortest convective events from longer-lasting precipitation, are obtained by temporally disaggregating these hourly fields. A rain-gauge verification of the sub-hourly precipitation fields shows that CPCD outperforms the radar-only estimates both in terms of quantitative error and in detecting wet/extreme periods, making CPCD sufficiently accurate to be used with confidence as input fields for hydrological modelling or for regional model validation. The quantitative error of CombiPrecip at the 60 (10)-min timescale , as expressed by the scatter, is 40% (22%) lower than that of the radar-only product. Radar-gauge discrepancies are large and the quantitative error of CPCD increases by 30% when decreasing aggregation times from 60 to 10 min. Although summertime 5-min precipitation extremes are strongest and more frequent on average south of the Alps, where they contribute to approximately 10% of the seasonal total precipitation, the most intense extremes are observed over the Jura Mountains in the afternoon and the highest wet 5-min frequency in the Prealps around the same time. Intense precipitation is more evenly distributed throughout the day south of the Alps. Extreme intensity and frequency peaks 2 hr earlier in the Prealps, the Jura Mountains and the Alps (~1600 UTC) compared to the Swiss Plateau (~1800 UTC). Extremes are less intense and frequent at high elevations (>2,000 MASL) than over the Swiss Plateau (<800 MASL).

Object-based analysis of simulated thunderstorms in Switzerland: application and validation of automated thunderstorm tracking on simulation data

“…We showed comparisons for simulated and radar-derived hail properties; in future, liquid precipitation could also be considered through the use of disagregated precipitation fields (e.g. Barton et al, 2020).…”

The significance of monitoring high mountain environments to detect heavy precipitation hotspots: a case study in Gredos, Central Spain

“…phase change) in the course between radar detection and arrival to the ground if the radar is placed at the top of the mountain, or the attenuation of the radar signal in heavy rain (Germann and Joss 2004;Khanal et al 2019). An approach to overcome these limitations is the use of blended radar-rain gauge products, as recently shown for Switzerland by Barton et al (2020).…”

Object-based analysis of simulated thunderstorms in Switzerland: application and validation of automated thunderstorm tracking with simulation data

“…We showed comparisons for simulated and radarderived hail properties; in future, liquid precipitation could also be considered through the use of disaggregated precipitation fields (e.g. Barton et al, 2020). Further investigation would be required to analyse the sources of error where derived properties disagree.…”