Abstract
Abstract. It is well established that using kilometer scale grid resolution for simulations of weather systems in weather and climate models enhances their realism. This study explores heavy- and extreme-precipitation characteristics over the Nordic region generated by the regional climate model HARMONIE-Climate (HCLIM). Two model setups of HCLIM are used: ERA-Interim-driven HCLIM12 spanning over Europe at 12 km grid spacing with a convection parameterization scheme and HCLIM3 spanning over the Nordic region with 3 km grid spacing and explicitly resolved deep convection. The HCLIM simulations are evaluated against a unique and comprehensive set of gridded and in situ observation datasets for the warm season from April to September regarding their ability to reproduce sub-daily and daily heavy-precipitation statistics across the Nordic region. Both model setups are able to capture the daily heavy-precipitation characteristics in the analyzed region. At the sub-daily scale, HCLIM3 clearly improves the statistics of occurrence of the most intense heavy-precipitation events and the amplitude and timing of the diurnal cycle of these events compared to its forcing of HCLIM12. Extreme value analysis shows that HCLIM3 provides added value in capturing sub-daily return levels compared to HCLIM12, which fails to produce the most extreme events. The results indicate clear benefits of the convection-permitting model in simulating heavy and extreme precipitation in the present-day climate, therefore, offering a motivating way forward to investigate the climate change impacts in the region.
Highlights
Precipitation extremes represent a major environmental and socioeconomic hazard worldwide, and the Nordic region is no exception
The differences compared to E-OBS in daily heavy precipitation seem to be larger in HCLIM3 than in HCLIM12 in the current study
We analyzed the characteristics of heavy and extreme precipitation in 21-year-long convection-permitting climate simulations with non-hydrostatic dynamics at a 3 km grid spacing (HCLIM3) and compared them with climate simulations performed with 12 km grid spacing, hydrostatic dynamics, and parameterized convection (HCLIM12)
Summary
Precipitation extremes represent a major environmental and socioeconomic hazard worldwide, and the Nordic region is no exception. Locally concentrated intense precipitation can cause flooding in rivers or urban settings, landslides, erosion events, and damages to infrastructure. The three main weather situations producing heavy precipitation within the Nordic region consist of the strong vertical lifting of moist air masses in connection with fronts, within convective cells, or enhanced by orography (Førland et al, 1998). The accumulated rainfall reached ∼ 150 mm within 6 h. Such extreme events are rare, previous studies have shown that precipitation extremes have become more frequent globally and in Europe over recent decades
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