Strong Dependence of Extreme Convective Precipitation Intensities on Gauge Network Density

Abstract

Extreme convective precipitation on subhourly scales is notoriously misrepresented in rain gauge-based observations, but uncertainties are weakly quantified at the 1 to 30 km scale. We employ a unique observing network, the high-density WegenerNet and surrounding operational rain gauge network in southeastern Austria, to sample convective precipitation extremes at these scales. By systematically constructing lower-density networks, we explore how estimated maximum area precipitation depends on observing station density. Using subhourly to hourly temporal resolution, we find a d−0.5(±0.1) power law decay of the event maximum area precipitation over distances d from 1 to 30 km, showing that operational gauge networks underrate extreme convective precipitation falling over small areas. Furthermore, extremes at point scale are found underestimated by operational networks by about 20%. We consider the dependencies representative for short-duration convective events over similar regions at midlatitudes and the results valuable for high-resolution climate model evaluation.