Rain Gauge Accuracy at a High-Altitude Meteorological Station in Cathedral Peak

Abstract

Automatic rain gauges, such as tipping-bucket gauges, have generally replaced manual rain gauges in monitoring networks around the world. Both are susceptible to wind-induced errors. Shielding has been used to reduce these effects. The newly installed tipping-bucket rain gauges are not currently shielded in Cathedral Peak. The aim of this study was to improve understanding of the influence of shield and gauge design on rainfall measurement accuracy. The study was conducted at the Cathedral Peak Meteorological Station in the Drakensberg mountains, KwaZulu-Natal, South Africa. Three rain gauges, a historical shielded Snowdon, shielded, and ground-level tipping-bucket rain gauges, were installed alongside an unshielded tipping-bucket rain gauge. At the monthly scale, the Snowdon and unshielded rain gauges recorded 7%–8% and the shielded rain gauge 12% less than the ground-level rain gauge. At the event scale, the unshielded rain gauge recorded more rainfall for 58.47% of events than the shielded. Peak rainfall intensity was identified as the significant predictor variable affecting rainfall volume recorded by the rain gauges. From this study it was concluded that the use of a Nipher shielded rain gauge in the Cathedral Peak research catchments is ineffective.