Extraction of breakpoints from radar-estimated rainfall fields

The breakpoint format for rainfall data, by recording the rainrate and the times when the rainrate changes, consists of variable length periods during which rain of constant intensity fell. It is compact and retains a level o f detail equivalent to that found in high temporal resolution data. However , breakpoint data are available only at the relatively few locations where automatic raingauges produce pluviographs. On the other hand radar observat ions of rainfall provide precipitation data at a high spatial density but a t poor time resolution. Advantage can be taken of this high spatial density to give more locations where breakpoints are available through interpolati on between the radar images to provide precipitation data at sufficient tem poral resolution for the extraction of breakpoints. The interpolation schem e, based on the PARAPLUIE method, detects the movement and evolution of pre cipitating echoes to provide additional interpolated radar images. Breakpoi nts, extracted at pixels of the images that contain raingauges, showed simi lar overall accumulations and characteristics when compared with those of t he collocated raingauges. The similarity is particularly so for gauges with in a 50 km radius of the radar where the spatial resolution of the radar an d the temporal resolution of the raingauges are equivalent.