Intensiva regn i Malmö / Intensive storms in Malmö
Short-term intensive storms of duration up to an hour the years 1980–2007 from rain gauges in Malmö have been analyzed to find intensities of long return periods. Non-dependent observations from different stations have been combined into a series to which probability functions have been adjusted. The extreme events have been investigated individually. The reliability of rain measurements is discussed. In order to investigate whether rain intensities are different today compared to back in time, new and old rain data have been compared. Trends over the last 20–25 years have been computed for two stations. It is found that 10–25 year long rain series from single stations are too short to give good estimates of rains of long recurrence time, since a single event influences very much. However, there is a good fit to theoretical distributions if data from many stations are combined; the number of station year increases. The largest observed rains in Malmö in the investigated period have a return period of about 100 year. Rains of shorter return period than 10 year can be given as a simple relation of duration and return period. Rain intensity curves 50 years old do not differ much from those derived from new data. It is not possible to draw any conclusions about trends.