Significant hot and cold events at the Fabra Observatory, Barcelona (NE Spain)

Summary A long series of maximum and minimum daily temperatures recorded at the Fabra Observatory (Barcelona) from 1917 to 1998 has permitted a detailed study of significant hot and cold events, based on the crossing theory and on the Markovian process. The former allows us to obtain statistical distributions of the number of hot and cold events per year, the starting date and the magnitude of an event. The Poisson, the normal and the exponential distributions are the respective models. On the other hand, the Markovian process estimates probabilities for the duration of several hot and cold events above or below different temperature threshold levels. It should be stressed that the threshold levels, which define the significant hot and cold events, are almost coincident with those whose lengths follow a Markovian process. From a more applied point of view, two examples of hot and cold events of high magnitude are shown and their associated synoptic situations discussed. Some other typical synoptic situations leading to relevant hot and cold events in Barcelona and the surrounding areas are also summarised. Received March 1, 2001 Revised July 30, 2001