Study of the precipitation evolution in Catalonia using a mesoscale model (1971–2000)

摘要

In this work the MM5 mesoscale model is used in order to analyse the temporalevolution of the precipitation for the period 1971–2000 in Catalonia (NEIberian Peninsula). Three one-way nested domains with 135, 45 and15 km horizontal grid resolution and 23 vertical levels have beenused. The simulation is performed nesting MM5 into the ERA40 reanalyses.Dynamical nudging is applied to the first domain. However, nudging is notapplied in the second and third domains. In order to assess the performanceof the developed methodology (main spatio-temporal precipitationcharacteristics), the results obtained in each simulation are compared withthose obtained from ERA40 and observational data.The results show a climatologically reliable distribution of the simulatedprecipitation spatial patterns for annual, semi-annual, spring and summerprecipitation compared to those obtained from 1100 rain gauges covering thewhole study area. For winter and autumn the goodness of the results is muchlower. Furthermore, the results for 15-km outputs are better than the45-km ones. The simulations also reproduce well the evolution ofannual anomalies for Catalonia and the probability density function (PDF) ofmonthly mean precipitation. They also improve the precipitation outputs fromERA40, which present an important negative trend and a drier PDF for theperiod 1971–2000. On the other hand, extreme values are not well reproducedby the simulation. Despite this fact, hydric extremes derived from extremevalues (i.e. extreme rainy days and flood records) are well captured by themodel.