Mediterranean cloud system variability inferred from satellite observations

摘要

The variability of Mediterranean cloud systems isinvestigated using 8.5 years (from January 1987 to June 1995) ofTIROS-N Operational Vertical Sounder (TOVS) observations acquiredaboard the National Oceanic and Atmospheric Administration (NOAA)series of operational polar satellites. Cloud systems and troughs aredetected using retrievals of cloud top pressure (CTP) andtemperature of the lower stratosphere (TLS). Cloud systems have a typicalsize of a few hundred kilometres with a larger occurrence between Marchand October. The largest cloud systems occur preferentially in Mayand October and downstream of a midlatitude upper level trough.Finally, severe precipitation events over the Alpine region areassociated to a warm TLS anomaly upstream the cloud system, showingonce more the impact of the upper levels on the weather over thearea.