In November'02 an episode of intense precipitation impacted portions of Northern Italy, Switzerland, and the southern part of France causing the rise of lake and river levels and in some areas hazardous flooding. Rains began on 24 November in the western part of the Alps, over the Liguria (Genoa) and Lombardia (Milan) regions. Warm and humid air originating from the Mediterranean was driven northward towards the Alps where it met cold and dry air originating in the Atlantic eastern. An intense Sirocco wind was present throughout the Italian peninsula, raising surface temperatures up to 25^oC in northwest Sardinia (Alghero). On 25 November, the storm system moved towards the eastern area of the Alps, spawning intense thunderstorms, and in some cases hail, over Lombardia and Friuli. Heavy rains continued into 26 November when the precipitation terminated in response to subsidence from a high pressure system centered over eastern Europe. Observations suggest that the event featured extensive cold air damming against the Alps that enhanced the lifting over Milan. Since the 0C isotherm was only 2000 m above sea level, strong snowfall occurred over the Alps with accumulations between 250 and 400 cm. At Genoa, ~17 cm of rain was recorded on 24 November, and 29 cm on 26 November contributing to a 3-day total of some 46 cm. At Milan, ~24 cm of rain was observed for the 3-day period. A cloud resolving simulation of the event using the University of Wisconsin Nonhydrostatic Modeling System (UW-NMS) will be presented. The simulation is being performed as an entry to a Cloud Radiation Data Base (CRDB) used for satellite microwave precipitation retrieval. The CRDB is a collection of precipitating storm simulations from which the associated microphysics, thermodynamics, and dynamics are used as the physical underpinnings for rain retrieval algorithms. The robustness of this data base for Mediterranean regions applications will be discussed. Comparisons and contrasts of this simulation with simulations of other late-year flood-producing storms in the Mediterranean region will also be discussed.
The 24-26 November, 2002 Floods affecting Northern Italy: A Numerical Investigation
Dietrich S;Mugnai A;Panegrossi G;
2003
Abstract
In November'02 an episode of intense precipitation impacted portions of Northern Italy, Switzerland, and the southern part of France causing the rise of lake and river levels and in some areas hazardous flooding. Rains began on 24 November in the western part of the Alps, over the Liguria (Genoa) and Lombardia (Milan) regions. Warm and humid air originating from the Mediterranean was driven northward towards the Alps where it met cold and dry air originating in the Atlantic eastern. An intense Sirocco wind was present throughout the Italian peninsula, raising surface temperatures up to 25^oC in northwest Sardinia (Alghero). On 25 November, the storm system moved towards the eastern area of the Alps, spawning intense thunderstorms, and in some cases hail, over Lombardia and Friuli. Heavy rains continued into 26 November when the precipitation terminated in response to subsidence from a high pressure system centered over eastern Europe. Observations suggest that the event featured extensive cold air damming against the Alps that enhanced the lifting over Milan. Since the 0C isotherm was only 2000 m above sea level, strong snowfall occurred over the Alps with accumulations between 250 and 400 cm. At Genoa, ~17 cm of rain was recorded on 24 November, and 29 cm on 26 November contributing to a 3-day total of some 46 cm. At Milan, ~24 cm of rain was observed for the 3-day period. A cloud resolving simulation of the event using the University of Wisconsin Nonhydrostatic Modeling System (UW-NMS) will be presented. The simulation is being performed as an entry to a Cloud Radiation Data Base (CRDB) used for satellite microwave precipitation retrieval. The CRDB is a collection of precipitating storm simulations from which the associated microphysics, thermodynamics, and dynamics are used as the physical underpinnings for rain retrieval algorithms. The robustness of this data base for Mediterranean regions applications will be discussed. Comparisons and contrasts of this simulation with simulations of other late-year flood-producing storms in the Mediterranean region will also be discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
