The urban forcing on thermodynamical conditions can greatly influence the local evolution of the atmospheric boundary layer. Heat stored in an urban environment can produce noteworthy mesoscale perturbations of the lower atmosphere. The new generation of high-resolution numer- ical weather prediction models (NWP) is nowadays often applied also to urban areas. An accurate representation of cities is key role because of the cities’ influence on wind, temperature and water vapor content of the planetary bound- ary layer (PBL). The Advanced Weather Research and Fore- casting model WRF (ARW) has been used to reproduce the circulation in the urban area of Rome. A sensitivity study is performed using different PBL and surface schemes. The significant role of the surface forcing in the PBL evolution has been investigated by comparing model results with ob- servations coming from many instruments (lidar, sodar, sonic anemometer and surface stations). The impact of different ur- ban canopy models (UCMs) on the forecast has also been in- vestigated. One meteorological event will be presented, cho- sen as statistically relevant for the area of interest. The WRF- ARW model shows a tendency to overestimate the vertical transport of horizontal momentum from upper levels to low atmosphere if strong large-scale forcing occurs. This overes- timation is partially corrected by a local PBL scheme coupled with an advanced UCM. Moreover, a general underestima- tion of vertical motions has been verified.

The role of urban boundary layer investigated by high resolution models and ground based observations in Rome area: a step for understanding parameterizations potentialities.

FERRETTI, Rossella;
2014-01-01

Abstract

The urban forcing on thermodynamical conditions can greatly influence the local evolution of the atmospheric boundary layer. Heat stored in an urban environment can produce noteworthy mesoscale perturbations of the lower atmosphere. The new generation of high-resolution numer- ical weather prediction models (NWP) is nowadays often applied also to urban areas. An accurate representation of cities is key role because of the cities’ influence on wind, temperature and water vapor content of the planetary bound- ary layer (PBL). The Advanced Weather Research and Fore- casting model WRF (ARW) has been used to reproduce the circulation in the urban area of Rome. A sensitivity study is performed using different PBL and surface schemes. The significant role of the surface forcing in the PBL evolution has been investigated by comparing model results with ob- servations coming from many instruments (lidar, sodar, sonic anemometer and surface stations). The impact of different ur- ban canopy models (UCMs) on the forecast has also been in- vestigated. One meteorological event will be presented, cho- sen as statistically relevant for the area of interest. The WRF- ARW model shows a tendency to overestimate the vertical transport of horizontal momentum from upper levels to low atmosphere if strong large-scale forcing occurs. This overes- timation is partially corrected by a local PBL scheme coupled with an advanced UCM. Moreover, a general underestima- tion of vertical motions has been verified.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11697/1231
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