Numerical simulations compared with measurements are used to investigate the effect of sea breezecirculation on the ozone accumulation over a highly industrialized peninsula in southern Italy, where high levels of ozoneconcentration are often registered. A frequent meteorological phenomenon in this region during weak summer synopticconditions is the development of complex sea breeze systems from the coastlines, with convergence areas within thepeninsula.A case study characterized by strong winds alternating with sea breeze circulations was selected.The simulations show that during weak synoptic conditions, sea breezes transport ozone and its precursors over landfrom the sea, as well as from the coastlines where the largest industrialized districts are localized. The overlapping breezeslead to ozone accumulation in the area where sea breeze convergence occurs. This may explain the high values of ozoneregistered close to the sea breeze convergence lines.The comparison between predictions and experimental data indicates that the numerical system successfully reproducesboth weather and ground level ozone concentration in different meteorological conditions, resulting in a fundamental toolfor both scientific comprehension of the evolution of air contaminants and interpretation of the monitoring data.

A prototype system for the analysis and investigation of extreme rainfall events

The spaceborne W-band (94 GHz) Cloud Profiling Radar (CPR) onboard the CloudSat (CS) satellite, which was launched in 2006, is providing valuable information about global cloud properties. This work aims at interpreting collocated time/space observations from CPR on CS and a ground C-band (5.6 GHz) Radar (GR), with the help of numerical simulations of electromagnetic scattering returns from populations of monodisperse spheres of ice and liquid water. Two cloud systems over Apulia region are investigated. CPR and GR images have been geo-referenced, then combined and displayed for analysis. The numerical simulations of the two radar reflectivities are used as a tool in the inversion procedure, aiming at identifying the hydrometeors, in their phase and size distribution, in the cloud volume simultaneously observed by the two radars. The possible vertical profiles of hydrometeors are presented.

The spaceborne W-band (94 GHz) Cloud Profiling Radar (CPR) onboard the CloudSat (CS) satellite, which was launched in 2006, is providing valuable information about global cloud properties. This work aims at interpreting collocated time/space observations from CPR on CS and a ground C-band (5.6 GHz) Radar (GR), with the help of numerical simulations of electromagnetic scattering returns from populations of spheres of ice and liquid water. One precipitating cloud system over Apulia region is investigated. CPR-CS and GR images have been geo-referenced, then combined and displayed for analysis. The numerical simulations of the two radar reflectivities are used as a tool in the inversion procedure, aiming at identifying the hydrometeors, in their phase and size distribution, in the cloud volume simultaneously observed by the two radars. The possible vertical profiles of hydrometeors are presented.

In recent years, a number of exceptional rainfall events of short / very short duration (from 15 minutes to about 2 hours) caused incidents and service interruptions due to landslides, collapses of bridges, and erosion of the ballast, along the Calabrian railway. RAMSES (RAilway Meteorological SEcurity System) is a pilot CNR project, recently co-funded by RFI S.p.A. and aimed at mitigating the risk along the railway. Forecasting of weather events responsible of heavy convective rainfall, even when provided with some advance, is not generally performed with reliable localization. In fact, objective limits of the numerical weather prediction derive from grid resolution, often exceeding the size of convective cells. These phenomena, whose recurrence periods seem to show a reduction due to climate changes, affect limited areas and are characterized by a very short life cycle. As a consequence, failures of hydraulic crossings are increasingly being recorded together with landslide-related debris invasion along the drainage network and slopes. RAMSES aims at improving short term (3-6 hours) weather forecasts and ground effects at local scale. The employed approach is base on synergistic and integrated operational tools to provide weather information on small-size basins. The system will also allow to promptly identify and track the short-term evolution (15-60 min) of convective cells, by means of imaging techniques based on quasi-real time radar and Meteosat data. The extension of the temporal horizon of the forecast up to three hours will be performed by using the Local Analysis and Prediction System (LAPS) model. This latter employs, as a "first guess", the output of the WRF numerical model: such analyses are updated and improved by means of observational data from different instruments (e.g. on land weather stations, radar, satellites, etc.). Finally, the assessment of ground effects will be accomplished for selected study areas, by means of landslide susceptibility mapping combined with hydrological, rainfall-runoff and hydraulic flow modeling.

Although different active and passive microwave satellite remote sensors have been successfully used for observations of clouds in the last years, the first spaceborne W band (94 GHz) Cloud Profiling Radar (CPR) onboard the CloudSat satellite, which was launched in 2006, provides valuable information about global cloud properties. This work aims at presenting results of an investigation of microphysical characteristics of clouds by combining observations from CPR and a ground C-band Radar (5.6 GHz). The analysis of the different return signals, recorded by the two radars, is useful for retrieving microphysical parameters of cloud systems.Two meteorological events occurred over Apulia region are investigated: one of them refers to a winter non-precipitating stratiform cloud, while the second one is related to a summer precipitating convective cloud. CloudSat and ground radar images have been geo-referenced using the same projection system, and almost simultaneously combined and displayed for analysis, according to a procedure described in details in a previous communication. In the top boundary and upper part of the system the W-band radar can observe with more accuracy, when compared to the C-band radar, while within a certain middle range of heights cloud profile by both instruments are well comparable. Two wavelength radar observations are compared with the output of numerical simulations of electromagnetic scattering, which allow fast computations of scattering properties of particles, by means of T-matrix implementation. The aim of this comparison is to find a suitable particle size distribution, which can reproduce the measured radar reflectivity for both frequencies. In this way, it is possible to obtain more information in order to better understand the microphysical properties of observed clouds.

Weather radar is a key tool to study microphysical properties of clouds and precipitation. In literature, quantitative comparisons have been made between space borne and ground radars to provide deep insight into the internal structure of clouds and cloud systems (Gaussiat et al. 2004). In particular in the last years, several studies have been published comparing data from W-band Cloud Profiling Radar (CPR) on board CloudSat (CS), operating at 94 GHz, and ground radar observations. Impressive progresses in cloud physics and dynamics investigations and benefits for applications, from nowcasting to climate studies (Stephens et al. 2002), have been reached by means of CS. Hudak et al. (2008) describe the validation data from the Environment Canada radar network and the precipitation detection algorithm in the CS product. Protat et al. (2009) compare CS reflectivities and basic ice cloud properties with ground-based radar observation, showing generally good agreements between the two datasets. Liu et al. (2010) compare the observed vertical structure of cloud occurrence and reflectivity distributions from CS and ground-based millimeter-wavelength cloud radar in the tropical western Pacific region.The present study aims at presenting method and preliminary results of a quantitative comparison between data from CS, and data from a ground radar, operating at the frequency of 5.6 GHz (hereinafter GR), to investigate microphysical properties of a cloud system. In particular we focus our attention on the ice component of the cloud, firstly because it is the main portion of the system and secondly it is well investigated by both of the available radars.