F. Porcù

The Antalya 5 December 2002 Storm: Observations and Model Analysis

Abstract In the frame of this work, the storm that occurred on 5 December 2002 in Antalya, located on the southwestern Mediterranean Sea coast of Turkey, is analyzed. More than 230 mm of 24-h-accumulated rainfall have been reported during the event that produced floods in the area. The analysis is based on the results of model simulations with the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5). Observational data provided by the Tropical Rainfall Measuring Mission (TRMM) sensors (including the Lightning Imaging Sensor and TRMM Microwave Imager), Special Sensor Microwave Imager (SSM/I), Meteosat-7, and Met Office Arrival Time Difference (ATD) lightning network are used for both the comparison with the model results and also for the characterization of the storm. The synergetic use of all of this information was crucial for the description of the event. The maximum of precipitation was associated with the warm and moist air masses driven by a low-level jet over the area and imping...

Effects of Altitude on Maximum Raindrop Size and Fall Velocity as Limited by Collisional Breakup

AbstractCoalescence and breakup of drops are recognized as the main mechanisms determining raindrop size distributions on the ground. Full knowledge of these processes is hindered by the challenging difficulties both in the laboratory and tunnel experiments and during observations in the open air.In real rain breakup is mainly due to collision between drops of different sizes (collisional breakup) and occurs when the collisional kinetic energy (CKE) is not absorbed by the colliding drops. In this work, the authors observe and measure the dependence on altitude of the occurrence of collisional breakup in real rainfall events, and then estimate the corresponding limit terminal velocities of drops and their size when breakup significantly takes place.Data from Pludix, an X-band microwave disdrometer, were collected at three locations at different elevations: collisional breakup position in the power spectrum of Pludix increases toward higher frequencies with increasing altitude. Terminal velocities and sizes...

Evaluation of a Satellite Multispectral VIS-IR Daytime Statistical Rain-Rate Classifier and Comparison with Passive Microwave Rainfall Estimates

Abstract A daytime surface rain-rate classifier, based on artificial neural networks (ANNs), is proposed for the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board the Meteosat-8 geostationary satellite. It is developed over the British Isles and surrounding waters, where the Met Office radar network provided the “ground precipitation truth” for training and validation. The algorithm classifies rain rate in five classes at 15 min and 5 km of time and spatial resolution, and is applied on daytime hours in a summer and winter database. A further ANN application is restricted to hours between 1200 and 1400 UTC for which the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) on board the Aqua polar-orbiting satellite scans the U.K. area: ANN-classifier algorithms for the SEVIRI and AMSR-E data have been developed and the results have been compared. A reliable validation procedure is adopted to quantify the performance in view of the operational application of the daytime c...