Multi-sensor analysis of convective activity in Central Italy during the HyMeX SOP 1.1

A multi-sensor analysis of convective precipitation events that occurred in central Italy, in autumn 2012 during the HyMeX (Hydrological cycle in the Mediterranean eXperiment) Special Observation Period (SOP) 1.1 is presented. Various microphysical prop- 5 erties of liquid and solid hydrometeors were examined to assess their relationship with lightning activity. The instrumentation used consisted of a C-band dual-polarization weather radar, a 2-D video disdrometer, and a lightning network. A fuzzy logic based hydrometeor classification algorithm was tuned and optimized for the detection of graupel from C-band dual-polarization radar measurements. Graupel ice water content was 10 then retrieved and related to lightning activity. A linear correlation was found between the total mass of graupel above the 0! isothermal and the number of strokes detected by the lightning network in agreement with model outputs, which confirms the importance of ice in the electrical charging of convective clouds, although di?erences were noticed among events. Parameters of the gamma raindrop size distribution measured 15 by a 2-D video disdrometer, revealed the transition from convective to stratiform regime during the event and where related. However, lighting activity was not always recorded when the precipitation regime was classified as convective. More robust relationships were found relating lightning activity to graupel.