Satellite-based characterization of convective growth and glaciation and its relationship to precipitation formation over Central Europe

Abstract

he growth phase of convective storms and their transition to maturity is investigated based on more than one hundred cases selected from the years 2012 to 2014 over Central Europe. Dynamical growth properties as well as cloud-top glaciation and microphysical characteristics are derived from the SEVIRI imaging radiometer aboard the geostationary Meteosat satellites. In addition, onset and intensity of surface precipitation are related to growth and glaciation processes using observations from the radar network of the German Weather Service. The majority of analyzed cases show a distinct maximum in cloud-top cooling rate, which is used here for temporal synchronization. Cloud growth spans a period of approximately half an hour. Glaciation rate indicators suggest that freezing 15 min prior to the maximum cooling plays an important role in invigorating convective updrafts through the release of latent heat. Smaller ice particles are found for larger cloud-top cooling, which provides observational evidence that ice particles form later and have less time to grow in stronger convective updrafts. Furthermore, maximum cloud-top height, anvil expansion rate, maximum precipitation intensity and core size are found to be positively correlated. With respect to the onset of precipitation, our analysis shows a high probability that significant precipitation already occurs 30 min prior to maximum cloud-top cooling.