Satellite-Based Characterization of Convective Growth and Glaciation and Its Relationship to Precipitation Formation over Central Europe

Abstract

The growth phase of convective storms and their transition to maturity is investigated based on more than 100 cases selected from the years 2012–14 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 shows 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, this analysis shows a high probability that significant precipitation already occurs 30 min prior to maximum cloud-top cooling.

Detection of Mixed‐Phase Convective Clouds by a Binary Phase Information From the Passive Geostationary Instrument SEVIRI

“…Several algorithms track cloud entities and cloud microphysical properties with geostationary satellites (Berendes et al, 2008;Bennartz & Schroeder, 2012;Bley et al, 2016;Guilbert & Lin, 2007;Patou et al, 2018;Senf et al, 2015;Senf & Deneke, 2017;Zhu et al, 2017;Zinner et al, 2008). The information on r e could be used to detect mixed-phase clouds.…”

“…We require that each tracked cloud has its coldest pixel at least 30 min in the liquid phase and ice phase to be able to observe the phase transition. We define a reference time as the time for which the coldest pixel changes from liquid to ice, the process that all tracked clouds have in common, and is taken for synchronization (Mecikalski et al, 2016;Senf & Deneke, 2017).…”

Distribution and Variability of Satellite‐Derived Signals of Isolated Convection Initiation Events Over Central Eastern China

“…An isolated storm is declared when a newborn storm cell, without a nearby (within 10 km in this study) preexisting storm or storm anvil (≥10 dB Z ), reaches 35 dB Z and lasts over 30 min, and its CI time is defined as the first appearance of ≥35 dB Z radar reflectivity. The 35 dB Z criterion has been widely used in previous studies to define CI (e.g., Mecikalski et al, ; Mecikalski & Bedka, ; Roberts & Rutledge, ; Senf & Deneke, ; Walker et al, ).…”

“…These traits include the following: (1) signal location, (2) signal formation time (the aforementioned scan time T ), (3) CI time (the occurrence time of isolated CI in radar observations corresponding to a satellite‐derived CI signal), and (4) multispectral information.To obtain multispectral information for each satellite‐derived CI signal, other IR channel measurements from the S‐VISSR were also used besides BT IR1 . Previous efforts have shown great promise in relating IR “interest fields” (a series of spectral and temporal differencing fields) to the physical attributes of developing cumulus clouds undergoing CI (e.g., Mecikalski et al, , , ; Mecikalski & Bedka, ; Senf & Deneke, ; Siewert et al, ). Since the S‐VISSR has four IR channels (Table ), the available interest fields from FY‐2E include BT IR1 , BTD IR2−IR1 , BTD IR3−IR1 , BTD IR3−IR2 , BTD IR4−IR1 , and their respective time trends.…”

“…Journal of Geophysical Research: Atmospheres 10.1002/2017JD026946 studies to define CI (e.g., Mecikalski et al, 2015;Mecikalski & Bedka, 2006;Roberts & Rutledge, 2003;Senf & Deneke, 2017;Walker et al, 2012).…”