Differentiating lightning in winter and summer with characteristics of the wind field and mass field

Abstract

Abstract. Lightning in winter (December–January–February, DJF) is rare compared to lightning in summer (June–July–August, JJA) in central Europe north of the Alps. The conventional explanation attributes the scarcity of lightning in winter to seasonally low values of variables that create favorable conditions in summer. Here we systematically examine whether different meteorological processes are at play in winter. We use cluster analysis and principal component analysis and find physically meaningful groups in ERA5 atmospheric reanalysis data and lightning data for northern Germany. Two thunderstorm types emerged: wind-field thunderstorms and CAPE (convective available potential energy) thunderstorms. Wind-field thunderstorms are characterized by increased wind speeds, high cloud shear, large dissipation of kinetic energy in the boundary layer, and moderate temperatures. Clouds are close to the ground, and a relatively large fraction of the clouds are warmer than −10 ∘C. CAPE thunderstorms are characterized by increased convective available potential energy (CAPE), the presence of convective inhibition (CIN), high temperatures, and accompanying large amounts of water vapor. Large amounts of cloud-physics variables related to charge separation such as ice particles or cloud base height further differentiate both wind-field thunderstorms and CAPE thunderstorms. Lightning in winter originates in wind-field thunderstorms, whereas lightning in summer originates mostly in CAPE thunderstorms and only a small fraction in wind-field thunderstorms. Consequently, typical weather situations of wind-field thunderstorms in the study area in northern Germany are strong westerlies with embedded cyclones. For CAPE thunderstorms, the area is typically on the anticyclonic side of a southwesterly jet.

Thunderstorm detection from GPM IMERG rainfall: Climatology of dynamical and thermodynamical processes over India

“…It may be noted that the horizontal resolution of ERA5 data may not be sufficient to resolve the individual branches of updrafts and downdrafts. However, the signature of convection can be presented in the averaged vertical velocity value within the grid (Calvo‐Sancho et al, 2022; Morgenstern et al, 2023). The thunderstorms composites of vertical velocities are significantly lower than the previous observational (e.g., Adler & Fenn, 1979; Marshall et al, 1995) and modelling studies (e.g., Ogura & Takahashi, 1971; Osuri et al, 2017; Rotunno, 1981) and it could be mainly due to the coarser resolution of the ERA5 analysis and the layer of the averaging.…”

Thunderstorm Types in Europe

“…This supports our finding of the very diverse wind-field thunderstorm conditions. Stucke et al (2022) relate our two thunderstorm types as described in Morgenstern et al (2022a) to upward lightning at two alpine towers and find that most upward lightning occurs in wind-field thunderstorm conditions. In general, thunderstorm frequencies under different synoptic conditions are often described (e.g., Wapler and James, 2015;Enno et al, 2014;Bielec, 2001;Kolendowicz, 2006) and regional thunderstorm differences are often subject of classical climatologies as mentioned in the introduction.…”

“…Even though the European lightning patterns are in general well described (e.g., Wapler and James, 2015;Enno et al, 2014), it is less known how winter lightning differs meteorologically from lightning in summer. Morgenstern et al (2022a) found that thunderstorms in the cold season differ physically from thunderstorms in the warm season when studying a small observational region in northern Germany. They describe wind-field thunderstorms dominant in winter in contrast to CAPE (mass-field) thunderstorms typical for summer.…”

Deep convection, lightning activity and population impact over northwest Mexico: Coastal hotspots from 2009 to 2018

“…Based on lightning measurements, recent studies have focused on climatologies of the electrical activity from a global perspective (e.g., Albrecht et al, 2016; Kaplan & Lau, 2021; Peterson et al, 2021; Virts et al, 2013) or continental scale, such as Asia (Dewan et al, 2018) and Europe (Morgenstern et al, 2022). In North America as part of the monsoon season, lightning records have been examined to identify areas of high frequency west of the SMO and over the GOC adjacent to the mainland of NWM (Holle et al, 2016; Holle & Murphy, 2015).…”