Meteorological Aspects of Self‐Initiated Upward Lightning at the Säntis Tower (Switzerland). Issue 24 (26th December 2019)

• Record Type: Journal Article
• Authors: Pineda, Nicolau; Figueras i Ventura, Jordi; Romero, David; Mostajabi, Amirhossein; Azadifar, Mohammad; Sunjerga, Antonio; Rachidi, Farhad; Rubinstein, Marcos; Montanyà, Joan; van der Velde, Oscar; Altube, Patricia; Besic, Nikola; Grazioli, Jacopo; Germann, Urs; Williams, Earle R.
• Is Part Of: Journal of geophysical research. Volume 124:Issue 24(2019)
• Page Start: 14162
• Page End: 14183
• Publication Date: 2019-12-26
• Subjects: self‐initiated upward lightning -- Lightning Mapping Array -- polarimetric weather radar -- Hydrometeor Classification Product -- upward propagating leader; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2019JD030834
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Interest in exploring the meteorological conditions favoring upward lightning from tall man‐made structures has grown in recent years, largely due to the worldwide expansion of wind energy. To this end, instrumented towers existing around the world are the most suitable places to study upward lightning. In this context, an LMA network was deployed around the Säntis Mountain (northeast Switzerland) during the summer of 2017, in order to complement the long‐term measurements currently held at the Säntis telecommunications tower, a lightning hot spot in central Europe. This campaign allowed, for the first time, to gather a comprehensive set of observations of self‐initiated upward lightning emerging from the Tower. With the help of C‐band dual‐polarimetric radar data, the present work focuses on the meteorological conditions conductive to self‐initiated upward lightning from the Säntis. The analysis revealed that the upward propagating positively charged leaders spread mostly horizontal above the melting level, after an initial short vertical path from the tower tip. After this initial stage, the majority of upward leaders were followed by a sequence of negative return strokes. The inception upward lightning under a stratiform cloud shield would be favored by the low height of the charge structure. From the obtained results, it turns out that a key feature favoring self‐initiated upward lightning would be the proximity of the tower tip to the melting level. Plain Language Summary: In this paper, we present a multisensor analysis of upward lightning emerging from the Säntis tower, in Switzerland. This telecommunications tower is a lightning "hot spot" in central Europe, with a hundred of lightning striking the tower every year. For this reason, the tower has been instrumented, to study the current associated to the lightning discharges that hit the tower. To complement the current measurements, a Lightning Mapping Array network was deployed around the Säntis Mountain, during the summer of 2017. This campaign allowed, for the first time in Europe, to study the three‐dimensional structure of the upward leaders that initiate the process of the upward lightning from the tower. Moreover, with the help of dual‐polarimetric radar data from MeteoSwiss (Switzerland Federal Office for Meteorology), the present work analyzes the meteorological conditions that favor the triggering of upward lightning from the Säntis tower. Key Points: After a short vertical path, upward positive leaders turned horizontal to spread above the melting level Self‐initiated upward lightning occurred under stratiform precipitation, once the convective region of the system has passed away A key feature favoring self‐initiated upward lightning is the proximity of the tower tip to the melting level