1. a Institute of Atmospheric Sciences and Climate (ISAC‐CNR) , Via Gobetti, 101, 40129 Bologna, Italy
2. b Geophysics Centre of Evora (CGE) , University of Évora , Rua Romão Ramalho, 59, 7000 Évora, Portugal
3. c STIL‐BAS , Base Observatory , 6000 Stara Zagora, Bulgaria
4. d University of Aquila , Via Vetoio Località Coppito, 67100 L'Aquila, Italy
5. e University of Frankfurt , Senckenberganlage 31, 60325 Frankfurt am Main, Germany
6. f IFAC‐CNR , Via Panciatichi, 64, 50127, Florence, Italy