1. a Institute of Acoustic ‘O.M. Corbino’ (CNR), ICES Group , Via Fosso del Cavaliere, I-00133, Rome, Italy
2. b Norwegian Institute for Air Research (NILU) , N-2027, Kjeller, Norway
3. c Norwegian Institute for Air Research (NILU) , N-9296, Troms⊘, Norway
4. d Norwegian Polar Institute (NP) , N-9005, Troms⊘, Norway