Fig. 5
From: A review of unusual VLF bursty-patches observed in Northern Finland for Earth, Planets and Space
Rising tone VLF bursty-patches at KAN. Power spectrum density at KAN on 13 February 2021 from a 05:00 to 09:00 UT (06:30–11:30 MLT) and from b 06:40 to 06:50 UT, between 0 and 10 kHz. Dashed and dotted horizontal white lines show, respectively, the local equatorial 0.5 fce and fce for the L-shell of KAN. Several VLF bursty-patches (black angle arrows and black shaped arrows) are observed above fce, particularly between 05:40 and 08:00 UT from 6 to 8.5 kHz. This event shows multiple hiss-like bursts with clear discrete rising tones