Occurrence of F region echoes for the polar cap SuperDARN radars

Earth, Planets and Space

Table 2 Linear fit line slopes of the echo occurrence decline in 2015–2017 (Fig. 4c, d) for various time*** sectors and radars. The time sectors were selected according to the local solar time ± 3 h

	Echo occurrence decrease slope in % per year (bands)
	CLY	RKN	INV	DCE	MCM	SPS	AVG
Night (0 ± 3) LT	− 8.19	− 5.30	− 6.16	− 6.69	− 5.59	− 4.76	− 6.11
Dawn (9 ± 3) LT	− 5.91	− 2.52	− 5.17	− 8.16	− 5.86	− 6.04	− 5.61
Day (12 ± 3) LT	− 5.65	− 5.55	− 7.50	− 10.32	− 10.39	− 6.58	− 7.67
Dusk (18 ± 3) LT	− 7.63	− 5.13	− 5.53	− 9.85	− 11.16	− 8.11	− 7.90
Afternoon (15 ± 3) LT	− 6.3	− 4.5	− 7.0	− 10.4	− 10.8	− 9.2	− 8.03
Average (0 ± 24) LT	− 6.84	− 4.63	− 6.09	− 8.75	− 8.25	− 6.37	− 6.82