Solar cycle 21 (June 1976-Sep 1986)

IMF & geomagnetic parameters

Positive polarity (1976-1978)

Negative polarity (1981-1986)

Toward days

Away days

T-A

Toward days

Away days

T’-A’

No. of Days

Average

No. of Days

Average

Average

No. of Days

average

No. of Days

average

Average

IMF (nT)

265

6.28 ± 0.4

341

6.31 ± 0.5

−0.03 ± 0.7

730

7.31 ± 0.5

711

7.48 ± 0.5

−0.16 ± 0.7

aa

265

19.87 ± 2.2

341

22.44 ± 2

−2.57 ± 2.9

730

26.75 ± 1.7

711

26.13 ± 1.8

0.61 ± 2.5

Ap

265

11.76 ± 1.4

341

13.11 ± 1.7

−1.35 ± 2.2

730

16.72 ± 1.3

711

15.91 ± 1.2

0.81 ± 1.7

Kp

265

20.96 ± 1.4

341

23.07 ± 1.6

−2.11 ± 2.1

730

26.93 ± 1.3

711

26.46 ± 1.2

0.46 ± 1.8

DST

265

15.18 ± 0.6

341

18.58 ± 3.3

−3.39 ± 3.4

730

18.78 ± 1.8

711

17.81 ± 1.2

0.97 ± 2.2