| 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 |