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Table 1.

Winter anomaly appearance in different regions.

Region N m F2 TEC (Kp ≤ 3) TEC (3 < Kp ≤ 6)
North American sector Always ≥90 s.f.u. ≥80 s.f.u.
East Siberian sector Always ≥120 s.f.u. ≥100 s.f.u.
Entire Northern Hemisphere Always ≥160 s.f.u. ≥110 s.f.u.
Australian sector ≥90 s.f.u. ≥170 s.f.u. ≥130 s.f.u.

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