Letter | Published:

Whistlers and Solar Activity

Naturevolume 193pages666667 (1962) | Download Citation



INVESTIGATING the International Geophysical Year data for 4 years from July 1, 1957, observed at Toyokawa (geomag. co-ords.: + 24.5°, 203.5°) and at Wakkanai (geomag. co-ords.: + 35.3°, 206.0°), I noticed a remarkable tendency of the frequency increase of occurrence of whistlers, year by year, in accordance with the decrease of sunspot number as shown in Fig. 1, where (1) shows the total number of occurrence of whistlers at Wakkanai during 5 winter months, November–March; (2) sum of monthly mean sunspot number during that period; (2′) the mean of sunspot number in one year; (3) the maximum number of occurrence of whistlers per month at Wakkanai in winter; (4) the same with (1) at Toyokawa; (5) the same with (3) at Toyokawa.

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  1. 1

    Kimpara, A., Rep. Iono. Space Res. Japan, 14, 160 (1960).

  2. 2

    Kimpara, A., Proc. Res. Inst. Atmospherics, Nagoya Univ., 7, 40 (1960).

  3. 3

    Austin, L. W., Proc. Inst. Rad. Eng., 15, 825 (1927).

  4. 4

    Helliwell, R. A., J. Res. Nat. Bur. Stand., 64, D, 642 (1960).

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  1. Research Institute of Atmospherics, Nagoya University, Toyokawa, Aichi-ken, Japan



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