Absolute intensity of daytime whistlers at low and middle latitudes and its latitudinal variation

Main Article Content

M. Hayakawa
Y. Tanaka
K. Ohta
T. Okada

Abstract

The statistical study on the field intensity of daytime whistlers at low (geomag. lat. 25°) and middle (35°) latitudes has been made, based on a lot of data obtained by the field-analysis direction finding system based on the simultaneous measurement of two horizontal magnetic field components and one vertical electric field component. At low latitude, the maximum absolute intensity is estimated to be 250 μV/m, while the corresponding maximum intensity at middle latitude amounts to 600 μV/m, being about 2.4 times that at low latitude. This latitudinal variation of daytime intensity is interpreted in terms of the joint influence of (a) source activity, (b) magnetospheric propagation effect and (c) ionospheric transmission loss. As the result, it is found that whistlers at each station are attributed to ducted propagation in the magnetosphere and have exited the ionosphere close to each observing station, as determined by the direction finding results. Furthermore, the cloud distributions observed by meteorological satellites have yielded that the duct entrance point of whistlers at each station fall within the active thunderstorm region. Hence, we can conclude that daytime whistlers are originated in the active thunderstorms in each conjugate region, are trapped in field-aligned ducts and followed by nearly the vertical exit from the ionosphere at each station. Finally the latitudinal difference of the intensity is satisfactorily interpreted in terms of the difference in the ionospheric transmission loss on the assumption of the same source intensity at each conjugate point and of no amplification in the magnetosphere.


Google Scholar         ARK:/88439/y007596


 

Article Details

How to Cite
Hayakawa, M., Y. Tanaka, K. Ohta, and T. Okada. 1986. “Absolute Intensity of Daytime Whistlers at Low and Middle Latitudes and Its Latitudinal Variation”. Journal of Geophysics 59 (1), 67-72. https://journal.geophysicsjournal.com/JofG/article/view/230.
Bookmark and Share

References

Bullough, K., Sagredo, J.L. (1973) VLF goniometer observations at Halley Bay, Antarctica, I. The equipment and measurement of signal bearing. Planet. Space Sci. 21:899-912

Carpenter, D.L. (1980): Fast fluctuations in the arrival bearing of magnetospherically propagating signals from the Siple, Antarctica. J. Geophys. Res. 85:4157-4166

Carpenter, D.L., LaBelle, J.W. (1982) A study of whistlers correlated with bursts of electron precipitation near L = 2. J. Geophys. Res. 87:4427-4434

Cousins, M. (1972) Direction finding on whistlers and related VLF signals. Tech. Rep. SEL-72-013, Radioscience Lab., Stanford Univ.

Hayakawa, M., Ohtsu, J., Iwai, A. (1969) Occurrence rate and dispersion of whistlers during magnetically disturbed periods at lower latitudes. Rep. Ionosph. Space Res. Japan 23:9-20

Hayakawa, M., Tanaka, Y. (1978) On the propagation of low latitude whistlers. Rev. Geophys. Space Phys. 16:111-123

Hayakawa, M., Okada, T., Iwai, A. (1981a) Direction findings ofmediumlatitude whistlers and their propagation mechanism. J. Geophys. Res. 86:6939-6946

Hayakawa, M., Tanaka, Y., Okada, T., Iwai, A. (1981b) Goniometric direction finding for low-latitude whistlers and their propagation characteristics. J. Geophys. Res. 86:6781-6793

Hayakawa, M., Tanaka, Y., Okada, T., Ohtsu, J. (1983) Time scales of formation, lifetime and decay of whistler ducts at low latitudes. Ann. Geophysicae 1:515-518

Hayakawa, M., Ohta, K., Tanaka, Y. (1985) Further direction finding evidence on ducted propagation of low-latitude daytime whistlers and the duct structure To be published in Res. Lett. Atmosph. Electr.

Helliwell, R.A. (1965) Whistlers and Related Ionospheric Phenomena, p. 124. Stanford University Press

Helliwell, R.A., Katsufrakis, J.P., Trimpi, M.L. (1973) Whistler induced amplitude perturbation in VLF propagation. J. Geophys. Res. 78:4679-4688

Iwai, A., Outsu, J. (1958) On an investigation of the field intensity of whistling atmospherics. Proc. Res. Inst. Atmos., Nagoya Univ. 5:50-52

Leavitt, M.K., Carpenter, D.L., Seely, N.T., Padden, R.R., Doolittle, J.H. (1978) Initial results from a tracking direction finding receiver for whistler mode signals. J. Geophys. Res. 83:1601-1610

Lester, M., Smith, A.J. (1980) Whistler duct structure and formation. Planet. Space Sci. 28:645-654

Lohrey, B., Kaiser, A.B. (1979) Whistler induced anomalies in VLF propagation. J. Geophys. Res. 84:5121-5130

Matthews, J.P., Smith, A.J., Smith, I.D. (1979) A remote unmanned ELF/VLF goniometer receiver in Antarctica. Planet. Space Sci. 27:1391-1401

Ohta, K., Hayakawa, M., Tanaka, Y. (1984) Ducted propagation of daytime whistlers at low latitudes as deduced from the groundbased direction finding. J. Geophys. Res. 89:7557-7564

Okada, T., Iwai, A., Hayakawa, M. (1977) The measurement of incident and azimuthal angles and the polarization of whistlers at low latitudes. Planet. Space Sci. 25:233-241

Okada, T., Iwai, A. (1980) A new device for measuring polarization and field intensity of low-latitude whistlers. Trans. Inst. Electr. Engrs. Japan 100:21-28

Okada, T., Iwai, A., Hayakawa, M. (1981) A new whistler direction finder. J. Atmos. Terr. Phys. 43:679-691

Pitteway, M.L.V., Jespersen, J.L. (1966) A numerical study of the excitation, internal reflection and limiting polarization of whistler waves in the ionosphere. J. Atmos. Terr. Phys. 28:17-43

Sagredo, J.L., Bullough, K. (1973) VLF goniometer observations at Halley Bay, Antarctica, II. Magnetospheric structure deduced from whistler observation. Plant. Space. Sci. 21:913-923

Strangeways, H.J., Madden, R.A., Rycroft, M.J. (1983) High latitude observation of whistlers using three spaced goniometer receivers. J. Atmos. Terr. Phys. 45:387-399

Tanaka, Y. (1972) VLF hiss observed at Syowa Station, Antarctica, I. Observation of VLF hiss. Proc. Res. Inst. Atmos. Nagoya Univ. 19:33-61

Tanaka, Y., Hayakawa, M. (1973a) The effect of geomagnetic disturbances on duct propagation of low-latitude whistlers. J. Atmos. Terr. Phys. 35:1699-1703

Tanaka, Y., Hayakawa, M. (1973b) Storm-time characteristics of lowlatitude whistlers. Planet. Space Sci. 21:1997

Tanaka, Y., Nishino, M., Hayakawa, M. (1976) A study of VLF auroral hiss observed at Syowa, Antarctica. Mem. Natl Inst. Polar Res., Tokyo, Series A13 (Aeronomy), pp. 58

Tanaka, Y ., Hayakawa, M. (1980) Longitudinal effect in the enhancement of daytime whistler activity at low latitudes. Ann. Geophys. 36:577-585

Taylor, W.L. (1963) Radiation field characteristics of lightning discharges in the band 1 kc/s to 100 kc/s. J. Res. NBS, D. Radio Propagation 67D:539-550

Tsuruda, K., Hayashi, K. (1975) Direction finding technique for ellipitically polarized VLF electromagnetic waves and its application to the low latitude whistlers. J. Atmos. Terr. Phys. 37:1193-1202