Abstract
The average profile of Forbush decreases, produced by eastern-, central- and western-region solar flares is obtained separately by superposed epoch analysis for the periods 1966–1969 (qA < 0) and 1971–1979 (qA > 0). It is observed that the recovery of an average Forbush decrease from the maximum depression level is faster for the situation qA > 0 than for the situation qA < 0. This is in accordance with expectations from the drift theory. It is also observed that the drift effect is more pronounced for western-flare Forbush decreases which, of course, have a smaller magnitude compared to eastern- and central-flare Forbush decreases.
The average profiles of simple and complex type Forbush decreases are also obtained separately for three periods 1965–1979, 1971–1979, and 1981–1987. It is found that the average profiles of simple and complex type Forbush decreases observed during the period 1965–1969 and 1971– 1979 are quite in agreement with drift theory. The anomalous behavior of average Forbush-decrease profiles during the period 1981–1987, especially in simple type Forbush decreases, is also explained by a drift current sheet tilt model.
Similar content being viewed by others
References
Dodson, H. W. and Hedeman, E. R.: 1971, Report UAG-14 World Data Centre A, Boulder, CO.
Dodson, H. W. and Hedeman, E. R.: 1975, Report UAG-52, WDC-A Boulder, CO.
Dodson, H. W. and Hedeman, E. R.: 1985, Report UAG-80 WDC-A, Boulder, CO.
Forbush, S. E.: 1954, J.Geophys. Res. 59, 2914.
Forbush, S. E.: 1958, J. Geophys. Res. 63, 651.
Garcia-Munoz, M., Meyer, P., Pyle, K.R. and Simpson, J. A.: 1986, J. Geophys. Res. 19, 2858.
Jokipii, J. R., Levy, E. H., and Hubbard, W. B.: 1977, Astrophys. J. 213, 861.
Jokipii, J. R. and Kopriva, D. A.: 1979, Astrophys. J. 234, 384.
Jokipii, J. R. and Thomas, B.T.: 1981, Astrophys. J. 243, 1115.
Kota, J. and Jokipii, J. R.: 1983, Astrophys. J. 265, 573.
Lee, M. A. and Fisk, L. A.: 1981, Astrophys. J. 248, 836.
Lockwood, J. A., Webber, W. R., Jokipii, J. R.: 1986, J. Geophys. Res. 91, 2851.
Mc-Donald, F. B., Nand, Lal, and McGuire, R. E.: 1993, J. Geophys. Res. 98, 1243.
Mulder, M. S. and Moraal, H.: 1986, Astrophys. J. 303, L75.
Nagashima, K. and Morishita, I.: 1980, Planetary Space Sci. 28, 177.
Perko, J. S. and Burlaga, L. F.: 1992, J. Geophys. Res. 97, 4305.
Potgieter, M. S. and Moraal, H.: 1985, Astrophys. J. 294, 425.
Smith, E. J. and Thomas, B. T.: 1986, J. Geophys. Res. 91, 2933.
Webber, W. R. and Lockwood, J. A.: 1988, J. Geophys. Res. 93, 8735.
Yoshida, S. and Akasofu, S. I.: 1965, Planetary Space Sci. 13, 435.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Rana, D.S., Sharma, N.K. & Yadav, R.S. The effect of gradient and curvature drifts on Forbush decreases. Sol Phys 167, 371–380 (1996). https://doi.org/10.1007/BF00146346
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00146346