Abstract
Observations of the Sun performed at 37 GHz with the 14-m radio telescope of the Metsähovi Radio Observatory were analyzed. Rotation velocities were determined, tracing Low Temperature Regions (LTRs) in the years 1979–1980, 1981–1982, 1987–1988, and 1989–1991. Statistical weights were ascribed to the determined rotation velocities of LTRs, according to the number of tracing days. Measured changes of the rotation velocity during the solar activity cycle, as well as a north–south rotation asymmetry, are discussed. The results obtained with and without the statistical weights procedure are compared, and it was found that the statistical significance of the solar differential rotation parameters' changes is higher when the statistical weights procedure is applied. A selective application of the height correction on LTR's positions has not removed the cycle-related changes nor the north–south asymmetry of the solar rotation measured tracing LTRs. So, projection effects cannot explain these changes. The differential rotation of LTRs is more rigid than the differential rotation obtained tracing magnetic features and measuring Doppler shifts, which can be explained by the association rate of the LTRs' positions with rigidly rotating `pivot points'. The observed cycle-related changes and the north–south asymmetry of the rotation velocity of LTRs are consistent with the cycle-related changes and the north–south asymmetry of the association rate between LTRs and pivot points.
Similar content being viewed by others
References
Adams, W. M. and Tang, F.: 1977, Solar Phys. 55, 499.
Aini Kambry, M. and Nishikawa, J.: 1990, Solar Phys. 126, 89.
Balthasar, H. and Wöhl, H.: 1980, Astron. Astrophys. 92, 111.
Balthasar, H. and Wöhl, H.: 1983, Solar Phys. 88, 71.
Balthasar, H., Schüssler, M., and Wöhl, H.: 1982, Solar Phys. 76, 21.
Balthasar, H., Vázquez, M., and Wöhl, H.: 1986, Astron. Astrophys. 155, 87.
Brajša, R., Vršnak, B., Ruždjak, V., Schroll, A., Pohjolainen, S., Urpo, S., and Teräsranta, H.: 1991, Solar Phys. 133, 195.
Brajša, R., Ruždjak, V., Vršnak, B., Pohjolainen, S., Urpo, S., Schroll, A., and Wöhl, H.: 1997, Solar Phys. 171, 1 (Paper I).
Brajša, R., Ruždjak, V., Vršnak, B., Wöhl, H., Pohjolainen, S., and Urpo, S.: 1999a, Solar Phys. 184, 281 (Paper II).
Brajša, R., Ruždjak, V., Vršnak, B., Wöhl, H., Pohjolainen, S., and Urpo, S.: 1999b, in A. Antalová, H. Balthasar, and A. Kučera (eds.), JOSO Annual Report 1998, 156.
Bruzek, A.: 1961, Z. Astrophys. 51, 75.
Deng, Y., Wang, J., and Harvey, J.: 1999, Solar Phys. 186, 13.
Dezsö, L. and Kovács, A.: 1994, Solar Phys. 151, 385.
Dupree, A. K. and Henze, W.: 1972, Solar Phys. 27, 271.
Escaut-Soru, I., Martres, M. J., and Mouradian, Z.: 1984, C. R. Acad. Sci. Paris 299, 545.
Godoli, G., Mazzucconi, F., and Piergianni, I.: 1993, Solar Phys. 148, 195.
Godoli, G., Mazzucconi, F., and Piergianni, I.: 1998, Solar Phys. 181, 295.
Howard, R.: 1984, Ann. Rev. Astron. Astrophys. 22, 131.
Howard, R. F.: 1990, Solar Phys. 126, 299.
Howard, R. and Harvey, J.: 1970, Solar Phys. 12, 23.
Howard, R., Gilman, P. A., and Gilman, P. I.: 1984, Astrophys. J. 283, 373.
Howard, R. F., Harvey, J. W., and Forgach, S.: 1990, Solar Phys. 130, 295.
Javaraiah, J. and Gokhale, M. H.: 1997, Solar Phys. 170, 389.
Komm, R. W., Howard, R. F., and Harvey, J. W.: 1993, Solar Phys. 145, 1.
KÜveler, G. and Wöhl, H.: 1983, Astron. Astrophys. 123, 29.
Liu, S.-Y. and Kundu, M. R.: 1976, Solar Phys. 46, 15.
Lustig, G.: 1984, Die Sterne 60, 295.
Lustig, G. and Wöhl, H.: 1989, Astron. Astrophys. 218, 299.
Meunier, N., Nesme-Ribes, E., and Grosso, N.: 1997, Astron. Astrophys. 319, 673.
Mouradian, Z., Martres, M. J., Soru-Escaut, I. and Gestelyi, L.: 1987, Astron. Astrophys. 183, 129.
Pulkkinen, P. and Tuominen, I.: 1998, Astron. Astrophys. 332, 748.
Roša, D., Vršnak, B., Božić, H., Brajša, R., Ruždjak, V., Schroll, A., and Wöhl, H.: 1998, Solar Phys. 179, 237.
Scherrer, P. H., Wilcox, J. M., and Svalgaard, L.: 1980, Astrophys. J. 241, 811.
Schröter, E.-H.: 1985, Solar Phys. 100, 141.
Schröter, E.-H. and Wöhl, H.: 1975, Solar Phys. 42, 3.
Sivaraman, K. R., Gupta, S. S., and Howard, R. F.: 1993, Solar Phys. 146, 27.
Snodgrass, H. B.: 1983, Astrophys. J. 270, 288.
Snodgrass, H. B.: 1984, Solar Phys. 94, 13.
Snodgrass, H. B.: 1992, in K. L. Harvey (ed.), 'The Solar Cycle', 12th Sacramento Peak Summer Workshop, ASP Conf. Ser. 27, 205.
Snodgrass, H. B., Howard, R., and Webster, L.: 1984, Solar Phys. 90, 199.
Stix, M.: 1989, in G. Klare (ed.), Rev. Modern Astron. 2, 248.
Suzuki, M.: 1998, Solar Phys. 178, 259.
Ternullo, M.: 1990, Solar Phys. 127, 29.
Urpo, S., Pohjolainen, S., and Teräsranta, H.: 1992, Solar Observations at Metsähovi in January- June 1992, Helsinki University of Technology, Metsähovi Radio Research Station, Series A, Report 12.
Vršnak, B., Pohjolainen, S., Urpo, S., Teräsranta, H., Brajša, R., Ruždjak, V., Mouradian, Z., and Jurač, S.: 1992, Solar Phys. 137, 67.
Wöhl, H.: 1983, Solar Phys. 88, 65.
Wöhl, H.: 1990, in L. Dezső (ed.), 'The Dynamic Sun', 6th European Meeting on Solar Physics, Publ. Debrecen Obs. 7, 19.
Wöhl, H.: 1997, Hvar Obs. Bull. 21, 1.
Zappala, R. A. and Zuccarello, F.: 1991, Astron. Astrophys. 242, 480.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Brajša, R., Ruždjak, V., Vršnak, B. et al. Statistical Weights and Selective Height Corrections in the Determination of the Solar Rotation Velocity. Solar Physics 196, 279–297 (2000). https://doi.org/10.1023/A:1005211625336
Issue Date:
DOI: https://doi.org/10.1023/A:1005211625336