@article{oai:nipr.repo.nii.ac.jp:00004101,
 author = {Nagano, Hiroshi and Sato, Natsuo and Ayukawa, Masaru},
 journal = {Proceedings of the NIPR Symposium on Upper Atmosphere Physics},
 month = {Jun},
 note = {P(論文), In the cosmic radio noise absorption (CNA) data obtained by a riometer at Syowa Station, CNA pulsations were sometimes observed following geomagnetic sudden commencements (SC's). In order to investigate characteristics of the occurrence, 138 SC events were analyzed using 1-second CNA and geomagnetic data at Syowa Station from April 1981 to December 1986. Local time dependence can be seen in the SC-associated CNA pulsation (CNA Psc). The occurrence rate is highest in the morning and has a secondary peak before midnight, that is to say, it shows a marked dawn-dusk asymmetry. CNA Psc accompanies geomagnetic Psc at the time of strong CNA increase caused by large SC's with high pre-SC AE index. Furthermore, CNA Psc tends to be more correlated with the H component of magnetic Psc in the Psc 5 period range and the D component for shorter period in the Psc 4 range.},
 pages = {42--50},
 title = {CNA pulsations associated with geomagnetic sudden commencements},
 volume = {4},
 year = {1991}
}