@article{oai:nipr.repo.nii.ac.jp:00002183,
 author = {Krishnaswamy,S. and Rosenberg,T.J.},
 journal = {Memoirs of National Institute of Polar Research. Special issue},
 month = {Aug},
 note = {P(論文), Long-period (Pc 4-5) modulations of ionospheric cosmic noise absorption (CNA) at Siple, Antarctica (L=4.2) are rarely seen unaccompanied by pulsations in the local geomagnetic field. Conjugate modulations of ∿2min period lasting about one hour were recorded near local noon by riometers at Siple and Roberval on October 30,1983. The Siple magnetometer records show little evidence of pulsations at this time. The absence of a ground magnetic signature implies that if such events are caused by ULF hydromagnetic waves (e. g., a field line resonance), the waves are highly localized and effectively screened by the ionosphere. In addition, the possible existence of a recurrent particle precipitation structure in space was suggested by observations of absorption modulations with periods of 10-15min which occurred on several days at about the same time of day. These modulations were also generally unaccompanied by magnetic pulsations.},
 pages = {171--182},
 title = {Modulated ionospheric absorption unaccompanied by significant geomagnetic pulsations},
 volume = {48},
 year = {1987}
}