Pi2 pulsation simultaneously observed in the E and F region ionosphere with the SuperDARN Hokkaido radar. Issue 5 (14th May 2014)

• Record Type: Journal Article
• Authors: Teramoto, M.; Nishitani, N.; Pilipenko, V.; Ogawa, T.; Shiokawa, K.; Nagatsuma, T.; Yoshikawa, A.; Baishev, D.; Murata, K. T.
• Is Part Of: Journal of geophysical research. Volume 119:Issue 5(2014:May)
• Page Start: 3444
• Page End: 3462
• Publication Date: 2014-05-14
• Subjects: Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2012JA018585
• Languages: English
• ISSNs: 2169-9380

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>We investigated Pi2 pulsations in the nightside ionosphere that began at 14:15 UT (2315 LT) on 11 July 2010, and they were observed with high‐temporal (8 s) resolution by beam 4 of the Super Dual Auroral Radar Network (SuperDARN) Hokkaido radar. These pulsations were simultaneously observed in both the ground/sea scatter echoes reflected from the <italic>F</italic> region height and in ionospheric echoes from field‐aligned irregularities in the sporadic <italic>E<sub>s</sub></italic> region. They had the same period of 110 s and approximately no phase lag. From the radar observations and the International Geomagnetic Reference Field model, the amplitude of the eastward (<italic>E</italic><sub>EW</sub>) component of the electric field of the Pi2 pulsations in the ionosphere was estimated ~8.0 mV/m in the <italic>F</italic> region and ~2.0 mV/m in the <italic>E</italic> region. Corresponding Pi2 pulsations appeared dominantly in the horizontal northward magnetic field component (<italic>H</italic>) at nearby ground stations, Moshiri (MSR), St. Paratunka (PTK), and Stecolny (STC), with amplitudes ranging from 6 nT (MSR) to 10 nT (STC). At the dominant frequency of 8.8 mHz, the coherences between <italic>H</italic> and <italic>E</italic><sub>EW</sub> were high (>0.9), the cross phases of <italic>E</italic><sub>EW</sub> relative to <italic>H</italic> were −56° and −45°, and the amplitude ratios were 2.7 × 10<sup>5</sup> m/s and 8.4 × 10<sup>5</sup> m/s, in the <italic>E</italic> and <italic>F</italic> regions, respectively. Based on a comparison of these results with theoretical predictions, we suggest that the concept of a pure cavity mode is not sufficient to explain the combined observations for midlatitude Pi2 waves and that the contribution of an Alfvén waves must be taken in account.</p> </abstract>