Pi2 pulsation simultaneously observed in the <i>E</i> and <i>F</i> region ionosphere with the SuperDARN Hokkaido radar

<jats:title>Abstract</jats:title><jats: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 <jats:italic>F</jats:italic> region height and in ionospheric echoes from field‐aligned irregularities in the sporadic <jats:italic>E<jats:sub>s</jats:sub></jats: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 (<jats:italic>E</jats:italic><jats:sub>EW</jats:sub>) component of the electric field of the Pi2 pulsations in the ionosphere was estimated ~8.0 mV/m in the <jats:italic>F</jats:italic> region and ~2.0 mV/m in the <jats:italic>E</jats:italic> region. Corresponding Pi2 pulsations appeared dominantly in the horizontal northward magnetic field component (<jats:italic>H</jats: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 <jats:italic>H</jats:italic> and <jats:italic>E</jats:italic><jats:sub>EW</jats:sub> were high (>0.9), the cross phases of <jats:italic>E</jats:italic><jats:sub>EW</jats:sub> relative to <jats:italic>H</jats:italic> were −56° and −45°, and the amplitude ratios were 2.7 × 10<jats:sup>5</jats:sup> m/s and 8.4 × 10<jats:sup>5</jats:sup> m/s, in the <jats:italic>E</jats:italic> and <jats:italic>F</jats: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.</jats:p>