Nighttime Pc3 pulsations : MM100 and MAGDAS observations

Yagova, N. and Heilig, B. and Nosikova, N. and Pilipenko, V. and Yumoto, K. and Yoshikawa, A. (2015) Nighttime Pc3 pulsations : MM100 and MAGDAS observations. Annales Geophysicae. ISSN 0992-7689 (Submitted)

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Abstract

A poorly known type of ULF waves - nighttime Pc3 pulsations are analyzed on the ground from auroral to equatorial latitudes. These oscillations have turned out to be a typical nightside wave phenomenon at middle and equatorial geomagnetic latitudes. Nighttime Pc3s can be divided into two classes. Pc3 pulsations of the first class are the ”tails” of the LT distribution of morning Pc3 pulsations. They have the highest occurrence rate at pre-morning hours and at the same geomagnetic latitudes as typical dayside Pc3 pulsations. The night signatures of dayside Pc3 waves are observed during the periods of fast solar wind (> 600 km/s). The mechanism of this type of nighttime Pc3 pulsations is probably related to the refraction of a fast compressional wave incident on the dayside inner magnetosphere. The second type is the specific nighttime Pc3 pulsations. They are observed under moderate solar wind velocities and are localized at middle latitudes in the nightMLT sector. This type of nightside Pc3 pulsations is probably driven by a bursty magnetotail activity, similarly to quite-time Pi2 pulsations. The wave energy transfer from the magnetotail to the ground is to be performed via the fast magnetosonic wave. This conjecture is supported by high correlation of the occurrence rate of the specific nighttime Pc3s with the AE index of auroral activity.

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