A puzzling feature of the Earth’s equatorial upper atmosphere is the occurrence of enhanced VHF radar echoes near 150-km altitude. These so-called 150-km echoes have been observed for over 50-years, and occur nearly every day, making them a persistent feature of the equatorial ionosphere.

Subauroral polarization stream (SAPS) are latitudinally narrow flow channels of large westward plasma drifts in the subauroral ionosphere.

One of the most robust features of the solar magnetic cycle is that the stronger cycles rise faster than the weaker ones. This is popularly known as the Waldmeier Effect, which is known for more than 100 years.

The magnetic field in the corona is important for understanding solar activity. Linear polarization measurements inforbidden lines in the visible/IR provide information about coronal magnetic direction and topology.

Three hundred years ago, the Sun began to wake up. For 70 years—from about 1645 to 1715—the Sun had been eerily quiet, with very few sunspots erupting on its surface.

Earthquake and tsunami are known to be the source of atmospheric gravity waves that can generate plasma ripples in the space. On March 11, 2011, a magnitude 9.0 earthquake occurred near the east coast of Honshu, Japan, unleashing a savage tsunami to strike offshore of Japan.

Deriving the strength and direction of the three-dimensional (3D) magnetic field in the solar atmosphere is fundamental for understanding its dynamics. Volume information on the magnetic field mostly relies on photospheric and/or chromospheric surface vector magnetic fields.