The Global Oscillation Network Group (GONG) Project.

Helioseismology requires nearly continuous observations of the oscillations of the solar surface for long periods of time in order to obtain precise measurements of the sun's normal modes of oscillation. The GONG project acquires velocity images from a network of six identical instruments distributed around the world. The GONG network began full operation in October 1995.

Volcanic dust and meteor rates.

A worldwide increase in radar mleteor echo rates in 1963 correlates with the injection of massive quantities of volcanic dust into the upper atmosphere by the explosion of Mount Agung in Bali in March 1963. The consequent change in atmospheric radiative heating most probably produced the increase by changing the air density gradient.