Coronal mass ejections: 1979–1981

In an examination of the Solwind coronagraph images obtained during the interval March 28, 1979, to December 31, 1981, we have identified 998 coronal mass ejections and recorded their structural classes, central latitudes, latitudinal spans, speeds, excess brightnesses, and relative importances. A statistical analysis revealed the following general results. (1) The properties of coronal mass ejections (CMEs) depended strongly on their structure. Curved front, halo, and complex CMEs were the most energetic, and single spike, streamer blowout, and diffuse fan CMEs were the least energetic. CMEs occurred over a wide range of position angles, broadly centered on the equator, and had an average angular span of 45°. The leading edge moved at an average of approximately 470 km/s, and the average ejected mass and kinetic energy were 4.1×10 15 g and 3.5×10 30 erg, respectively. The average CME proton flux at the equator at 1 AU was 2.2×10 7 cm −2 s −1 or approximately 5% of the measured in situ flux during 1971–1976. (2) During 1979–1981, the average occurrence rate was 1.8/day for all CMEs, 0.9/day for “major” CMEs, and 0.15/day for all CMEs that crossed the equator and had an angular span of at least 45°. (3) The temporal variations in the CME occurrence rate did not show an obvious persistent relation to the variations in the sunspot number on time scales ranging from 7 to 180 days. During 1979–1981 the maximum in the 180‐day average CME rate peaked in the second half of 1980, whereas the 180‐day average sunspot number peaked during the first half of 1980. The 180‐day average rate of fast CMEs (speeds of at least 800 km/s) had a monotonic increase that seemed to be more closely associated with the occurrence rate of large solar flares than with the variation of the sunspot number.