Results of a detailed study on supergranule lifetime and velocity fields are presented. We show the correlation between the observed downdraft velocity and the network magnetic flux elements on the quiet sun. After excluding areas with magnetic flux density ≥ 25 G, we find that the upper limit of the supergranule vertical speed is 0.1 km s-1 for both downdraft and updraft, and the r.m.s. speed is 0.03 km s-1. By observing the evolution of individual supergranules, we find that the average lifetime of supergranules might be ≥ 50 hours. We describe different ways of formation and decay of supergranular cells. New cells usually form in an area containing no pre-existing supergranule velocity fields. Cells may disappear in two ways: fragmentation and fading away.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science