Vertical Flow in Supergranules
Abstract
Measuring the vertical flow in supergranules is a long-standing and difficult problem. We have tried a new strategy that has met with some success, using Doppler maps from the Michelson Doppler Imager (MDI) on SOHO. From maps of the horizontal divergence signal measured from the time-distance helioseismology of f modes, cells are identified by local peaks in the divergence signal. The surface Doppler signal is then averaged about these cell locations, to obtain a mean Doppler signal. Averaging over many cells yields a statistically stable result. From simultaneous magnetograms, systematic effects associated with magnetic elements have been examined. An upward vertical flow in the center half of cells and a downward flow in the outer half are found, much as if the supergranules are simple convective structures.
- Publication:
-
AAS/Solar Physics Division Meeting #40
- Pub Date:
- May 2009
- Bibcode:
- 2009SPD....40.0931D