Large-scale horizontal flows in the solar photosphere. I. Method and tests on synthetic data

Abstract

We propose a useful method for mapping large-scale velocity fields in the solar photosphere. It is based on the local

correlation tracking algorithm when tracing supergranules in full-disc dopplergrams. The method was developed using synthetic data.

The data are transformed during the data processing into a suitable coordinate system, the noise is removed, and finally the velocity field is

calculated. Resulting velocities are compared with the model velocities and the calibration is done. From our results it becomes clear that

this method could be applied to full-disc dopplergrams acquired by the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SoHO).