DETERMINATION OF THE FULL VELOCITY VECTOR BASED ON VECTOR MAGNETOGRAPH MEASUREMENTS IN AN ASYMMETRIC SUNSPOT

A new method to determine the distribution of the full velocity vector in an asymmetric sunspot is presented. Measurements of the Doppler ve locity and of the vector of the magnetic field are used as initial dat a for these calculations, The determination is subdivided into two sta ges: in a first step we obtain the distribution of the velocity projec tion onto the solar surface, and in the second step the orthogonal com ponent of the velocity field is calculated. The method has been applie d to a sunspot observed from two observatories over 7 days, that is at different positions on the solar disk and in different phases of its development. The resulting vector velocity field is in good agreement with the basic features of the siphon flow model of penumbral flux tub es. The velocities are directed outwards from the sunspot, and they ha ve small values in the umbra and maximum values in the central part of the penumbra, while in the outer penumbra the velocities decrease rap idly. The vertical velocities are mainly localized at the umbral bound ary (upflows) and at the outer parts of the penumbra (downflows).