DIAGNOSTICS OF SUBSURFACE MAGNETIC FIELDS, MASS FLOWS AND THEIR SPATIAL GRADIENTS FROM TIME-DISTANCE ANALYSIS

M. Ryutova

In collaboration with the time-distance analysis team (Stanford) and the correlation tracking team (Lockheed)

A new method of obtaining the information on the subsurface plasma flows and magnetic fields using the the sine and cosine convolutions of measured propagation times will be extended for the reconstruction of the spatial inhomogeneities of subsurface magnetic fields and plasma flows. As it was shown the convolutions with respect to first harmonics contain an information on the direction and absolute value of the flow velocity, while second harmonics describe predominantly the orientation and absolute value of horizontal magnetic fields and the spatial gradients of plasma flow. Specifically, the sum of forward and backward propagation times (their second harmonics convolutions) allows to find the distribution of magnetic field. The second harmonic convolutions of the time difference gives the spatial distribution of the divergency of flow. The third harmonics are related to magnetic field inhomogeneities. We propose to use this technique to reconstruct the distribution of the magnetic fields and flows including the flow divergency at different depth corresponding to time-distance measurement taken for different annuli.

We will use this technique to reconstruct the distribution of the magnetic fields and flows including the maps of the divergence of flow. The reconstructed maps obtained for the different subsurface layers will be analyzed together with the surface maps obtained for the same day by the correlation tracking method developed by Lockheed group.

The reconstructed maps will be compared and analyzed with the magnetograms of subsequent days: the reconstructed maps show the concentration of magnetic field in some subsurface regions which have no counterparts on the visible surface, and which may be a source of the flux yet to be emerged.