Estimate of the Energy Flux from Time-Distance Analysis

Abstract

In this Letter we show that time-distance measurements in helioseismology can be used to estimate the energy flux on the solar surface. Nonreciprocity of travel time along the ray path and different parity properties of sound speed, flow velocity, and magnetic field allow one to obtain information on large-scale distribution of plasma flows and magnetic fields. Here we extend our analysis and show that the covariance of sum and difference of the reciprocal travel times is a measure of large-scale, ``climatological'' heat flux and that the covariance of sum and difference of their departures from the mean gives an estimate for the magnetic energy flux. Using the reciprocal travel times measured in north-south and west-east directions, one can estimate the latitude- and longitude-dependent energy fluxes. The possibility of estimating the ``eddy'' fluxes, the heat and magnetic energy transport provided by small-scale motions, is outlined.