The Seismic Correlation Signature of Moderate‐Scale Flow in the Sun

Abstract

Flows in the solar convection zone introduce correlation between distinct horizontal-wavevector and frequency components of wave motion in the Sun. We derive expressions for the linear sensitivity of helioseismic correlation data to subphotospheric supergranular-scale flow, for use in helioseismic inversions. The sensitivity calculations are based on a model of randomly excited p- and f-mode oscillations in a plane-parallel solar envelope with flows. Woodard described a simple inversion of helioseismic correlation data for depth- and time-independent supergranular flow. The sensitivity calculations presented in this paper generalize previous calculations to the case of a flow velocity that depends on depth and varies slowly with time. We describe a method of estimating the data sensitivity kernel from helioseismic observations. The observed and theoretical kernels agree to within ≈20%.