Imaging and Computing Seminar
Shravan Hanasoge, Geosciences, Princeton
Noise Tomography of the 3-D interior the Sun and Earth
Solar Oscillations, similar to Earth noise, are excited stochastically. Statistical averages of cross correlations of the surface velocity field of the Sun, observed at nearly 16 million points, show the presence of seismic signals, allowing us to measure wave travel times and amplitudes. I will describe techniques of PDE-constrained optimization that are applied to retrieve the gradient of the measurement misfit and show examples of sensitivity kernels. These developments render possible the accurate imaging of sub-surface magnetic fields and convection in the Sun and I will present recent work along these lines. Time permitting, I shall also show preliminary results pertaining to the localization of Earth-noise sources.