Comparison of GONG and MDI solar p-mode background

Abstract

Using Severino's model, we estimate the amount of coherent correlated and uncorrelated background and incoherent noise components needed to reproduce the following four helioseismic spectra: V power, I power, V-I phase difference and V-I coherence, using GONG and MDI data. We confirm that a coherent correlated component of 10-15% of the total background and noise is needed in both V and I and that a larger amount of coherent uncorrelated background is needed for MDI data compared to GONG data to compensate for a smaller incoherent noise.