The SOI-MDI high-latitude jet: the evidence for and against

Abstract

The apparent detection of a prograde jet at latitude 75° and at a radius of about 0.95R_⊙ in some inversions of rotation data from SOI--MDI (Schou et al., 1998) has excited considerable interest, but whether the jet really exists in the solar interior is certainly not yet firmly established. The detection of the feature is sensitive both to the inversion techniques used and to the methods of mode parameter estimation used to generate the input data. In particular, the feature is much more apparent in Regularized Least-Squares inversions than in inversions using an Optimally Localized Average approach, and is not detected at all in the present GONG data when analysed with the GONG peakfinding algorithm, or indeed in SOI data when analysed with the GONG algorithm. Therefore in this poster we examine critically the current evidence for the source and existence of this jet in the light of forward and inverse analyses.