Very long lived wave patterns detected in the solar surface velocity signal

The wavelike pattern of velocity variations in the outer layers of the Sun known as the "torsional oscillations" is shown to consist of long-lived ine rtial oscillation waves. The dominant pattern which was first identified at Mount Wilson and which has now been observed with the Michelson Doppler Im ager instrument and the Global Oscillation Network Group, may be the m=0 co mponent of a hierarchy of inertial oscillation waves having m-values up to 8. The identification is based on the geometric structure and the relations hip of the pattern in adjacent bands of latitude. It is found that the cros s-correlation between adjacent latitude bands consists almost exclusively o f an oscillatory component with little or no evidence of a peak at 0 lag. S ince the pattern has a global extent in the longitudinal direction with the wave pattern being coherent over essentially the whole solar circumference , a convective interpretation cannot be supported when the latitudinal stru cture is limited to less than 3 degrees of latitude. These wavelike pattern s define a rotation rate which is similar to that found for the magnetic fe atures but which deviates in zones with magnetic activity in the sense that the m=1 component rotates more slowly while the m=3 and 4 components rotat e more rapidly.