INTERMEDIATE DEGREE P-MODE FREQUENCY SPLITTINGS NEAR SOLAR MAXIMUM

We report on observations of global solar Ca K-line intensity oscillat ions taken in May 1991 from Mees Solar Observatory, Hawaii. We measure p-mode frequency splittings for modes of spherical harmonic degrees b etween 20 and 129 averaged over the radial order of the modes. Our mea surement of the antisymmetric component of the splittings is comparabl e with previous measurements and thus indicates a decrease in the lati tudinal differential rotation with depth into the convection zone and the upper radiative zone. We find evidence for a 1% variation in the r otation rate of the upper convection zone roughly in phase with the so lar activity cycle. Our measurement of the symmetric component of the splittings is of the same order as was reported from the previous sola r maximum and is an order of magnitude larger than has been measured n ear solar minimum. From the degree dependence of the symmetric compone nt of the splittings, we find evidence for an aspherical fractional so und speed perturbation located at a depth of 0.85 +/- 0.05 solar radii . This perturbation has a magnitude of deltac/c almost-equal-to +9 x 1 0(-4) at the equator relative to the poles. Additionally, there is evi dence for a near-surface aspherical sound speed perturbation of smalle r magnitude deltac/c almost-equal-to +4 x 10(-4) at the equator relati ve to the poles. If an intense global magnetic field were the dominant source of the observed symmetric component of the splittings, instead of latitudinal gradients in the sound speed, then global fields of or der 10(5) G would be required in the convection zone.