**AAS 200th meeting, Albuquerque, NM, June 2002**

*Session 4. Helioseismology and the Solar Interior*

Display, Monday, June 3, 2002, 9:20am-6:30pm, SW Exhibit Hall
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## [4.04] Temporal Variation of Angular Momentum in the Solar Convection Zone

*R. Komm, R. Howe, B. Durney, F. Hill (NSO)*

We present the temporal variation of the solar angular
momentum derived from helioseismic observations. In the
absence of `true' angular momentum inversions, we use the
rotation rates resulting from rotation inversions of GONG
data and the density distribution from a model of the Sun.
We focus especially on the layers near the base of the
convection zone and the layers near the solar surface. We
derive the angular momentum as a function of depth and the
corresponding solid-body rotation. The angular momentum
decreases with increasing radius following essentially the
product of density times the fourth power of radius. The
tachocline can be identified as a local maximum in the
radial gradient of the angular momentum and as a local
maximum in the relative angular momentum after subtracting
the contribution of the solid-body rotation. The angular
momentum shows the strongest temporal variation near the
tachocline. This variation is reminiscent of the 1.3-yr
periodicity found in the equatorial rotation rate of the
tachocline, which is not too surprising since the angular
momentum of a spherical shell is heavily weighted toward the
equator. We discuss the extension of this variation into the
convection zone and into the radiative interior. In
addition, we fit the rotation rates as functions of latitude
with Legendre polynomials to cross-validate the numerical
results and to draw conclusions about the zonal flows
(`torsional oscillations') in the upper convection zone.

This work was supported by NASA Grant S-92698-F.

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Bulletin of the American Astronomical Society, **34**

© 2002. The American Astronomical Soceity.