The Study of the Changing Solar Interior Using Global and Local Helioseismology

LWS TR&T Grant NAG5-13538 E.Rhodes, USC

Studies of Internal Flow Measurements During Solar Cycle 22 With MWO 60-Foot Tower

Until now the sub-photospheric torsional oscillations and meridional flows have only been seen in helioseismic data beginning in 1995 with the first GONG data sets and these studies have been extended through 2004 using inversions of both GONG and MDI observations.

Due to the importance of these observations for solar dynamo studies, we are employing MWO observations from 1987-1995 to study the torsional oscillations and the meridional flows during Solar Cycle 22.

Studies of Internal Flow Measurements During Solar Cycle 22 With MWO 60-Foot Tower

As shown in the next slide, these observations began in 1987 and they comprise the only suitable set of daily observations of full-disk Dopplergams taken prior to 1995 with a temporal cadence and spatial resolution identical to that of MDI Dopplergrams.

To validate the utility of these data, we have compared maps of the solar torsional oscillations which we have computed from simultaneous MWO and MDI Dopplergrams. As shown in the last slide, the two maps are very similar and this similarity gives us confidence in the usefulness of the MWO data for these studies.

MWO 60-Foot Solar Tower Observing History in Solar Cycles 22 and 23

2002

1990

1994

1998

1987

1991

1995

1999

First Two108-day setsBased UponMWO DataOnly

First two108-day setsBased UponMDI Data Only