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

## [4.12] Optimal masks for g-mode detection in MDI velocity data

R. Wachter (Physikalisch Meteorologisches Observatorium Davos), J. Schou, A. Kosovichev, P. H. Scherrer (Hansen Experimental Physics Laboratory, Stanford University), Phoebus Team

We are applying spatial masks for MDI velocity data that are optimized for revealing g-modes in the frequency range 50 through 500 \muHz. These masks take into account the horizontal component of g-mode velocity eigenfunctions as well as the time dependent mode projection properties due to the changing solar B angle, and the varying noise level across the solar disk.

The solar noise, which is likely to be caused by supergranulation in this frequency range is assumed to be uniformly distributed over the solar surface, consisting of a dominant horizontal component and a smaller radial component. The optimal masks are applied to the image and the resulting time series are examined for possible g-mode candidates. Because no mode peak has been detected, firm upper limits for the surface visibility of individual low degree modes can be given.