@article{f23987cfda0f47ecafa8f7f9c5d65a2c,
title = "Tri-phonic helioseismology: Comparison of solar p modes observed by the helioseismology instruments aboard SOHO",
abstract = "The three helioseismology instruments aboard SOHO observe solar p modes in velocity (GOLF and MDI) and in intensity (VIRGO and MDI). Time series of two months duration are compared and confirm that the instruments indeed observe the same Sun to a high degree of precision. Power spectra of 108 days are compared showing systematic differences between mode frequencies measured in intensity and in velocity. Data coverage exceeds 97% for all the instruments during this interval. The weighted mean differences (V - I) are -0.1 μHz for l = 0, and -0.16 μHz for l = 1. The source of this systematic difference may be due to an asymmetry effect that is stronger for modes seen in intensity. Wavelet analysis is also used to compare the shape of the forcing functions. In these data sets nearly all of the variations in mode amplitude are of solar origin. Some implications for structure inversions are discussed.",
author = "T. Toutain and T. Appourchaux and F. Baudin and C. Fr{\"o}hlich and A. Gabriel and P. Scherrer and Andersen, {B. N.} and R. Bogart and R. Bush and W. Finsterle and Garc{\'i}a, {R. A.} and G. Grec and Henney, {C. J.} and Hoeksema, {J. T.} and A. Jim{\'e}nez and A. Kosovichev and {Roca Cort{\'e}s}, T. and S. Turck-Chi{\`e}ze and R. Ulrich and C. Wehrli",
note = "Funding Information: VIRGO is a cooperative effort of many individual scientists and engineers at several institutes in Europe and U.S.A. The VIRGO team has been supported by several national and international funding agencies which are gratefully acknowledged: the PMOD/WRC by the Swiss National Science Foundation and PRODEX, the IRMB by the Fonds de la Recherche Fondamentale Collection d{\textquoteright}initiative min-ist{\'e}rielle and PRODEX, the SSD/ESA by their annual funds from the Science Directorate, the IAC by the CICYT through PNIE, and the OCA by the CNES and CNRS. Funding Information: All three instruments benefit from the quiet and well run SOHO platform built by Matra-Marconi Space. SOHO is an international collaboration programme of the European Space Agency and the National Aeronautics Space Administration. F.B. and the SOI/MDI Team at Stanford acknowledge support from NASA under Contract NAS 5–30386.",
year = "1997",
doi = "10.1023/A:1004949832159",
language = "English (US)",
volume = "175",
pages = "311--328",
journal = "Solar Physics",
issn = "0038-0938",
publisher = "Springer Netherlands",
number = "2",
}