On the multispacecraft determination of periodic surface wave phase speeds and wavelengths

FOULLON, C.; FARRUGIA, C. J.; FAZAKERLEY, A. N.; OWEN, C. J.; GRATTON, F. T.; TORBERT, R.

JOURNAL OF GEOPHYSICAL RESEARCH

AMER GEOPHYSICAL UNION

Lugar: Washington, D.C.; Año: 2010 vol. 115 p. 1 - 8

0148-0227

Observations of surface waves on the magnetopause indicate a wide range of phase velocities and wavelengths. Their multispacecraft analysis allows a more precise determination of wave characteristics than ever before and reveal shortcomings of approximations to the phase speed that take a predetermined fraction of the magnetosheath speed or the average flow velocity in the boundary layer. We show that time lags between two or more spacecraft can give a qualitative upper estimate, and we confirm the unreliability of flow approximations often used by analyzing a few cases. Using two-point distant magnetic field observations and spectral analysis of the tailward magnetic field component, we propose an alternative method to estimate the wavelength and phase speed at a single spacecraft from a statistical fit to the data at the other site.