  Recently, Karoff and Kjeldsen (2008) presented evidence of strong correlation
between the energy in the high-frequency part (5.3<\nu<8.3 mHz) of the acoustic
spectrum of the Sun and the solar X-ray flux. They have used disk-integrated
intensity observations of the Sun obtained from the VIRGO (Variability of solar
IRradiance and Gravity Oscillations) instrument on board SOHO (Solar and
Heliospheric Observatory) spacecraft. Similar signature of flares in velocity
observations has not been confirmed till now. The study of low-degree
high-frequency waves in the Sun is important for our understanding of the
dynamics of the deeper solar layers. In this paper, we present the analysis of
the velocity observations of the Sun obtained from the MDI (Michelson and
Doppler Imager) and the GOLF (Global Oscillations at Low Frequencies)
instruments on board SOHO for some major flare events of the solar cycle 23.
Application of wavelet techniques to the time series of disk-integrated
velocity signals from the solar surface using the full-disk Dopplergrams
obtained from the MDI clearly indicates that there is enhancement of
high-frequency global waves in the Sun during the flares. This signature of
flares is also visible in the Fourier Power Spectrum of these velocity
oscillations. On the other hand, the analysis of disk-integrated velocity
observations obtained from the GOLF shows only marginal evidence of effects of
flares on high-frequency oscillations.
