  Solar five-minute oscillations have been detected in the power spectra of two
six-day time intervals from soft X-ray measurements of the Sun observed as a
star using the Extreme Ultraviolet Spectrophotometer (ESP) onboard the Solar
Dynamics Observatory (SDO) Extreme Ultraviolet Variability Experiment (EVE).
The frequencies of the largest amplitude peaks were found matching within 3.7
microHz the known low-degree (l = 0--3) modes of global acoustic oscillations,
and can be explained by a leakage of the global modes into the corona. Due to
strong variability of the solar atmosphere between the photosphere and the
corona the frequencies and amplitudes of the coronal oscillations are likely to
vary with time. We investigate the variations in the power spectra for
individual days and their association with changes of solar activity, e.g. with
the mean level of the EUV irradiance, and its short-term variations due to
evolving active regions. Our analysis of samples of one-day oscillation power
spectra for a 49-day period of low and intermediate solar activity showed
little correlation with the mean EUV irradiance and the short-term variability
of the irradiance. We suggest that some other changes in the solar atmosphere,
e.g. magnetic fields and/or inter-network configuration may affect the mode
leakage to the corona.
