  We have derived the temporal power spectra of the horizontal velocity of the
solar photosphere. The data sets for 14 quiet regions observed with the Gband
filter of Hinode/SOT are analyzed to measure the temporal fluctuation of the
horizontal velocity by using the local correlation tracking (LCT) method. Among
the high resolution (~0.2") and seeing-free data sets of Hinode/SOT, we
selected the observations whose duration is longer than 70 minutes and cadence
is about 30 s. The so-called k-{\omega} diagrams of the photospheric horizontal
velocity are derived for the first time to investigate the temporal evolution
of convection. The power spectra derived from k-omega diagrams typically have a
double power law shape bent over at a frequency of 4.7 mHz. The power law index
in the high frequency range is -2.4 while the power law index in the low
frequency range is -0.6. The root mean square of the horizontal speed is about
1.1 km/s when we use a tracer size of 0.4" in LCT method. Autocorrelation
functions of intensity fluctuation, horizontal velocity, and its spatial
derivatives are also derived in order to measure the correlation time of the
stochastic photospheric motion. Since one of possible energy sources of the
coronal heating is the photospheric convection, the power spectra derived in
the present study will be of high value to quantitatively justify various
coronal heating models.
