  The high temporal, spatial and spectral resolution of Interface Region
Imaging Spectrograph (IRIS) has provided new insights into the understanding of
different small-scale processes occurring at the chromospheric and transition
region (TR) heights. We study the dynamics of high-frequency oscillations of
active region (AR 2376) moss as recorded by simultaneous imaging and spectral
data of IRIS. Wavelet transformation, power maps generated from slit-jaw images
in the Si IV 1400\AA passband, and sit-and-stare spectroscopic observations of
the Si IV 1403\AA spectral line reveal the presence of high-frequency
oscillations with $\sim$1-2 minute periods in the bright moss regions. The
presence of such low periodicities is further confirmed by intrinsic mode
functions (IMFs) as obtained by the empirical mode decomposition (EMD)
technique. We find evidence of the presence of slow waves and reconnection-like
events, and together they cause the high-frequency oscillations in the bright
moss regions.
