  We study temperature $T$ and frequency $\omega$ dependence of the in-plane
fluctuation conductivity of a disordered superconducting film above the
critical temperature. Our calculation is based on the nonlinear sigma model
within the Keldysh technique. The fluctuation contributions of different
physical origin are found and analyzed in a wide frequency range. In the
low-frequency range, $\omega\ll T$, we reproduce the known leading terms and
find additional subleading ones in the Aslamazov-Larkin and the Maki-Thompson
contributions to the ac conductivity. We also calculate the density of states
ac correction. In the dc case these contributions logarithmically depend on the
Ginzburg-Landau rate and are considerably smaller that the leading ones.
However, in the ac case an external finite-frequency electromagnetic field
strongly suppresses the known Alsamazov-Larkin and Maki-Thompson ac
contributions, while the corresponding new terms and the density of states
contribution are weakly suppressed and therefore become relevant at finite
frequencies.
