Power spectra (averaged over azimuth of wavevector k and 336 datasets) of TD travel-time maps, and LCT div_h and ω_z maps computed from HMI Dopplergrams and intensity images at the solar equator near disk center (distributed symmetrically between 7° east and west of the central meridian). a) Divergence-sensitive travel times τ^oi for f modes and p₁ modes as well as LCT div_h. b) Vorticity-sensitive travel times τ^ac for f modes and p₁ modes as well as LCT ω_z. The amplitudes of LCT div_h and ω_z power were rescaled to match the range of the travel-time power. The dashed lines represent noise models for the f and p₁ modes based on Gizon & Birch (2004). The thickness of the lines denotes the 1σ error.