Damping and frequency reduction of the f-mode due to turbulent motion in the solar convection zone

Solar-f-mode properties were observed recently with high accuracy using hig h-resolution Michelson Doppler Imager (MDI) data from SOHO (Duvall et al. 1 998). According to these observations, linewidths increase with wavenumber k and the f-mode frequency omega is significantly lower than the frequency omega(0) given by the simple dispersion relation omega(0)(2) = gk. This pap er provides a possible explanation of these observations on the basis of th e turbulent flow that is in the convection zone. The f-mode spends more tim e propagating against the flow than with the how. As a result, its effectiv e speed and consequently frequency are reduced. This reduction is revealed by the real part of omega. A negative imaginary part of the frequency omega represents the damping of the coherent-f-mode field due to scattering by t he turbulent flow. The f-mode damping is a result of the generation of the turbulent field at the expense of the coherent field.