Space and time analysis of the solar photospheric dynamics at moderate-l values

A space-time analysis of 36 days' worth of full-disk intensity and velocity images, obtained by the Global Oscillation Network Group, is used to produ ce a high-resolution e-v phase-difference spectrum for the spectral range ( 4 < l less than or equal to 2000, 0 less than or equal to v less than or eq ual to 8.3 mHz). This is the first time a phase-difference spectrum has bee n produced for intermediate-l values. The phase differences on the p-mode r idges are found to linearly increase from similar to 65 degrees at 2 mHz up to similar to 95 degrees at 4.7 mHz. Only near 3.9 mHz are the differences close to 90 degrees, the theoretically expected phase for adiabatic evanes cent waves. The phases between the ridges exhibit a steplike behavior in fr equency with negative values at low frequency and positive values (greater than 90 degrees) at high frequency. The negative phase values are consisten t with the extension to low- and moderate-l values of the plateau-interridg e regime discovered by Deubner et al. in 1990. However, positive phase valu es, which represent higher phase for the solar background than for the acou stic modes, were not expected. An understanding of this observed phase-diff erence behavior will improve our knowledge of the nature of the solar backg round and its interaction with the acoustic p-modes.