Energy distribution of solar oscillation modes inferred from space-based measurements

We have measured the energy distribution of solar p- and f-mode oscillation s of angular degree and temporal frequency in the range 100 < l < 800 and 2 < v(mHz) < 4 using helioseismology data from the Solar Oscillations Invest igation-Michelson Doppler Imager instrument on the Solar and Heliospheric O bservatory satellite. At temporal frequency v approximate to 3 mHz, the sur face velocity power per oscillation mode increases slightly with angular de gree between l = 100 and l = 2000 but decreases rather steeply with l above l = 200, in approximate agreement with earlier findings from ground-based measurements. From this we infer that the time-averaged energy per mode, wh ich is theoretically related to the modal surface velocity power, decreases steeply with, at fixed l frequency, over the entire observed l-range. Spec ifically, at v = 3.1 mHz, the energy per mode drops by a factor of approxim ate to 10 between l = 150 and l = 650, a circumstance not quantitatively un derstood at present.