Orbital signals in the diurnal cycle of radiation

Results of this study show: 1) at the solstices, a marked change in dominance from precession (for the solar elevation classes associated with early morming/late afternoon) to obliquity (for the elevation class containing solar noon) occurs in solar radiation; 2) at the equinoxes, cycles corresponding to those associated with eccentricity are evident in the radiation data at all individual time intervals of the day. These results imply that paleoclimatic proxy data displaying strong spectral peaks corresponding to eccentricity (100 kyr) and obliquity (41 kyr), such as records of global ice volume, may be related to radiation changes occurring in the solar elevation class containing solar noon, while paleoclimatic proxy data displaying strong spectral peaks corresponding to precession, for example, sea-surface temperatures, appear to be showing the dominance of precession on the daily total radiation. -from Author