Short-term orbital forcing: A quasi-review and a reappraisal of realistic boundary conditions for climate modeling

Abstract

The aim of this paper is to provide geoscientists with the most accurate set of the Earth's astro-climatic parameters and daily insolation quantities, able to describe the Short-Term Orbital Forcing (STOF) as represented by the ever-changing incoming solar radiation. We provide an updated review and a pragmatic tool/database using the latest astronomical models and orbital ephemeris, for the entire Holocene and 1kyr into the future. Our results are compared with the most important database produced for studying long-term orbital forcing showing no systematic discrepancies over the full thirteen thousand years period studied. Our detailed analysis of the periods present in STOF, as perturbed by Solar System bodies, yields a very rich dynamical modulation on annual-to-decadal timescales when compared to previous results. In addition, we addressed, for the first time, the error committed considering daily insolation as a continuous function of orbital longitudes with respect to the nominal values, i.e., calculating the corresponding daily insolation with orbital longitudes tabulated at noon. We found important relative differences up to ± 5%, which correspond to errors of 2.5Wm−2 in the daily mean insolation, for exactly the same calendar day and set of astro-climatic parameters. This previously unrecognized error could have a significant impact in both the initial and boundary conditions for any climate modeling experiment.