Short-Term Orbital Forcing: A Quasi-Review and a Reappraisal of Realistic Boundary Conditions for Climate Modeling

TL;DR

This paper provides an updated, precise set of Earth's astro-climatic parameters for Short-Term Orbital Forcing, highlighting the importance of accurate insolation calculations for climate modeling over the Holocene and future periods.

Contribution

It introduces a new pragmatic tool/database with the latest astronomical models, and addresses errors in daily insolation calculations that impact climate boundary conditions.

Findings

No systematic discrepancies with previous long-term orbital forcing databases.

Rich dynamical modulation of STOF on annual-to-decadal timescales.

Identified up to ±5% errors in daily insolation calculations due to orbital longitude tabulation.

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 1 kyr 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 {\it at noon}. We found important relative differences up to $\pm$ 5\%, which correspond to errors of 2.5 W m$^{-2}$ 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.