ACRIM-gap and total solar irradiance revisited: Is there a secular trend between 1986 and 1996?

TL;DR

This study revisits the debate on secular trends in total solar irradiance between 1986 and 1996, using a magnetogram-based SATIRE model to bridge measurement gaps and compare with existing composites.

Contribution

It introduces a magnetogram-based SATIRE reconstruction to accurately fill TSI measurement gaps and reassesses the secular trend in TSI during the specified period.

Findings

The mixed ACRIM-SATIRE composite shows no TSI increase from 1986 to 1996.

The SATIRE-based reconstruction provides higher accuracy on short timescales.

No significant secular trend is observed in the revised TSI data.

Abstract

A gap in the total solar irradiance (TSI) measurements between ACRIM-1 and ACRIM-2 led to the ongoing debate on the presence or not of a secular trend between the minima preceding cycles 22 (in 1986) and 23 (1996). It was recently proposed to use the SATIRE model of solar irradiance variations to bridge this gap. When doing this, it is important to use the appropriate SATIRE-based reconstruction, which we do here, employing a reconstruction based on magnetograms. The accuracy of this model on months to years timescales is significantly higher than that of a model developed for long-term reconstructions used by the ACRIM team for such an analysis. The constructed `mixed' ACRIM - SATIRE composite shows no increase in the TSI from 1986 to 1996, in contrast to the ACRIM TSI composite.