Reply on RC2

Annika Drews

doi:10.5194/acp-2021-241-ac2

Abstract

Despite several studies on decadal-scale solar influence on climate, a systematic detection of solar-induced signals at the surface and the Sun's contribution to decadal climate predictability is still missing. Here, we disentangle the solar-cycle-induced climate response from internal variability and from other external forcings such as greenhouse gases. We utilize two 10-member ensemble simulations with a state-of-the-art chemistry climate model, to date a unique data set in chemistry climate modelling. We quantify the potential predictability related to the solar cycle and demonstrate that the detectability of the solar influence on surface climate depends on the magnitude of the solar cycle. Further, we show that a strong solar cycle forcing organizes and synchronizes the decadal-scale component of the North Atlantic Oscillation, the dominant mode of climate variability in the North Atlantic region.

Highlights

Since the middle of the last century long-term changes in global climate have been dominated by anthropogenic greenhouse gas emissions
We demonstrate that the strength of the solar surface signal depends on the amplitude of the solar cycle
We show that a stronger solar cycle signal induces a surface response that resembles the North Atlantic Oscillation (NAO)

Summary

Introduction

Since the middle of the last century long-term changes in global climate have been dominated by anthropogenic greenhouse gas emissions. We utilize a unique set of two 10-member ensemble simulations of a state-of-the-art coupled chemistry climate model to isolate and decipher the 11-year solar cycle's footprint in North Atlantic surface climate variability and to quantify the contribution 40 of the solar cycle to regional decadal potential predictability relative to other external forcings and internal variability during Northern Hemisphere winter. Our results agree qualitatively well with previous studies showing (i) low potential predictability due to external forcings and large internal variability over the extratropical North Atlantic (Boer et al, 2013), and (ii) statistically significant 70 surface signals associated with the solar cycle (Gray et al, 2010, 2013; Kodera, 2003; Thiéblemont et al, 2015)

Discussion

Findings

Methods