On the ambiguous nature of the 11 year solar cycle signal in upper stratospheric ozone

S S Dhomse,R P Damadeo,G W Mann,W Feng,J D Haigh,J M Zawodny,W T Ball,M P Chipperfield,R Hossaini

doi:10.1002/2016gl069958

Abstract

AbstractUp to now our understanding of the 11 year ozone solar cycle signal (SCS) in the upper stratosphere has been largely based on the Stratospheric Aerosol and Gas Experiment (SAGE) II (v6.2) data record, which indicated a large positive signal which could not be reproduced by models, calling into question our understanding of the chemistry of the upper stratosphere. Here we present an analysis of new v7.0 SAGE II data which shows a smaller upper stratosphere ozone SCS, due to a more realistic ozone‐temperature anticorrelation. New simulations from a state‐of‐art 3‐D chemical transport model show a small SCS in the upper stratosphere, which is in agreement with SAGE v7.0 data and the shorter Halogen Occultation Experiment and Microwave Limb Sounder records. However, despite these improvements in the SAGE II data, there are still large uncertainties in current observational and meteorological reanalysis data sets, so accurate quantification of the influence of solar flux variability on the climate system remains an open scientific question.

Highlights

Over the 11 year solar cycle, total solar irradiance (TSI) changes by less than 0.1%, flux changes of up to 100% occur in the ultraviolet (UV) region of the solar spectrum
Up to now our understanding of the 11 year ozone solar cycle signal (SCS) in the upper stratosphere has been largely based on the Stratospheric Aerosol and Gas Experiment (SAGE) II (v6.2) data record, which indicated a large positive signal which could not be reproduced by models, calling into question our understanding of the chemistry of the upper stratosphere
New simulations from a state-of-art 3-D chemical transport model show a small SCS in the upper stratosphere, which is in agreement with SAGE v7.0 data and the shorter Halogen Occultation Experiment and Microwave Limb Sounder records

Summary

Introduction

Over the 11 year solar cycle, total solar irradiance (TSI) changes by less than 0.1%, flux changes of up to 100% occur in the ultraviolet (UV) region of the solar spectrum. Fourth, modeling the effects of solar variability on climate is difficult due to large uncertainties in the solar flux measurements [e.g., Ermolli et al, 2013] Despite these difficulties, our present understanding of the SCS in stratospheric ozone is that it has a “doublepeak” structure with maxima in the tropical lower (~22 km) and upper stratosphere (~50 km) and a negligible SCS in the tropical middle stratosphere. Recent observations suggest that solar cycle 24 (2008 onward) has the smallest number of sunspots in the last 100 years (e.g., http://solarscience.msfc.nasa.gov/predict.shtml) Some studies such as Haigh et al [2010], Merkel et al [2011], and Swartz et al [2012] used earlier versions of SORCE solar fluxes in chemical models and produced a negative SCS in the upper stratosphere/lower mesosphere, which showed reasonable agreement with Microwave Limb Sounder (MLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER)-derived SCS in stratospheric ozone. A brief description of the satellite data is provided in the supporting information

Model Simulations

Ozone in the Upper Stratosphere

Ozone Solar Response

Summary and Conclusions