The global signal of the 11-year solar cycle in the stratosphere: observations and models

The global signal of the 11-year solar cycle in the stratosphere: observations and models Earlier studies used the data from four solar cycles, to examine the global structure of the signal of the 11-year sunspot cycle (SSC) in the stratosphere and troposphere, using correlations between the solar cycle and heights and temperatures at different pressure levels. Here, this work is expanded in Part I to show the differences of geopotential heights and temperatures between maxima and minima of the SSC. This study puts the earlier work on a firmer ground and gives quantitative values for comparisons with models. In Part II, two general circulation models (GCMs) with coupled stratospheric chemistry are used to simulate the impact of changes in solar output. This paper is not intended as a review of the whole topic of solar impacts, but provides some results recently obtained in observations and modelling. Comparisons between the GCM results and observations show that the differences between solar maximum and solar minimum for temperature and ozone are generally smaller than observed. In the middle and upper stratosphere, models are closer to agreeing with observations of temperature, but a significant observed temperature difference near 100 hPa is not reproduced in the models. Also, model predictions of the shape of the vertical profile of the ozone difference do not agree with observations and the comparisons are hindered by large statistical uncertainties in both models and observations. Nonetheless, the results are an improvement on 2-D model results in showing a larger ozone signal in the lower stratosphere. (C) 2002 Elsevier Science Ltd. All rights reserved.