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Title: Stratospheric temperature trends
Author: Rumbold, Steven T.
ISNI:       0000 0004 2671 9582
Awarding Body: The University of Reading
Current Institution: University of Reading
Date of Award: 2007
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The stratospheric temperature trend has only been measurable on a global scale since the late 1970's during the satellite era. In the global annual mean, the stratosphere demonstrates a cooling over this time. This cooling is much greater than the warming at the Earth's surface and is therefore an important signature of climate change. Although models agree with the observations in terms of the sign of the temperature trend, there is inconsistency in the magnitude. In addition to the overall trend, the stratospheric temperatures demonstrate many scales of variability. One possible cause of this variability is the change in flux from the Sun over the 11-year solar cycle. By use of realistic solar cycle flux perturbations, the solar maximum minus minimum annual mean result displays a peak response at the stratopause with a magnitude of 1.6 K, an equatorial middle stratosphere minimum and a second peak in the lower stratosphere. This is in agreement with a previous multiple regression analysis of the ERA-40 temperatures The result of this study appears different to a multiple regression of the solar cycle in satellite observations alone; however, when the results are degraded to the resolution of the satellite channels, the results are more similar and thus the broad weighting functions axe a large contributor to the discrepancy. The same modelling techniques are used to evaluate the temperature change associated with anthropogenic-induced carbon dioxide and ozone changes. A first order time-varying response is established and then weighted to each of the satellite channels. When compared to the observations, it is found that the addition of the solar cycle reduces the discrepancy compared to neglecting the solar response in most satellite channels. Additionally, the associated radiative forcings across the tropopause are also calculated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available