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Title: A study of stratosphere-troposphere coupling with an aquaplanet model
Author: Cheung, Jacob Ching Ho
ISNI:       0000 0004 2723 7921
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2012
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The coupling between stratosphere and troposphere (ST) has been studied extensively using simple circulation models. It is known that the ozone-rich stratosphere interact with the troposphere through both radiative and dynamical processes. However, many of the models used in these studies only assume a slab ocean with a fixed sea surface temperature (SST) profile. To investigate the role of the ocean in the stratosphere-troposphere coupling, a fully coupled atmosphere-ocean model, FORTE (Fast Ocean Rapid Troposphere Experiment) is used in this study. In this project the Earth is modelled as a perfect sphere with its surface covered with water. In the first set of our experiments we introduce a perturbation to the stratosphere by increasing ozone concentration by a factor of five. In the second experiment we repeat the ozone perturbation experiment with a fixed SST profile such that the atmosphere-ocean coupling is shut off. Our results demonstrate that by including a dynamical ocean, the strength of the jet streams is less sensitive to stratospheric ozone perturbations whereas the extent of their latitudinal displacements is greater. Both of these are found to be a consequence of SST anomalies induced by ocean dynamics. On the other hand, our results show that in the presence of an interactive ocean, there is a general increase in tropospheric air temperature except for polar regions, while lacking the banded anomaly pattern observed in our fixed SST experiment and other ST coupling studies.
Supervisor: Czaja, Arnaud ; Haigh, Joanna Sponsor: Higher Education Funding Council for England
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral