This study explores extreme surface temperature events in Southern Hemisphere winter (June – August) from 1979 to 2011 and
their relation with meridional mass circulation by using daily ERA-interim Re-Analysis data from European Center for Medium-Range Weather
Forecasts (ECMWF). Meridional mass circulation indices are developed to quantitatively represent the warm air mass being transported into
the polar region in the upper atmosphere and the cold air mass being transported out of the polar region in the lower atmosphere. Our
results show that weaker poleward warm air mass transport aloft is associated with weaker cold air transport toward equator in the lower
troposphere, resulting in cold air being confined in the polar regions. Similarly, stronger poleward warm air mass transport in the upper
atmosphere is related to stronger cold air transport out of the polar regions, causing enormous cold air outbreaks in the mid-latitude
regions. We find that regions to the south of 45S exhibit a robust relationship between surface air temperature anomalies and meridional
mass circulation. Weaker circulation is associated with abnormally cold in Antarctica and abnormally warm in regions from 45S to 60S.
Conversely, stronger circulation is related to anomalously warm in Antarctica and anomalously cold in the surrounding continental shelf,
particularly over Weddell-Scotia Sea and north Ross Sea where are the two preferred routes for cold air coming out of Antarctica. On the
other hand, temperature anomalies over the regions north of 45S are not sensitive to the meridional circulation variability. The fact that
surface air temperature anomalies over the Southern Ocean rarely exceed 4C suggests that cold air coming out of Antarctic has limited
impacts on the Southern Ocean due to its large thermal inertia. In summary, the meridional mass circulation indices provide a robust
diagnostics for extreme cold events in 45S - 90S domain very well, but may not be adequate to describe all cold events over the vast
mid-latitude regions in the Southern Hemisphere. / A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment
of the requirements for the degree of Master of Science. / Spring Semester 2016. / April 13, 2016. / cold air outbreak, extreme temperature events, meridional mass circulation, southern hemisphere / Includes bibliographical references. / Ming Cai, Professor Directing Thesis; Jeffrey M. Chagnon, Committee Member; Guosheng Liu,
Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_360487 |
| Contributors | Yan, Ruikai (authoraut), Cai, Ming (professor directing thesis), Chagnon, Jeffrey M. (committee member), Liu, Guosheng (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Earth, Ocean, and Atmospheric Science (degree granting department) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource (47 pages), computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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