2004b: Modeling the ENSO modulation of Antarctic climate in the late 1990s with Polar MM5

The Polar fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) is employed to examine the El Niño–Southern Oscillation (ENSO) modulation of Antarctic climate for July 1996–June 1999, which is shown to be stronger than for the mean modulation from 1979 to 1999 and appears to be...

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Bibliographic Details
Main Authors: David H. Bromwich, Andrew J. Monaghan, Zhichang Guo
Other Authors: The Pennsylvania State University CiteSeerX Archives
Format: Text
Language:English
Subjects:
Antarctic
Byrd
Filchner Ice Shelf
Marie Byrd Land
Pacific
Ross Ice Shelf
Weddell
Weddell Sea
Antarc*
Ice Shelf
Online Access:http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.496.3444
http://polarmet.osu.edu/PolarMet/PMGFulldocs/bromwich_monaghan_jc_2004.pdf
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Summary:The Polar fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) is employed to examine the El Niño–Southern Oscillation (ENSO) modulation of Antarctic climate for July 1996–June 1999, which is shown to be stronger than for the mean modulation from 1979 to 1999 and appears to be largely due to an eastward shift and enhancement of convection in the tropical Pacific Ocean. This study provides a more comprehensive assessment than can be achieved with observational datasets by using a regional atmospheric model adapted for high-latitude applications (Polar MM5). The most pronounced ENSO response is observed over the Ross Ice Shelf–Marie Byrd Land and over the Weddell Sea–Ronne/Filchner Ice Shelf. In addition to having the largest climate variability associated with ENSO, these two regions exhibit anomalies of opposite sign throughout the study period, which supports and extends similar findings by other investigators. The dipole structure is observed in surface temperature, meridional winds, cloud fraction, and precipitation. The ENSO-related variability is primarily controlled by the large-scale circulation anomalies surrounding the continent, which are consistent throughout the troposphere. When comparing the El Niño/La Niña phases of this late 1990s ENSO cycle, the circulation anomalies are nearly mirror images over the entire Antarctic, indicating their significant modulation by ENSO. Large temperature anomalies, especially in autumn, are prominent over the

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