Weather and Climate Systems

Towards Creating a Climatology of TPVs

Dylan Lusk
OU School of Meteorology

15 April 2015, 3:00 PM

National Weather Center, Room 5600
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK

Tropopause Polar Vortices, or TPVs, are long-lived, coherent vortices located primarily on the tropopause over polar regions. These upper level features have been identified as important dynamical predecessors to surface cyclogenesis for some time, yet only in the past decade have been recognized as a long-lived traceable feature, with lifetimes sometimes exceeding 2 months. With such long lifetimes, these features could have important implications for model predictability. Additionally, these features have been identified as playing a large role in many extreme weather events in the mid-latitudes. While past studies have focused on the structure and evolution of TPVs in polar regions, no studies have closely examined interactions at the mid-latitudes. As such, it would be useful to be able to examine TPVs in a climatological sense to better understand the conditions which may more commonly bring about mid-latitude interactions.

This seminar will begin with a summary of past TPV research, followed by a comparison of a new TPV tracking algorithm with one used in previous studies. Preliminary results from the new tracking algorithm on the ERA-Interim data set will be presented. TPVs are primarily located within the region west of Greenland over Baffin Bay, and show overall similar characteristics to a previous study performed on the NCEP-NCAR reanalysis data set. Several ideas for how to use the data set to further understand mid-latitude interactions will be discussed, including a closer investigation of the atmospheric effects of the Arctic Oscillation (AO) on TPVs. TPVs are found more frequently over the Arctic within the positive phase of the AO, with a clear signal of movement towards the mid-latitudes within the negative phase.

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