Weather and Climate Systems

Simulated Changes in the Characteristics of Tropopause Polar Vorticies and Surface Cyclones Due To Arctic Sea Ice Loss

Dylan Lusk
OU School of Meteorology

26 March 2014, 3:00 PM

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

Substantial reductions of Arctic sea ice during the summer are leaving increasingly large areas of open water during the autumn and early winter. Greater amounts of heat and moisture have the potential to alter the unique conditions that enable Tropopause Polar Vortices (TPVs) to be maintained over the Arctic by reducing their radiative intensification mechanism. Since TPVs are important dynamical predecessors to surface cyclones, changes in their characteristics due to changing sea ice may be a key to understanding changes to surface low locations and intensity in the future. Here I present two high resolution numerically simulated climatologies to examine the impact of reducing sea ice on TPV characteristics and the resulting effects on surface lows.
Results show a substantial change in TPV tracks over the time period; however, their most frequent location over Northern Canada remains largely unchanged. This result is consistent with the known characteristics of TPVs, as limited latent heating rates are essential for their maintenance. Changes in surface cyclone tracks are seen as a local response from different locations in which TPVs flow over low-level baroclinic zones rather than the advection of surface cyclones into the Arctic. In particular, baroclinic zones along the Arctic coastline due to the lack of sea ice promote an increase in frequency of surface cyclones and a decrease in lifetimes of TPVs. The increase of surface cyclones furthermore promotes an increase in precipitation throughout the Arctic.

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