Weather and Climate Systems

On TPV Thinking: an Object-based Approach

Nick Szapiro
OU School of Meteorology

08 April 2015, 3:00 PM

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

Tropopause polar vortices (TPVs) are common, coherent features with origins over polar regions and clear manifestations on the dynamic tropopause. This seminar will build a case for associating these upper level features with distinct effects on the thermodynamic, mass, and momentum budgets of Arctic sea ice. After some background on IPV, EPV, and TPV thinking, there will be two parts: tracking and composites.

To define a TPV objectively, a novel tracking algorithm is presented where TPVs are (1) segmented in space through a modified watershed approach, (2) corresponded between neighboring times through horizontal and vertical overlap, and (3) tracked over time by connecting major correspondences. Motivation, examples, sensitivities, and evaluation of the approach are discussed, with some possible extensions too.

These TPVs are then used as objects for composites in ERA-Interim, focusing on the summers of 2006 and 2007 as the period of interest. First, we derive characteristics of TPVs. Questions to address include: what are temperature, winds, water vapor, clouds, and ozone like in a TPV? Are cold- and warm-core TPVs opposites? Can a transient TPV generate a seasonal signal? Then, we consider the surface forcings associated with being under a TPV, including the response of Arctic sea ice to those forcings.

Finally, these diagnostic properties, forcings, and responses are used to motivate ongoing and future atmosphere-land and atmosphere-land-ocean-sea ice experiments using MPAS and CESM.

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