Kevin Bowley

(Penn State, Dept. of Meteorology and Atmospheric Science, Assistant Teaching Professor)

Interpreting rapid increases of zonal available potential energy from a synoptic-scale perspective.

What Meteo Colloquium Graduate UG Homepage
When Aug 29, 2018
from 03:30 pm to 04:30 pm
Where John Cahir Auditorium 112 Walker Building
Contact Name David Stensrud
Contact email
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Kevin Bowley 2018 

Available potential energy (APE), a measure of the energy available for conversion to kinetic energy, has been previously applied to examine changes in baroclinic instability and seasonal changes in the general circulation. Here, pathways in which the troposphere can build the reservoir of zonal available potential energy (AZ) on synoptic (3–10 day) time scales are explored. A climatology of AZ and its generation (GZ) and conversion terms are calculated from the National Centers for Environmental Prediction–Department of Energy Reanalysis 2 dataset from 1979 to 2011 for 20°–85°N. Increases in GZ and reductions in baroclinic conversion (CA), source and sink terms for AZ, are shown to equally contribute toward increasing AZ in most seasons.  An examination of winter buildup periods in particular find that a diabatic enhancement of the meridional temperature gradient in the North Pacific jet exit region is a key factor toward increasing AZ.  One such pathway toward achieving this enhancement is anticyclonic wave breaking. 

To explore this further, an examination of a climatology of anticyclonic and cyclonic wave breaking (AWB and CWB, respectively) is performed for AZ buildups.  Widespread positive anomalies in AWB and negative anomalies in CWB are found for most AZ buildup periods and are attributed to a poleward-deflected jet.  Less frequent west-east dipoles in wave breaking anomalies are attributed to elongated and contracted jet streams over the North Atlantic and North Pacific basins. Finally, a rigorous analysis of long-duration AWB events for winter AZ buildup periods to an anomalously high AZ state are examined using a quasi-Lagrangian grid shifting technique. These results suggest the critical role of North Pacific AWB events in diabatically enhancing the North Pacific jet exit region (and increasing Northern Hemisphere AZ) through latent heating equatorward of the jet and radiative and evaporative cooling poleward of the jet.