Steven M. Cavallo |
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Tropopause polar vortex (TPV) climatology
Using NCEP/NCAR reanalysis data for the years 1948-1999, a summary of the cyclonic TPV climatology is given below.
The definition of the tropopause used here is the 1.5 PVU surface. Vortices are identified and tracked using a vortex
tracking algorithm, described in Hakim and Canavan 2003. Only those vortices that have total lifetimes of at least 2 days
and at least 60% of their lifetimes are north of 65 degrees latitude are included in the statistics.
Regions where TPV cyclone tracks begin, **grow, **decay, and end |
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Density* |
Normalized density* |
| NCEP-NCAR Reanalysis 1948-1999 |
X |
X |
| NCEP-NCAR Reanalysis 1948-1999 (January) |
X |
X |
| NCEP-NCAR Reanalysis 1948-1999 (July) |
X |
X |
*Density refers to the total vortex count within a 5x15 degree latitude x longitude box divided by the cosine of latitude for each lat/lon pair on the map; Normalized density is the density divided by maximum density over the domain.
**Tropopause potential temperature amplitude is the absolute difference between tropopause potential temperature in the vortex core and the ambient environment (last closed contour).
Growth (decay) is the location where the maximum growth (decay) rate occurred, as measured by tropopause potential temperature amplitude.
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Further information: |
| Cavallo, S.M. and G.J. Hakim, 2008: Analysis and structure of a tropopause cyclone.
Monthly Weather Review, submitted. |
| Hakim, G.J. and A. K. Canavan, 2005: Observed Cyclone-Anticyclone Tropopause Asymmetries.
J. Atmos. Sci., 62 (1), 231-240. |
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