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Relation between the 100-hPa Heat Flux and Stratospheric Potential Vorticity YVONNE B. L. HINSSEN

Summary: Relation between the 100-hPa Heat Flux and Stratospheric Potential Vorticity
Institute for Marine and Atmospheric Research Utrecht, Utrecht, Netherlands
Department of Meteorology, University of Reading, Reading, United Kingdom
(Manuscript received 31 May 2010, in final form 12 August 2010)
It is shown that a quantitative relation exists between the stratospheric polar cap potential vorticity and the
100-hPa eddy heat flux. A difference in potential vorticity between years is found to be linearly related to
the flux difference integrated over time, taking into account a decrease in relaxation time scale with height in
the atmosphere.
This relation (the PV­flux relation) is then applied to the 100-hPa flux difference between 2008/09 and the
climatology (1989­2008) to obtain a prediction of the polar cap potential vorticity difference between the
2008/09 winter and the climatology. A prediction of the 2008/09 polar cap potential vorticity is obtained by
adding this potential vorticity difference to the climatological potential vorticity. The observed polar cap
potential vorticity for 2008/09 shows a large and abrupt change in the potential vorticity in midwinter, related
to the occurrence of a major sudden stratospheric warming in January 2009; this is also captured by the
potential vorticity predicted from the 100-hPa flux and the PV­flux relation.
The results of the mean PV­flux relation show that, on average, about 50% of the interannual variability in
the state of the Northern Hemisphere stratosphere is determined by the variations in the 100-hPa heat flux.


Source: Ambaum, Maarten - Department of Meteorology, University of Reading


Collections: Geosciences