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- Author or Editor: Lodovica Illari x
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Abstract
Dynamical features of the warm blocking anticyclone which persisted over Europe during the summer of 1976 are studied using National Meteorological Centre analyses. The dynamics am presented from the perspective of quasi-geostrophic potential vorticity q. The block is shown to be a region of anomalously low, almost uniform q¯. Computed balances in the 300 mb monthly mean quasi-geostrophic potential vorticity equation show that the mean flow advection v¯˙∇q¯ and the eddy forciv′˙∇q′ of q¯ are of comparable magnitude and have the tendency to balance one another. It is suggested that transfer by synoptic scale systems acts to maintain the q¯ anomaly against its advection downstream.
Abstract
Dynamical features of the warm blocking anticyclone which persisted over Europe during the summer of 1976 are studied using National Meteorological Centre analyses. The dynamics am presented from the perspective of quasi-geostrophic potential vorticity q. The block is shown to be a region of anomalously low, almost uniform q¯. Computed balances in the 300 mb monthly mean quasi-geostrophic potential vorticity equation show that the mean flow advection v¯˙∇q¯ and the eddy forciv′˙∇q′ of q¯ are of comparable magnitude and have the tendency to balance one another. It is suggested that transfer by synoptic scale systems acts to maintain the q¯ anomaly against its advection downstream.
Abstract
Using twice daily synoptic charts, objectively analyzed at the National Meteorological Centre, horizontal eddy fluxes of temperature and quasi-geostrophic potential vorticity are computed for the month Of July 1976, when a blocking anticyclone was centered over western Europe. The local time-averaged eddy variance equations are used to provide a dynamical basis for interpreting the spatial pattern of eddy fluxes, and their relation to mean gradients. It is shown that a rotational non-divergent flux can be identified, the cross-gradient component of which balances the mean flow advection of eddy variance. The remaining flux is the dynamically significant one which helps maintain the block and can be understood in terms of a response to sources and sinks of eddy variance.
Abstract
Using twice daily synoptic charts, objectively analyzed at the National Meteorological Centre, horizontal eddy fluxes of temperature and quasi-geostrophic potential vorticity are computed for the month Of July 1976, when a blocking anticyclone was centered over western Europe. The local time-averaged eddy variance equations are used to provide a dynamical basis for interpreting the spatial pattern of eddy fluxes, and their relation to mean gradients. It is shown that a rotational non-divergent flux can be identified, the cross-gradient component of which balances the mean flow advection of eddy variance. The remaining flux is the dynamically significant one which helps maintain the block and can be understood in terms of a response to sources and sinks of eddy variance.
