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Mid-latitude weather, waves and vortices:
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| Climate variability and extreme events in mid-latitudes are connected to complex dynamical structures propagating around the whole globe.These structures build bridges in time and space connecting weather and climate and large distances as, for example, wet and dry periods in Europe and Central Asia. The potential vorticity (PV) is a combination of rotation and stratification, and allows to visualize these structures and their dynamics. |
| A simulation of an idealized Earth-type atmosphere is produced with PUMA (Portable University Model of the Atmosphere) at a horizontal resolution of T170 with 20 equidistant vertical layers. For demonstration, the absolute value of the potential vorticity (Units: PVU, i.e. Potential Vorticity Units) on the 315 K isentrope is shown in the movie. |
| The transition between tropospheric and stratospheric air in mid-latitudes is organized in a sharp PV front with wave- and vortex-like behaviour. The disturbances (green-yellow PV areas) formed during wave-breaking events can move rapidly along the front and trigger new breaking events downstream. The dynamical behaviour of the PV front in the upper troposphere and lower stratosphere has a direct influence on the weather at the surface. Traveling instabilities can explain the correlation of weather events often thousands of kilometers apart. The statistics of wave breaking and vortex formation yields a measure for the climate variability including extreme events. |
