Emergence of representative signals for sudden stratospheric warmings beyond current predictable lead times ...
Major sudden stratospheric warmings (SSWs) are extreme wintertime circulation events of the Arctic stratosphere that are accompanied by a breakdown of the polar vortex and are considered an important source of predictability of tropospheric weather on subseasonal to seasonal timescales over the Nort...
| Main Authors: | , , , , , , |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
ETH Zurich
2021
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.3929/ethz-b-000505291 http://hdl.handle.net/20.500.11850/505291 |
| Summary: | Major sudden stratospheric warmings (SSWs) are extreme wintertime circulation events of the Arctic stratosphere that are accompanied by a breakdown of the polar vortex and are considered an important source of predictability of tropospheric weather on subseasonal to seasonal timescales over the Northern Hemisphere midlatitudes and high latitudes. However, SSWs themselves are difficult to predict, with a predictability limit of around 1 to 2 weeks. The predictability limit for determining the type of event, i.e., wave-1 or wave-2 events, is even shorter. Here we analyze the dynamics of the vortex breakdown and look for early signs of the vortex deceleration process at lead times beyond the current predictability limit of SSWs. To this end, we employ a mode decomposition analysis to study the potential vorticity (PV) equation on the 850 K isentropic surface by decomposing each term in the PV equation using the empirical orthogonal functions of the PV. The first principal component (PC) is an indicator of the ... : Weather and Climate Dynamics, 2 (3) ... |
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