The Berlin troposphere‐stratosphere‐mesosphere GCM: Climatology and forcing mechanisms
Abstract The climatological structure of the Berlin troposphere‐stratosphere‐mesosphere general circulation model is presented and compared with observations. the zonal‐mean zonal wind and temperature display some successes for the simulation in that all of the climatological features are captured,...
| Published in: | Quarterly Journal of the Royal Meteorological Society |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
1997
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1002/qj.49712354014 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.49712354014 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.49712354014 |
| Summary: | Abstract The climatological structure of the Berlin troposphere‐stratosphere‐mesosphere general circulation model is presented and compared with observations. the zonal‐mean zonal wind and temperature display some successes for the simulation in that all of the climatological features are captured, but there are some systematic errors regarding their location and strength. In particular, the location and structure of the polar‐night jet in the northern winter is incorrect: it is located too far polewards at high levels and is too weak in the middle and lower stratosphere. On the positive side, there is a separation between the polar‐night jet and the subtropical jet. the temperature in the winter polar upper troposphere and lower stratosphere is too high, presumably arising from the treatment of radiative processes. Consistent with hydrostatic balance, the 30 hPa (and other) isobaric surface lies too high. the polar vortex is both too asymmetric and too weak. This leads to an underestimate of the modelled zonal velocity, which is consistent with the poleward (rather than equatorward) propagation of the stationary planetary waves, in the lower and middle stratosphere. In the upper stratosphere the poleward heat and momentum fluxes due to these waves are too strong. Despite these systematic errors, the seasonal evolution of both hemispheres is quite well simulated: the large variability and the strong, episodic forcing of the northern winter contrasts well with the relatively stable southern winter and the breakdown of the southern polar vortex in springtime. the magnitude of the variability in the northern hemisphere is too small in the model and it is proportionally too large in the early winter. |
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