ISSN:
1436-5065
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geography
,
Physics
Notes:
Summary Mechanisms associated with Alpine lee cyclogenesis during the early phase of their generation are investigated using a variational quasigeostrophic filter technique. It was possible to extract the quasigeostrophic signal from the available analyzed real data set. The results presented here are for the 11–12 March 1982, an example of so-called “orographically induced” lee cyclogenesis. Non-quasigeostrophic fields, calculated as a difference between observations and the quasigeostrophic fields, show significant magnitudes indicating the possible importance of non-quasigeostrophic processes. A “dipole” structure in the residual geopotential field was observed, similar to the results of numerical model experiments. Also, a strong upper-level non-quasigeostrophic divergence was found in the Alpine region 24 hours prior to lee cyclogenesis, lasting for 6–12 hours. On the other hand, quasigeostrophic results indicate only a local effect of mountain slopes, suggesting possibly a dominant role of the low-level blocking. A hypothetical “scenario” of Alpine lee cyclogenesis is proposed, based on results obtained here.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01025610
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