A climatology of cut-off lows at 200 hPa in the Northern Hemisphere, 1990–1994
✍ Scribed by Kentarchos, A. S.; Davies, T. D.
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 363 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0899-8418
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✦ Synopsis
A statistical study of the size, temporal and spatial distribution of cut-off low (COL) systems on the 200 hPa pressure surface has been conducted for the Northern Hemisphere. The 200 hPa surface is of relevance for stratosphere -troposphere exchange processes. The study covered a 5-year period and recorded information (duration, size, position, movement) for all COLs that lasted for 2 days or more. Cut-off lows form more often in summer than winter and in preferred geographical regions. The majority of COLs lasted 2 -3 days and very few lasted more than 10 days. Cut-off lows were found over a wide range of sizes, but the majority were between 200 and 1200 km (max diameter in latitude). Approximately 50% of the COLs that lasted more than 3 days moved considerable ( \ 600 km) distances. Although their motion was, as a rule, rather irregular, it was seen that COL systems would characteristically move northwards, or eastwards-northwards as they began to decay. Finally, there was some degree of interannual variability in COL distribution.