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Climatological features of cutoff low systems in the Northern Hemisphere

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Nieto, Raquel and Gimeno, Luis and Torre, Laura de la and Ribera, Pedro and Gallego, David and García Herrera, Ricardo and García, José Agustín and Nuñez, Marcelino and Redaño, Ángel and Lorente, Jerónimo (2005) Climatological features of cutoff low systems in the Northern Hemisphere. Journal of climate, 18 (16). pp. 3085-3103. ISSN 0894-8755

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Official URL: http://dx.doi.org/10.1175/JCLI3386.1


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Abstract

This study presents the first multidecadal climatology of cutoff low systems in the Northern Hemisphere. The climatology was constructed by using 41 yr (1958-98) of NCEP-NCAR reanalysis data and identifying cutoff lows by means of an objective method based on imposing the three main physical characteristics of the conceptual model of cutoff low (the 200-hPa geopotential minimum, cutoff circulation, and the specific structure of both equivalent thickness and thermal front parameter fields). Several results were confirmed and climatologically validated: 1) the existence of three preferred areas of cutoff low occurrence (the first one extends through southern Europe and the eastern Atlantic coast, the second one is the eastern North Pacific, and the third one is the northern China-Siberian region extending to the northwestern Pacific coast; the European area is the most favored region); 2) the known seasonal cycle, with cutoff lows forming much more frequently in summer than in winter; 3) the short lifetime of cutoff lows, most cutoff lows lasted 2-3 days and very few lasted more than 5 days; and 4) the mobility of the system, with few cutoff lows being stationary. Furthermore, the long study period has made it possible (i) to find a bimodal distribution in the geographical density of cutoff lows for the European sector in all the seasons (with the exception of winter), a summer displacement to the ocean in the American region, and a summer extension to the continent in the Asian region, and (ii) to detect northward and westward motion especially in the transitions from the second to third day of occurrence and from the third to fourth day of occurrence. The long-term cutoff low database built in this study is appropriate to study the interannual variability of cutoff low occurrence and the links between cutoff lows and jet stream systems, blocking, or major modes of climate variability as well as the global importance of cutoff low in the stratosphere-troposphere exchange mechanism, which will be the focus of a subsequent paper.


Item Type:Article
Additional Information:

© 2005 American Meteorological Society. This work was supported by the Spanish Ministry and Science and Technology (MCYT) under Grant REN2002-04558-C04-02 and by the Galician
Programme of Research and Development under Grant PGIDIT03PXIC38301PN. The authors thank three anonymous reviewers for their helpful comments and suggestions.

Uncontrolled Keywords:Stratosphere-troposphere exchange; Off-low systems; Precipitation; Profiles; Atlantic; Cyclone
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:34776
Deposited On:13 Jan 2016 16:32
Last Modified:10 Dec 2018 15:05

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