Multivariable cyclone analysis in the Mediterranean region

Fanni Dóra Kelemen, Judit Bartholy, Rita Pongrácz

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

This paper analyzes midlatitude cyclones identified and tracked in the Mediterranean region for the recent past, between 1981 and2010. The Mediterranean region is especially interesting since the complex land orography favors lee cyclogenesis, and the warm sea area provides latent heat for the developing cyclones. These cyclones may result in heavy precipitation, even flood events affecting southern and central Europe, including Hungary. Cyclones are identified using two different reanalyses, the ERA Interim reanalysis from ECMWF at 0.75° horizontal resolution and the NCEP-DOE R2 reanalysis at 2.5° horizontal resolution. For the identification, a multivariable approach is used to eliminate and assess the uncertainties rising from the choice of a specific variable, which is particularly important in the Mediterranean, where the systems are tend to be weak and shallow. Mean sea level pressure (MSLP), geopotential heights of the 1000 hPa, and the 850 hPa isobaric levels are used as main variables, and relative vorticity at 850 hPa isobaric level serves, an additional variable. The applied algorithm has uni-and bivariate modes. In the bivariate mode, relative vorticity at 850 hPa is added to the main variable. The results suggest that time series of annual number of cyclones using the two reanalyses correlate significantly, however, using the higher resolution dataset, more cyclones can be identified. The largest and the smallest frequency of cyclones over the entire domain occur in spring and summer, respectively. The largest spread of the multi-variable ensemble is in summer, probably caused by non-frontal thermal lows. Furthermore, summer is mostly dominated by short-lived cyclones. The main cyclogenesis regions are the Gulf of Genoa and the Cyprus region, with some minor centers at the Adriatic Sea, the northern part of the Black Sea, and the Iberian Peninsula. The cyclone frequency trend is slightly increasing in most parts of the region, especially over the Adriatic Sea and near Cyprus. Hungary is affected annually by approximately 30 cyclones from the Mediterranean area, most frequently in spring.

Original languageEnglish
Pages (from-to)159-184
Number of pages26
JournalIdojaras
Volume119
Issue number2
Publication statusPublished - Apr 1 2015

Keywords

  • Cyclone climatology
  • Cyclone identification
  • Cyclone tracking
  • Geopotential height
  • MSLP
  • Mediterranean region
  • Reanalysis
  • Relative vorticity

ASJC Scopus subject areas

  • Atmospheric Science

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