Article

Meteorology and Atmospheric Physics

, Volume 90, Issue 3, pp 225-243

First online:

The 2001 Mesoscale Convective Systems over Iberia and the Balearic Islands

  • R. García-HerreraAffiliated withDepartamento de Física de la Tierra II, Fac. De C.C Físicas, Universidad Complutense de Madrid
  • , D. BarriopedroAffiliated withDepartamento de Física de la Tierra II, Fac. De C.C Físicas, Universidad Complutense de Madrid
  • , E. HernándezAffiliated withDepartamento de Física de la Tierra II, Fac. De C.C Físicas, Universidad Complutense de Madrid
  • , D. ParedesAffiliated withDepartamento de Física de la Tierra II, Fac. De C.C Físicas, Universidad Complutense de Madrid
  • , J. F. CorreosoAffiliated withDepartamento de Física de la Tierra II, Fac. De C.C Físicas, Universidad Complutense de Madrid
  • , L. PrietoAffiliated withDepartamento de Física de la Tierra II, Fac. De C.C Físicas, Universidad Complutense de Madrid

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Summary

This paper characterizes Mesoscale Convective Systems (MCSs) during 2001 over Iberia and the Balearic Islands and their meteorological settings. Enhanced infrared Meteosat imagery has been used to detect their occurrence over the Western Mediterranean region between June and December 2001 according to satellite-defined criteria based on the MCS physical characteristics.

Twelve MCSs have been identified. The results show that the occurrence of 2001 MCSs is limited to the August–October period, with September being the most active period. They tend to develop during the late afternoon or early night, with preferred eastern Iberian coast locations and eastward migrations. A cloud shield area of 50.000 km2 is rarely exceeded. When our results are compared with previous studies, it is possible to assert that though 2001 MCS activity was moderate, the convective season was substantially less prolonged than usual, with shorter MCS life cycles and higher average speeds. The average MCS precipitation rate was 3.3 mm·h−1 but a wide range of values varying from scarce precipitation to intense events of 130 mm·24 h−1 (6 September) were collected. The results suggest that, during 2001, MCS rainfall was the principal source of precipitation in the Mediterranean region during the convective season, but its impact varied according to the location.

Synoptic analysis based on NCEP/NCAR reanalysis show that several common precursors could be identified over the Western Mediterranean Sea when the 2001 MCSs occurred: a low-level tongue of moist air and precipitable water (PW) exceeding 25 mm through the southern portion of the Western Mediterranean area, low-level zonal warm advection over 2 °C·24 h−1 towards eastern Iberia, a modest 1000–850 hPa equivalent potential temperature (θe) difference over 20 °C located close to the eastern Iberian coast, a mid level trough (sometimes a cut-off low) over Northern Africa or Southern Spain and high levels geostrophic vorticity advection exceeding 12·10−10 s−2 over eastern Iberia and Northern Africa. Finally, the results suggest that synoptic, orographic and a warm-air advection were the most relevant forcing mechanisms during 2001.