Water vapour accumulation mechanisms in the Western Mediterranean Basin and the development of European extreme rainfalls

  1. Estíbaliz Saéz de Cámara Oleaga 1
  2. Gotzon Gangoiti Bengoa 1
  3. Lucio Alonso Alonso 1
  4. Marino Navazo Muñoz 1
  5. N. Gómez 1
  6. J. Iza 1
  7. J. A. García 1
  8. Juan Luis Ilardia Garmendia 1
  9. Millán Millán Muñoz 2
  1. 1 Universidad del País Vasco/Euskal Herriko Unibertsitatea

    Universidad del País Vasco/Euskal Herriko Unibertsitatea

    Lejona, España

    ROR https://ror.org/000xsnr85

  2. 2 Fundación Centro de Estudios Ambientales del Mediterráneo
Tethys : revista meteorología y climatología mediterránea

ISSN: 1139-3394

Year of publication: 2011

Issue: 8

Pages: 101-117

Type: Article

DOI: 10.3369/TETHYS.2011.8.10 DIALNET GOOGLE SCHOLAR lock_openOpen access editor

More publications in: Tethys : revista meteorología y climatología mediterránea


This paper examines the role of a recently described warm season circulation at the middletroposphere of northern Africa and that of the recirculation-accumulation mode of the WesternMediterranean Basin (WMB) in the initiation of rainfall episodes in central and eastern Eu-rope. Both of these atmospheric mechanisms can accumulate not only soil dust and pollutantsfor several days but also water vapour by evaporation both over the subtropical Atlantic andthe western and central Mediterranean. Accumulation layers are vented off into the surround-ing area after the irruption of perturbations. In particular, this work explores the exportationof water vapour under perturbed conditions associated with the passage of ‘Vb’ cyclones. Theexceptional rainfall experienced over large areas of central Europe (Elbe/Danube floods) dur-ing August 11-13, 2002 is exposed as a case study. The procedure to simulate the mechanismsinvolves a combination of the Regional Atmospheric Modelling System and HYbrid PArticle Con-centration and Transport modelling systems. MODIS water vapour products, radio-soundings,wind profiler radars and surface-satellite precipitation data are used to verify the simulationoutputs. Our results show that most of the precipitation occurring in the target area during theinitiation and deepening of the episode was very likely originated in an air mass exported fromthe WMB. After our tracking experiment, that air mass, with an initial Atlantic origin, enteredthe WMB and circulated during 4 days (August 6-9) within the marine boundary layer and thecoastal range of mountains of the WMB, accumulating vapour. Then, most of it was transportedon August 10, after the irruption of the ‘Vb’ cyclone Ilse, through the Italian Peninsula and theAdriatic Sea, across the Western Balkans into the target area. The transported vapour togetherwith evaporation en route initiated the rainfall episode.