Satellite-based climatology of Mediterranean cloud systems and their association with large-scale circulation.

• Published in: Journal of Geophysical Research
• Main Authors: Chaboureau, Jean-Pierre, Claud, C.
• Other Authors: Laboratoire d'aérologie (LAERO), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: North Atlantic Oscillation; satellite observation; Mediterranean cloud system; [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; [SDU]Sciences of the Universe [physics]; Greenland; North Atlantic; North Atlantic oscillation
• Online Access: https://hal.science/hal-00068833; https://hal.science/hal-00068833/document; https://hal.science/hal-00068833/file/2005JD006460.pdf; https://doi.org/10.1029/2005JD006460

The variability of Mediterranean cloud systems is investigated using 8.5 years (from January 1987 to June 1995) of TIROS-N Operational Vertical Sounder (TOVS) observations acquired aboard the National Oceanic and Atmospheric Administration (NOAA) series of operational polar satellites. Cloud systems and troughs are automatically detected with the retrievals of the cloud top pressure (CTP) and the temperature of lower stratosphere (TLS). Observed cloud systems have a typical size of few hundred kilometres with a larger occurrence between March and October. A threefold cloud system typology reveals the presence of an upper-level anomaly for about 30% of the cloud systems in winter, 26% in spring and 7% in autumn (but 23% in October). During summer, in contrast, the forcing is very likely local, and according to the composite analysis, weakly related to upper-level anomaly. During the cold seasons (15 October to 15 April), more cloud systems are found during negative North Atlantic Oscillation (NAO) phase when the north Atlantic storm track takes its southernmost position. Consistently, more systems are observed during the Greenland Anticyclone and the Atlantic Ridge regimes, compared to the Zonal and Blocking regimes. Finally, severe precipitation events over the Alpine region are associated with a warm TLS anomaly upstream the cloud system, showing once more the impact of the upper levels on the weather over this area.