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  • Publication
    Métadonnées seulement
    Heat and drought 2003 in Europe: a climate synthesis
    (2006) ;
    Mayer, Helmut
    ;
    Dupont, Olivier
    ;
    Schindler, Dirk
    ;
    Gartner, Karl
    ;
    Kropp, JĂĽrgen
    ;
    Menzel, Anette
    Heat and drought were extreme in summer 2003 in Europe. Climatic data show that most extreme were maximum air temperatures in June and August; maps of these two months show a striking similarity in geographical range. Over wide regions, monthly mean temperatures were more than 4 degrees C above the long term mean values. The heat lasted from May to September in large parts of western and central Europe. The lack of precipitation was most severe in summer 2003 but precipitation was generally below normal from February 2003 until June 2004 ( with the exception of two months). Sunshine duration was above normal, particularly in regions which usually have rainy and cloudy episodes in summer, and relative air humidity was below normal during the whole year of 2003. The drought experienced by the vegetation in summer 2003 was exacerbated by the length of the period with scarce precipitation and humidity, by the heat during the summer and by long sunshine duration.
  • Publication
    Métadonnées seulement
    To what extent can oxygen isotopes in tree rings and precipitation be used to reconstruct past atmospheric temperature? A case study
    (2003) ;
    Saurer, Matthias
    ;
    Cherubini, Paolo
    We analyzed the relationship between air temperature and oxygen isotopes measured in tree rings of silver fir (Abies alba Mill.) from a long-term forest ecosystem research plot in the Swiss Jura mountains (LWF project). The oxygen isotope data were compared with a century-long meteorological series of air temperature data. Measurements of oxygen isotope ratios in precipitation were also used for comparison. Results show that the late-wood tree-ring series is significantly correlated with May to August temperatures. Correlations were higher for maximum (daytime) air temperature and even better for air temperature measured on rainy days only. We stress that trends in maximum temperature series for this time of the year, like trends in oxygen isotope ratios series from tree rings, are completely different from trends in yearly mean temperature. Indeed, maximum temperature trends during the vegetation period slightly decreased during the 20th century, whereas yearly means increased strongly.