A 400-year reconstruction of July relative air humidity for the Vienna region (eastern Austria) based on carbon and oxygen stable isotope ratios in tree-ring latewood cellulose of oaks (Quercus petraea Matt. Liebl.)

Abstract

Stable isotope chronologies of carbon and oxygen for the period from 1600 to 2003 and of non-exchangeable hydrogen for the last century were constructed base upon tree-ring latewood cellulose from oaks (Quercus petraea Matt. Liebl.) grown in the Vienna region (Austria). The stable isotope ratios reflect highly significantly the summer climate conditions. For the reconstruction of temperature and relative air humidity, verifiable bivariate linear regression models were calculated. Hydrogen isotope values clearly enhanced the model verification. The reconstruction of July relative air humidity in the region Vienna (Austria) for the last 400 years was carried out with carbon and oxygen stable isotope ratios. During this period the humidity oscillated around a mean of 74.7 ± 4.4% with wet and dry periods in a cycle of approximately 130 years. Predominant wet conditions were reconstructed for the periods 1690–1710, 1765–1820 and 1900–1960, predominant dry periods for 1715 to 1730, 1830 to 1870 and from approximately 1960 to present. Extreme wet months of July were identified in the years 1663, 1795, 1816, 1906, 1915 and 1926, exceptionally dry were inferred for 1616, 1636, 1637, 1751, 1822, 1857, 1863, 1990, 1992 and 2001.