60-year trends of δ~(18)O in global precipitation reveal large scale hydroclimatic variations

摘要

Sixty years of monthly data series of delta O-18 in precipitation revealed distinctive decadal long-term patterns and break points for the isotope composition of global precipitation. Our results showed that at the multi-decadal scale, delta O-18 in precipitation displayed changes due to large-scale hydroclimate processes, and particularly, from atmospheric oscillations. Break point and segmented regression trend analyses for delta O-18 and air temperature revealed influences of the North Atlantic Oscillation (NAO) on the long-term isotope variability for most continental stations in Northern Hemisphere. Long-term trends of 318O and precipitation amount for Southern Hemisphere stations were mostly indicative of changes in regional hydroclimate processes driven by the larger scale Atlantic and Pacific atmospheric oscillations. For oceanic island stations, the delta O-18 variations could be described by sinusoidal trends with a 20-40 years-time cycle and delta O-18 amplitude of-1-2 parts per thousand, suggesting these stations have a higher sensitivity to multi-decadal atmospheric circulation. Our findings reveal that coordinated long-term monitoring of stable isotopes in precipitation, coupled with basic meteorological parameters such as air temperature and precipitation amount, are essential to better understand the impact of larger scale hydroclimate variation on regional and local climate variability, and to help interpret long-term hydroclimatic changes of the past, present and future.