An investigation of the controls on Irish precipitation δO values on monthly and event timescales.

This two-year study investigates the relative influence of meteorological variables (precipitation amount and temperature), atmospheric circulation, air mass history, and moisture source region on Irish precipitation oxygen isotopes (δO) on event and monthly timescales. Single predictor correlations reveal that on the event scale, 20% of δO variability is attributable to the amount effect and 7% to the temperature effect while on the monthly timescale the North Atlantic Oscillation accounts for up to 20% of δO variability and the amount and temperature effects are not significant. In comparison, multivariate linear regression reveals that the interaction of temperature and precipitation amount explains up to 40% of δO variance at event and monthly timescales. Five-day kinematic back trajectories suggest that the amount-weighted mean δO value of southerly- and northerly-derived events are lower by 2‰ relative to events derived from the west. Because air mass history and atmospheric circulation appear to influence δO in Ireland, Irish paleo-δO proxy records are best interpreted as reflecting a combination of parameters, not just paleotemperature or paleorainfall. [ABSTRACT FROM AUTHOR]