Re-evaluation of the effects of precipitation amount and temperature on precipitation δ18O at the monthly and interannual timescales

Abstract

Proxy records of the oxygen isotope ratio of 18O/16O of past precipitation (δ18Op) have played an important role in revealing past hydroclimatic changes, on the basis of global observed relationships between monthly precipitation δ18Op and both precipitation amount and temperature only of a few years as reported by Dansgaard in 1964. It is therefore crucial to systematically re-evaluate the relationships using modern instrumental data. We analysed monthly and annual mean correlations from 108 global stations over the past about 60 years. Consistent with previously reported results, monthly δ18Op values in the high latitudes (≥60°) show a significant positive correlation with temperature (referred to as ‘temperature effect’) and a negative trend with precipitation amount in the low latitudes (≤20°) (‘amount effect’). However, these correlations do not hold true for yearly mean data for more than three-quarters of the stations evaluated. This indicates that the relationships between the different temporal resolutions could be more complicated than previously thought. For the related natural archives, such as ice cores, sediments, and carbonates, further careful evaluation is required to establish the robustness of their paleoclimatic implications. HIGHLIGHTS 108 GNIP stations were collected to re-analyse the relationships between δ18Op and climate variables on monthly and interannual timescales.; The relationships between δ18Op and climate variables varied on monthly and interannual timescales.; The results implied that the change of precipitation isotopic values may not be dominated by local climate change, but more likely a response to global atmospheric circulation.;

Keywords

• gnip stations
• paleo-δ18op records
• precipitation amount effect
• precipitation δ18o
• temperature effect