A GCM‐based analysis of circulation controls on δ18O in the southwest Yukon, Canada: Implications for climate reconstructions in the region

[1] To improve our understanding of paleoclimatic records in the southwest Yukon, we examined controls on precipitation δ18O using an isotopically-equipped atmospheric general circulation model (GCM). Our results show that, particularly during the cool-season, elevated δ18O is associated with a deeper Aleutian Low and stronger southerly moisture flow, while lower δ18O is associated with the opposite meteorological conditions. These results suggest that the large mid-19th century shift towards lower δ18O values seen in paleoclimate records from the region was associated with a shift towards a weaker Aleutian Low. While in disagreement with a previous interpretation of this shift, it is consistent with records of glacial advance and tree-ring growth during the same period, and observational studies of Aleutian Low controls on temperature and precipitation in the region.