Imprint of atmospheric rivers on stable-oxygen isotopes ratio in Greenland ice cores: an assessment

The stable oxygen isotope ratio (δ¹⁸O) measured in ice cores is widely used to reconstruct past climate variability on short and long timescales. Among synoptic processes, atmospheric rivers (ARs) play a key role in the poleward transport of moisture. ARs are long, narrow corridors of intense horizontal water vapour transport, typically associated with extratropical cyclones. They convey large amounts of moisture from distant, often low-latitude source regions together with warm air advection, thereby introducing a distinct isotopic signature into precipitation. Through snowfall, the isotopic composition of atmospheric water vapour is recorded in snow and ultimately preserved in ice cores. 

While several studies have examined the influence of ARs on δ¹⁸O variability in Antarctic ice cores, a comparable assessment for Greenland remains more limited until now.

Here, we investigate the imprint of ARs on δ¹⁸O variability in Greenland ice cores using virtual firn cores (VFCs) derived from a new high-resolution (0.5°) simulation performed with the isotope-enabled atmospheric general circulation model ECHAM6-wiso nudged to ERA5 reanalyses. VFCs are generated for the Renland Ice Cap (RECAP) and Southeastern Dome (SED) sites and evaluated against their corresponding very high-resolution measured δ¹⁸O records.

Our results show that ARs do not fundamentally change the δ¹⁸O variability. However, they exert a pronounced influence on seasonal and subseasonal δ¹⁸O variations during periods when AR-related snowfall contributes a substantial fraction of total precipitation. On the subseasonal timescale, individual AR events are found to increase δ¹⁸O values by approximately 3‰ on average, with extreme cases reaching up to 5‰.