How does sea ice influence <i>δ</i><sup>18</sup>O of Arctic precipitation?

Abstract

Abstract. This study investigates how variations in Arctic sea ice and sea surface conditions influence δ 18 O of presentday Arctic precipitation. This is done using the model iso-CAM3, an isotope-equipped version of the National Center for Atmospheric Research Community Atmosphere Model version 3. Four sensitivity experiments and one control simulation are performed with prescribed sea surface temperature (SST) and sea ice. Each of the four experiments simulates the atmospheric and isotopic response to Arctic oceanic conditions for selected years after the beginning of the satellite era in 1979.Changes in sea ice extent and SSTs have different impacts in Greenland and the rest of the Arctic. The simulated changes in central Arctic sea ice do not influence δ 18 O of Greenland precipitation, only anomalies of Baffin Bay sea ice. However, this does not exclude the fact that simulations based on other sea ice and sea surface temperature distributions might yield changes in the δ 18 O of precipitation in Greenland. For the Arctic, δ 18 O of precipitation and water vapour is sensitive to local changes in sea ice and sea surface temperature and the changes in water vapour are surface based. Reduced sea ice extent yields more enriched isotope values, whereas increased sea ice extent yields more depleted isotope values. The distribution of the sea ice and sea surface conditions is found to be essential for the spatial distribution of the simulated changes in δ 18 O.

Varying regional <i>δ</i><sup>18</sup>O–temperature relationship in high-resolution stable water isotopes from east Greenland

“…6.2, which showed that the winter-averaged δ 18 O signal correlated with temperatures all over Greenland, resembling the anticorrelations between NEEM δ 18 O and Baffin Bay SIC that have previously been found (Steen-Larsen et al, 2011;Zheng et al, 2018). Moreover, the results are consistent with Faber et al (2017), who found that changes in the Baffin Bay sea ice coverage can impact the δ 18 O precipitation over Greenland (by using an atmospheric general circulation model coupled with water isotopologue tracing (isoCAM3)). Furthermore, the analysis shows only a small patch of correlation between the δ 18 O series and the SIC south of Fram Strait.…”

“…In order to evaluate this hypothesis, more studies using isotope-enabled modeling are needed. The impact of changes in sea ice on the Arctic δ 18 O precipitation has previously been investigated by Faber et al (2017), who found that the δ 18 O precipitation on Greenland only responded to perturbations of the Baffin Bay sea ice coverage. However, they used a horizontal resolution of ∼ 1.4 • × 1.4 • which barely resolved the Renland Ice Cap of ∼ 1200 km 2 .…”

“…Nonetheless, all the presented ice cores correlated significantly during the 1801-1987 period. The δ 18 O variability can be further analyzed by examining the mean single series SNR which provides an insight into the amount of signal and noise in the δ 18 O series (Fisher et al, 1985). Noise can originate from depositional effects such as wind shuffling of snow and melt layers and from dating uncertainties (±1 year) in between the three cores.…”

A major increase in winter snowfall during the middle Holocene on western Greenland caused by reduced sea ice in Baffin Bay and the Labrador Sea

“…Distillation and temperature are negatively correlated, and as a result, the modern temperature-δ 2 H precip relationship increases northward along western Greenland, from À0.1‰°C À1 at Kangilinnguit to 3.4‰°C À1 at Thule [IAEA/WMO, 2011] ( Figure S3 in the supporting information). Temperature-δ 2 H precip relationships likely changed through time, as an increase in sea ice cover would increase transport distance and cause more distillation during transport [Jouzel et al, 1997;Faber et al, 2015]. Thus, even if temperature is the main mechanism influencing past δ 2 H precip , records of precipitation isotopes in this region should be used to infer only qualitative changes in temperature, unless independent constraints can be placed on the temperature-δ 2 H precip paleorelationship.…”

Resolving the controls of water vapour isotopes in the Atlantic sector

“…In polar regions, variations in sea ice extent are supposed to affect regional precipitation amounts 20 and to be reflected in the water isotopic composition 21–23 . Current understanding of the impact of sea ice on the vapour isotopic composition is, however, still limited by the number of observations available in sea ice covered areas 24,25 .…”