The Dominant Role of Brewer‐Dobson Circulation on ¹⁷O‐Excess Variations in Snow Pits at Dome A, Antarctica

Abstract

Recent studies have suggested that water isotopologues in snow pits from remote East Antarctica can be influenced by the input of stratospheric water, which has anomalously high 17O‐excess values. However, it remains unclear whether the 17O‐excess records preserved in snow and ice from this region can be used to reconstruct stratosphere‐troposphere exchange (STE). In this study, we present high‐resolution 17O‐excess records from two snow pits at Dome A, the highest point of the Antarctic ice sheet. The 17O‐excess records show a significant positive correlation with the strength of the Brewer‐Dobson circulation (BDC), the hemispheric‐scale troposphere‐stratosphere overturn circulation. Stronger BDC leads to more stratospheric water input over Antarctica and higher 17O‐excess, and vice versa. In addition, the 17O‐excess records also have a significant positive correlation with the Southern Annular Mode (SAM) index, because SAM modulates Antarctic precipitation, which has a dilution effect on the stratospheric water input. The 17O‐excess records do not show significant correlations with local temperature and relative humidity in the moisture source region. These results suggest the dominant effect of BDC on 17O‐excess and indicate the potential for using 17O‐excess records in ice cores from remote sites in East Antarctica for reconstructing long‐term variations of STE, and understanding their mechanisms and climate effects.

Extraterrestrial dust flux monitoring at Antarctic Vostok station: New collection of extraterrestrial spherules fallen from May to September 2017

“…The observation of a “cutoff of the spectrum” in the region of 3 μm for the size distribution plot (Figure 5a) can serve as a confirmation of such a scenario. The reliability of this scenario is also confirmed by the recent observations of admixture of stratospheric water in the precipitations over Antarctica (Pang et al., 2022).…”

Ice Core 17O Reveals Past Changes in Surface Air Temperatures and Stratosphere to Troposphere Mass Exchange

“…It is also possible that all sources and processes affecting natural water 17 O levels are not included in the presently accepted MDF coefficient of 0.528. As noted above, this coefficient was estimated from a dataset that included samples of Antarctic ice [18,19,30], which has been shown to contain a stratospheric input [26,27]. Similarly, upper tropospheric moisture contributing to extratropical precipitation may also include a MIF component because of the stratosphere to troposphere transport that occurs mostly at high latitudes [42].…”

“…A stratospheric input is known to influence the 17 O contents of tropospheric gases (ozone, molecular oxygen and carbon dioxide) or nitrate and sulfate aerosols [25]. Stratospheric 17 O influence has also been shown for Antarctic [26,27] and Arctic [28] snow, but it is not considered to be a ubiquitous source contributing normally to global precipitation [17][18][19][20][21][22]24].…”