Contribution of the Southern Annular Mode to Variations in Water Isotopes of Daily Precipitation at Dome Fuji, East Antarctica. Issue 23 (6th December 2021)

• Record Type: Journal Article
• Authors: Kino, Kanon; Okazaki, Atsushi; Cauquoin, Alexandre; Yoshimura, Kei
• Is Part Of: Journal of geophysical research. Volume 126:Issue 23(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-06
• Subjects: stable water isotopes -- Antarctica -- Southern Annular Mode -- GCM -- ice core -- proxy; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2021JD035397
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Water isotopes measured in Antarctic ice cores enable reconstruction at the first order of the past temperature variations. However, the seasonality of the precipitation and episodic events, including synoptic‐scale disturbances, influence the isotopic signals recorded in ice cores. In this study, we adopted an isotope‐enabled atmospheric general circulation model from 1981 to 2010 to investigate variations in climatic factors in δ 18 O of precipitation (δ 18 Op ) at Dome Fuji, East Antarctica. The Southern Annular Mode (SAM), the primary mode of atmospheric circulation in the southern midhigh latitudes, significantly contributes to the isotope signals. Positive δ 18 Op anomalies, especially in the austral winter, are linked to the negative polarity of the SAM, which weakens westerly winds and increases the southward inflow of water vapor flux. Daily variations in temperature and δ 18 Op in Dome Fuji are significantly small in the austral summer, and their contribution to the annual signals is limited. The isotope signals driven by the SAM are a locational feature of Dome Fuji, related to the asymmetric component of the large‐scale atmospheric pattern. Plain Language Summary: In this study, we employed a climate model including water isotopes to investigate how water isotopic components in snowfall precipitation, such as δ 18 Op, are determined in Dome Fuji, East Antarctica. The primary mode of atmospheric circulation in the southern midhigh latitudes (SAM) is significantly associated with daily δ 18 Op signals, particularly in the austral winter. The negative polarity of the SAM weakens westerly winds, increases the inflow from the north to Dome Fuji, and induces large snowfalls that accompany warming. Moreover, the SAM affects the relation between δ 18 Op and the local surface air temperature by shifting the former toward higher values. Thus, it contributes to the warm bias in the accumulated snow due to the lack of cold days. We also demonstrate that this is a locational feature of Dome Fuji. Our results indicate that the δ 18 Op in Antarctica is complexly determined by the global dynamical circulation of the atmosphere and water cycles. Hence, it is crucial to consider the recording processes of isotopic proxies in the interpretation of water isotope records considering past climate variations. Key Points: An isotope‐enabled climate model reproduces the observed daily variations in precipitated stable oxygen isotopes at Dome Fuji Negative polarity of the Southern Annular Mode allows moisture flux with heavy oxygen isotopes to flow from the north around Dome Fuji This polarity contributes to the precipitation of heavy isotopes at Dome Fuji as a locational feature and less contributes at Dome C