Challenges associated with the climatic interpretation of water stable isotope records from a highly resolved firn core from Adélie Land, coastal Antarctica
oleh: S. Goursaud, S. Goursaud, V. Masson-Delmotte, V. Favier, S. Preunkert, M. Legrand, B. Minster, M. Werner
| Format: | Article |
|---|---|
| Diterbitkan: | Copernicus Publications 2019-04-01 |
Deskripsi
<p>A new 21.3 m firn core was drilled in 2015 at a coastal Antarctic high-accumulation site in Adélie Land (66.78<span class="inline-formula"><sup>∘</sup></span> S; 139.56<span class="inline-formula"><sup>∘</sup></span> E, 602 m a.s.l.), named Terre Adélie 192A (TA192A).</p> <p>The mean isotopic values (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">19.3</mn><mspace width="0.125em" linebreak="nobreak"/><mi mathvariant="normal">‰</mi><mo>±</mo><mn mathvariant="normal">3.1</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="70pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="8c7cb92ef210551f462adaf6959f644a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-13-1297-2019-ie00001.svg" width="70pt" height="10pt" src="tc-13-1297-2019-ie00001.png"/></svg:svg></span></span> ‰ for <span class="inline-formula"><i>δ</i><sup>18</sup>O</span> and <span class="inline-formula">5.4 ‰±2.2</span> ‰ for deuterium excess) are consistent with other coastal Antarctic values. No significant isotope–temperature relationship can be evidenced at any timescale. This rules out a simple interpretation in terms of local temperature. An observed asymmetry in the <span class="inline-formula"><i>δ</i><sup>18</sup>O</span> seasonal cycle may be explained by the precipitation of air masses coming from the eastern and western sectors in autumn and winter, recorded in the <span class="inline-formula"><i>d</i></span>-excess signal showing outstanding values in austral spring versus autumn. Significant positive trends are observed in the annual <span class="inline-formula"><i>d</i></span>-excess record and local sea ice extent (135–145<span class="inline-formula"><sup>∘</sup></span> E) over the period 1998–2014.</p> <p>However, process studies focusing on resulting isotopic compositions and particularly the deuterium excess–<span class="inline-formula"><i>δ</i><sup>18</sup>O</span> relationship, evidenced as a potential fingerprint of moisture origins, as well as the collection of more isotopic measurements in Adélie Land are needed for an accurate interpretation of our signals.</p>