Reconstruction of annual accumulation rate on firn, synchronising H₂O₂ concentration data with an estimated temperature record

• Main Authors: J. M. Travassos, S. S. Martins, M. Potocki, J. C. Simões
• Format: Article
• Language: English
• Published: Copernicus Publications 2021-07-01
• Series: The Cryosphere
• Online Access: https://tc.copernicus.org/articles/15/3495/2021/tc-15-3495-2021.pdf

<p>This work deals with reconstructing firn layer thicknesses at the deposition time from the firn's observed thickness in ice cores, thus reconstructing the annual accumulation, yielding a timescale and an ice-core chronology. We employed a dynamic time warping algorithm to find an optimal, non-linear alignment between an H<span class="inline-formula">₂</span>O<span class="inline-formula">₂</span> concentration data series from 98 m worth of ice cores of a borehole on the central ice divide of the Detroit Plateau, the Antarctic Peninsula, and an estimated local temperature time series. The viability and the physical reliability of the procedure are rooted in the robustness of the seasonal marker H<span class="inline-formula">₂</span>O<span class="inline-formula">₂</span> in a high-accumulation context, which brought the entire borehole to within the operational life span of four Antarctic stations around the Antarctic Peninsula. The process was heavily based on numerical optimisation, producing a mathematically sound match between the two series to estimate the annual layering efficiently on the entire data section at once, being disposition-free. The results herein confirm a high annual accumulation rate of <span class="inline-formula"><i>a</i>_<i>N</i>=2.8</span> m w.e./yr, which is of the same order of magnitude as and highly correlated with that of the Bruce Plateau and twice as large as that of the Gomez Plateau, <span class="inline-formula">300</span> and <span class="inline-formula">1200</span> <span class="inline-formula">km</span> further south, respectively.</p>