New insights into the climatic signal from firn cores at the northern
Francisco Fernandoy1, Dieter Tetzner2, Hanno Meyer3, Guisella Gacitúa4, Kirstin Hoffmann3, and Ulrike Falk51Facultad de Ingenieria, Universidad Andres Bello, Viña del Mar, 2531015, Chile 2Center for Climate and Resilience Research, University of Chile, Santiago, 8370361, Chile 3Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Research Unit Potsdam, Telegrafenberg A43, 14473 Potsdam, Germany 4Programa GAIA-Antártica, Universidad de Magallanes, Punta Arenas, 6210427, Chile 5Climate Lab, Geography Depart., University Bremen, 28334 Bremen, Germany
Received: 30 Dec 2016 – Accepted for review: 16 Jan 2017 – Discussion started: 24 Jan 2017
Abstract. The Antarctic Peninsula is one of the most challenging regions of Antarctica from a climatological perspective, owing to the recent atmospheric and oceanic warming. The steep topography and a lack of long–term and in situ meteorological observations complicate extrapolation of existing climate models to the sub-regional scale. Here, we present new evidence from the northern Antarctic Peninsula to demonstrate how stable water isotopes of firn cores and recent precipitation samples can reveal climatic processes related to nearby oceanic and atmospheric conditions. A noticeable effect of the sea ice cover on local temperatures and atmospheric modes, in particular the Southern Annular Mode (SAM), is demonstrated. In years with large sea ice extension in winter (negative SAM anomaly), an inversion layer in the lower troposphere develops at the coastal zone. Therefore, an isotope–temperature relationship valid for all seasons cannot be concluded. The δ–T relationship rather depends on seasonal variability of oceanic conditions. Transitional seasons (autumn and spring) are both stable seasons with an isotope–temperature gradient of +0.69 ‰ °C−1. The firn stable isotope composition reveals that the near–surface temperature at the Antarctic Peninsula shows a decreasing trend (−0.33 °C y−1) between 2008 and 2014. Moreover, the deuterium excess (dexcess) has been demonstrated to be a reliable indicator of seasonal oceanic conditions, and therefore suitable to improve a firn age model based on seasonal dexcess variability. The annual accumulation rate in this region is highly variable, ranging between 1060 kg m−2 y−1 and 2470 kg m−2 y−1 from 2008 to 2014. The combination of isotopic and meteorological data is key for reconstructing recent climatic conditions with a high temporal resolution in polar regions where no direct observation exists
Fernandoy, F., Tetzner, D., Meyer, H., Gacitúa, G., Hoffmann, K., and Falk, U.: New insights into the climatic signal from firn cores at the northern
Antarctic Peninsula, The Cryosphere Discuss., doi:10.5194/tc-2016-298, in review, 2017.
Francisco Fernandoy et al.
Francisco Fernandoy et al.
High resolution stable water isotope composition (d18O and dD) of two firn cores at the northern Antarctic Peninsula
F. Fernandoy, D. Tetzner, H. Meyer, G. Gacitúa, K. Hoffmann, and U. Falk