A reconstruction of the ice thickness of the Antarctic Peninsula Ice Sheet north of 70° S

Abstract. Accurate knowledge of the ice thickness distribution on the Antarctic Peninsula Ice Sheet (APIS) is important to assess both its present and its future responses to climate change. The aim of the present work is to improve the ice thickness distribution map of the APIS using a two-step approach. Its first step, which readily assimilates ice thickness observations, considers two different rheological assumptions and then applies a further mass conservation step in fast-flowing areas, where it also assimilates ice velocity observations. Using this method, we calculated a total volume of 27.7±13.9×103 km3 for the APIS north of 70° S. Using our ice thickness map and the flux gate method, we estimated a total ice discharge of 97.7±16.9 km3 a−1 over the period of 2015–2017, which is an intermediate value within the range of estimates made by other authors. Our thickness results show relatively low deviations from other reconstructions on the glaciers used for validation. Qualitative analysis further reveals that our method properly reproduces the observed morphology of regional features, such as plateau areas, ice falls, and valley glaciers, although there are large errors when compared to independent validation data. Despite the advances made in data assimilation and inversion modeling, further refinement of input data, particularly ice thickness measurements, remains crucial to improve the accuracy of the APIS ice thickness mapping efforts.