Frontal ablation is a major component of ice loss in Patagonia but remains uncertain outside the Patagonian icefields.We present a multiple fluxgate method to quantify frontal ablation near the calving front, capturing spatial heterogeneity and complex tongue geometries.We apply the method to Manso Glacier (Monte Tronador, Northern Patagonia), providing the first frontal ablation estimates for a Patagonian glacier outside the icefields.Subseasonal frontal ablation time series were reconstructed for 2017-2024 and annual values for 2013-2023.Mean annual frontal ablation was ~3.6 Mm a, totaling 39.5 1.8 Mm (0.036 0.002 Gt, assuming 917 kg m) over 2013-2023.Frontal ablation shows marked seasonality and strong spatiotemporal variability, with hotspots migrating irregularly along the calving front, whereas ice velocity at the glacier terminus exhibits a stable spatial pattern.Frontal ablation correlates strongly with air temperature (r = 0.71) and lake level (r = 0.71), moderately with lake surface temperature (r = 0.63), and negatively with precipitation (r = -0.56).The method is particularly suited for high-resolution studies of mountain glaciers, where spatial variability and transient frontal processes dominate terminus dynamics. IntroductionPatagonia is a hotspot of ice loss in the Andes, accounting for over 80% of regional glacier mass loss (Braun and others, 2019; Dussaillant and others, 2019).This loss is concentrated in the Southern (SPI) and Northern Patagonian icefields (NPI), dominated by large calving outlet glaciers (Minowa and others, 2021).In these glaciers, frontal ablation encompassing iceberg calving and subaqueous melt drives highly non-linear glacier responses to climatic forcing and can partially decouple ice dynamics from climate (e.g., Pfeffer, 2007; Choi and others, 2018).Outside these icefields, frontal ablation remains unexplored.Northern Patagonia (35-45S) is characterized by warmer and less humid conditions, with winterdominated precipitation, unlike the year-round precipitation in Southern Patagonian Andes (45-53S) (Garreaud and others, 2013).Glaciers in Northern Patagonia develop smaller and shallower proglacial
Clavero et al. (Thu,) studied this question.