The role of supraglacial debris on the abaltion of the Khumbu Glacier was studied based on the observational data of ablation and heat exchange over the glacial surface in the summer monsoon of 1978. The glacier was classified into 4 areas according to the characteristics of supraglacial debris. In the measurement of ablation, a different method suitable for each area was employed. An average ablation rate of 2.5 cm/dy was obtained in the upper half of the ablation area where glacier flow is active, while in the lower stagnant area it is less than 0.4 cm/dy due to a heavy debris load. Shortterm heat budget observations have shown that the solar radiation is the main heat source for ablation. The relation between ablation and solar radiation was examined in two areas. Schistose debris with low albedo and thin concentration plays a major role in the enhancement of ablation.

HighlightsAn open-source atrial wall thickness CT and MRI dataset (n=20) with consensus ground truth obtained with statistical estimation from expert delineation (n=2).Exploring a range of metrics for evaluating and ranking wall segmentation and thickness algorithms (n=6), and benchmarks were set on each metric.New three-dimensional mean thickness atlases for atrial wall thickness derived from the consensus ground truth. The atlas was also transformed into a two-dimensional flat map of thickness.

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The mass budget of Khumbu Glacier is estimated on the basis of ablation observation at the lower part of the glacier. The accumulation is calculated assuming that there is uniform precipitation on the glacier surface. The total ablation from the glacier is more than triple of the accumulation by the snowfall on the glacier. Mass supply from the surrounding walls is necessary for the mass balance of the glacier. The latter is estimated to be more than double of the direct snowfall onto the glacier. This suggests the possibility that snowfall at 7000-8000m is of the same order as observed at 4000m.