Air Temperature Characteristics, Distribution, and Impact on Modeled Ablation for the South Patagonia Icefield
Air Temperature Characteristics, Distribution, and Impact on Modeled Ablation for the South Patagonia Icefield
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DOI：
10.1029/2018jd028857
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发表时间：
2019-01-27
影响因子：
4.4
通讯作者：
Silva, A.
中科院分区：
文献类型：
--
作者：
Bravo, C.;Quincey, D. J.;Silva, A.
巴塔哥尼亚的冰川是南美洲最大的冰川，正在迅速萎缩，这引起了人们对在持续气候变化的情况下它们对海平面上升的贡献的担忧。然而，预测未来冰川衰退的建模研究受到测量的冰川上的空气温度的稀缺性的限制，因此倾向于使用空间和时间上恒定的递减率。本研究提供了9个月的气温观测资料。该网络由五个自动气象站和三个冰川上的空气温度传感器安装在南巴塔哥尼亚冰原沿着一个样带在48度45 S。总的来说，观测到的直减率在东部（-0.0072摄氏度/米）比西部（-0.0055摄氏度/米）更陡，并且在冰川的下部（舌，消融区）和上部（高原，堆积区）之间变化。在海拔相似的地区，东部的冰川外温度高于西部。然而，对冰川的观测表明，与西部相比，东部的冰川冷却效果更高。通过分布式温度指数和点尺度能量平衡模型的应用，我们表明，模拟消融率变化高达60%，取决于空气温度外推法应用，融化被高估和升华被低估，如果冰川冷却效应不包括在分布式的空气温度数据。这些结果可以改善当前和未来的模拟工作的能量和质量平衡的整个南巴塔哥尼亚冰原。
The glaciers of Patagonia are the largest in South America and are shrinking rapidly, raising concerns about their contribution to sea level rise in the face of ongoing climatic change. However, modeling studies forecasting future glacier recession are limited by the scarcity of measured on-glacier air temperatures and thus tend to use spatially and temporally constant lapse rates. This study presents 9months of air temperature observations. The network consists of five automatic weather stations and three on-glacier air temperature sensors installed on the South Patagonia Icefield along a transect at 48 degrees 45S. Observed lapse rates are, overall, steeper on the east (-0.0072 degrees C/m) compared to the west (-0.0055 degrees C/m) and vary between the lower section (tongue, ablation zone) and the upper section (plateau, accumulation zone) of the glaciers. Warmer off-glacier temperatures are found in the east compared to the west for similar elevations. However, on-glacier observations suggest that the glacier cooling effect is higher in the east compared to the west. Through application of distributed temperature-index and point-scale energy balance models we show that modeled ablation rates vary by up to 60%, depending on the air temperature extrapolation method applied, and that melt is overestimated and sublimation is underestimated if the glacier cooling effect is not included in the distributed air temperature data. These results can improve current and future modeling efforts of the energy and mass balance of the whole South Patagonia Icefield.