Greenland ice sheet surface mass balance 1991–2000: Application of Polar MM5 mesoscale model and in situ data
Greenland ice sheet surface mass balance 1991–2000: Application of Polar MM5 mesoscale model and in situ data
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1991-2000年格陵兰冰盖表面质量平衡：Polar MM5中尺度模型和现场数据的应用
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
L. Bai
中科院分区：
文献类型：
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作者：
J. Box;D. Bromwich;L. Bai
[1] 宾夕法尼亚州立大学极地国家大气研究中心第五代中尺度模型 (Polar MM5) 区域气候模型于 1991 年至 2000 年在北大西洋地区运行。我们分析了格陵兰冰盖 24 公里的输出，以评估表面质量平衡及其子组成部分的空间和时间变化。该模型输出与来自 17 个站点的 3 年自动气象站 (AWS) 数据进行比较，以确定偏差。利用现场数据，我们对融化能量以及来自地表和吹雪的水蒸气通量的偏差进行了简单的修正。模拟的累积率与AWS和雪坑观测结果一致。使用建模的融化体积和融水保留方案来估算冰盖上的径流和表面质量平衡分布。根据所调查的十年，初步确定了表面质量平衡成分的年际变化幅度。最大的变化集中在冰盖边缘，那里的积累率和消融率都最大。模拟的年际波动表明总冰盖表面质量平衡存在很大的绝对变化，±187 km3 yr−1。模拟平衡线高度的变化表明南部的热变化占主导地位，随着纬度的增加，积累变化的重要性也随之增加。提出了表面质量平衡对温度和降水异常敏感性的经验函数。建议最大和最小表面能和质量通量的精确位置和区域。通过对冰山流量和底部融化的估计，冰盖总质量平衡估计为−78 km3 yr−1，在1991-2000年十年间导致海平面上升2.2毫米，占观测到的全球海平面上升（1.5毫米yr−1）的15%。更负的质量平衡归因于风雪升华损失和 20 世纪 90 年代的区域变暖。
[1] The Polar Pennsylvania State University–National Center for Atmospheric Research Fifth-Generation Mesoscale Model (Polar MM5) regional climate model was run over the North Atlantic region for 1991–2000. We analyze 24-km output over the Greenland ice sheet to evaluate spatial and temporal variability of the surface mass balance and its subcomponents. The model output is compared with 3 years of automatic weather station (AWS) data from 17 sites to identify biases. Using the in situ data, we derive simple corrections for biases in melt energy and in water vapor fluxes from the surface and from blowing snow. The simulated accumulation rate is in agreement with AWS and snow pit observations. Estimates for runoff and the surface mass balance distribution over the ice sheet are produced using modeled melt volume and a meltwater retention scheme. From the decade investigated, the magnitude of interannual variability in surface mass balance components is tentatively established. The largest variability is concentrated along the ice sheet margin, where both accumulation and ablation rates are largest. The simulated interannual fluctuations suggest a large absolute variability, ±187 km3 yr−1 for total ice sheet surface mass balance. Variability in simulated equilibrium line altitude is suggestive of a dominance of thermal variability in the south with increasing importance of accumulation variability with increasing latitude. Empirical functions for the sensitivity of surface mass balance to temperature and precipitation anomalies are presented. The precise locations and regions of maximum and minimum surface energy and mass fluxes are suggested. Using an estimate for iceberg discharge and bottom melting, the total ice sheet mass balance is estimated be −78 km3 yr−1, producing 2.2 mm of eustatic sea level rise over the 1991–2000 decade and contributing 15% to the observed (1.5 mm yr−1) global sea level rise. The more negative mass balance is attributed to including blowing-snow sublimation loss and to regional warming in the 1990s.