Multidecadal Basal Melt Rates and Structure of the Ross Ice Shelf, Antarctica, Using Airborne Ice Penetrating Radar
Multidecadal Basal Melt Rates and Structure of the Ross Ice Shelf, Antarctica, Using Airborne Ice Penetrating Radar
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DOI：
10.1029/2019jf005241
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发表时间：
2020-03
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通讯作者：
I. Das;L. Padman;R. Bell;H. Fricker;K. Tinto;C. Hulbe;C. Siddoway;T. Dhakal;N. Frearson;C. Mosbeux;S. Cordero;M. Siegfried
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作者：
I. Das;L. Padman;R. Bell;H. Fricker;K. Tinto;C. Hulbe;C. Siddoway;T. Dhakal;N. Frearson;C. Mosbeux;S. Cordero;M. Siegfried
冰架底部融化是南极冰盖质量损失的主要来源。对冰架底部融化速率的现场测量很少，而更广泛的卫星测高估计需要有关积雪密度和近地表层特征的精确信息。我们描述了一种新的方法来估计几十年的基础融化率使用机载冰穿透雷达数据在罗斯冰架的3年调查期间获得。这些数据揭示了一个具有明显的上部和下部单元的冰柱，其厚度随着冰从接地线向冰锋流动而变化。我们解释为大陆流冰，已流过接地线和上单位的冰降雪形成的相对平坦的冰架上的较低的单位。我们使用冰厚度差异和应变引起的厚度变化的调查线之间的较低的单位，结合冰的速度，推导出平均超过一个到六十年的基础融化率。我们的研究结果与2003-2009年期间的卫星激光测高估计相似，表明罗斯冰架的融化速率几十年来一直相当稳定。我们确定了五个地点的基础融化率升高，在0.5-2米a-1的范围内，靠近冰架前。这些热点表明了进入冰架下海洋空腔的温暖海水的路径，可能是夏季变暖的南极地表水和修改的环极深水的组合，如果海洋变暖，这些热点是冰架弱化的潜在区域。
Basal melting of ice shelves is a major source of mass loss from the Antarctic Ice Sheet. In situ measurements of ice shelf basal melt rates are sparse, while the more extensive estimates from satellite altimetry require precise information about firn density and characteristics of near‐surface layers. We describe a novel method for estimating multidecadal basal melt rates using airborne ice penetrating radar data acquired during a 3‐year survey of the Ross Ice Shelf. These data revealed an ice column with distinct upper and lower units whose thicknesses change as ice flows from the grounding line toward the ice front. We interpret the lower unit as continental meteoric ice that has flowed across the grounding line and the upper unit as ice formed from snowfall onto the relatively flat ice shelf. We used the ice thickness difference and strain‐induced thickness change of the lower unit between the survey lines, combined with ice velocities, to derive basal melt rates averaged over one to six decades. Our results are similar to satellite laser altimetry estimates for the period 2003–2009, suggesting that the Ross Ice Shelf melt rates have been fairly stable for several decades. We identify five sites of elevated basal melt rates, in the range 0.5–2 m a−1, near the ice shelf front. These hot spots indicate pathways into the sub‐ice‐shelf ocean cavity for warm seawater, likely a combination of summer‐warmed Antarctic Surface Water and modified Circumpolar Deep Water, and are potential areas of ice shelf weakening if the ocean warms.