Observation and Parameterization of Ablation at the Base of Ronne Ice Shelf, Antarctica
Observation and Parameterization of Ablation at the Base of Ronne Ice Shelf, Antarctica
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DOI：
10.1175/2010jpo4317.1
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发表时间：
2010-10-01
影响因子：
3.5
通讯作者：
Corr, Hugh F. J.
中科院分区：
文献类型：
--
作者：
Jenkins, Adrian;Nicholls, Keith W.;Corr, Hugh F. J.
通过冰架下面的海洋边界层的湍流传输的参数是用直接测量的底部烧蚀来检验的。观测是在罗恩冰架西南部进行的，距离开阔水域约500公里。使用相敏雷达记录冰架变薄的情况，在一个月和一年的时间内测量了平均基础消融率。在雷达观测期间，观测到冰架底部约25m范围内的海洋温度，而潮汐主导洋流是通过对较早时期的配置流观测进行潮汐分析而估计的。利用这些海洋数据和边界层内湍流传输的一些总体参数计算出的烧蚀率与直接测量结果进行了比较。使用明确包括洋流对热量和盐的湍流传输的影响的参数化导出的烧蚀率与观测值匹配到40%以内；通过适当调整阻力系数，失配可以减少到观测误差水平以下。用两种稍简单的、依赖于电流的、使用恒定湍流传递系数的参数化方法也能获得同样好的一致性，并给出了罗恩冰架上这一特定位置的系数的最佳值。
Parameterizations of turbulent transfer through the oceanic boundary layer beneath an ice shelf are tested using direct measurements of basal ablation. Observations were made in the southwestern part of Ronne Ice Shelf, about 500 km from open water. The mean basal ablation rate was measured over a month-long and a year-long period using phase-sensitive radar to record the thinning of the ice shelf. Ocean temperatures were observed within about 25 m of the ice shelf base over the period of the radar observations, while the tidally dominated ocean currents were estimated from tidal analysis of collocated current observations from an earlier period. Ablation rates derived using these ocean data and a number of bulk parameterizations of turbulent transfer within the boundary layer are compared with the direct measurements. The ablation rates derived using a parameterization that explicitly includes the impact of ocean currents on the turbulent transfer of heat and salt match the observations to within 40%; with suitable tuning of the drag coefficient, the mismatch can be reduced below the level of the observational errors. Equally good agreement can be obtained with two slightly simpler, current-dependent parameterizations that use constant turbulent transfer coefficients, and the optimal values for the coefficients at this particular location on Ronne Ice Shelf are given.