Micrometeorological conditions and surface mass and energy fluxes on Lewis Glacier, Mt Kenya, in relation to other tropical glaciers
Micrometeorological conditions and surface mass and energy fluxes on Lewis Glacier, Mt Kenya, in relation to other tropical glaciers
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DOI：
10.5194/tc-7-1205-2013
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发表时间：
2012-12
期刊：
影响因子：
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通讯作者：
L. Nicholson;R. Prinz;T. Mölg;G. Kaser
中科院分区：
文献类型：
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作者：
L. Nicholson;R. Prinz;T. Mölg;G. Kaser
抽象的。肯尼亚山上的刘易斯冰川是研究得最好的热带冰川之一，但由于缺乏长期气象数据，对冰川物质平衡及其气候驱动因素的相互作用的充分了解受到阻碍。在这里，我们提出了从2009年10月到2012年2月从冰川表面收集的2.5年的气象数据。测量位置位于刘易斯冰川的上部，但该位置经历了负的年度质量平衡，其条件与内热带南美洲冰川下部消融区的条件相当。在赤道东非的其他冰川山脉的背景下，肯尼亚山的山顶区域显示出强烈的对流云发展的昼夜周期，而不是鲁文佐里斯，那里的云层覆盖持续整个昼夜周期，和基利曼哈罗，那里晴朗的天空占上风。地面能量通量计算的气象站网站使用物理质量和能量平衡模型驱动的测量气象数据和其他输入参数，由蒙特卡洛优化。升华率低于其他热带冰川的报告，全年融化率很高，冰川表面几乎每天都达到熔点。地表物质平衡受固体降水和气温的影响，辐射为地表提供了最大的净能量来源。与晴朗的天空条件相比，云层通常会减少净辐射平衡，因此，肯尼亚山山顶频繁形成对流云以及相关的较高积雪率对于限制冰川表面的质量损失率非常重要。这里所示的分析形成了未来冰川范围内的质量和能量平衡建模的基础，以确定肯尼亚山冰川提供的气候代理。
Abstract. The Lewis Glacier on Mt Kenya is one of the best-studied tropical glaciers, but full understanding of the interaction of the glacier mass balance and its climatic drivers has been hampered by a lack of long-term meteorological data. Here we present 2.5 yr of meteorological data collected from the glacier surface from October 2009 to February 2012. The location of measurements is in the upper portion of Lewis Glacier, but this location experiences negative annual mass balance, and the conditions are comparable to those experienced in the lower ablation zones of South American glaciers in the inner tropics. In the context of other glaciated mountains of equatorial East Africa, the summit zone of Mt Kenya shows strong diurnal cycles of convective cloud development as opposed to the Rwenzoris, where cloud cover persists throughout the diurnal cycle, and Kilimanjaro, where clear skies prevail. Surface energy fluxes were calculated for the meteorological station site using a physical mass- and energy-balance model driven by measured meteorological data and additional input parameters that were determined by Monte Carlo optimization. Sublimation rate was lower than those reported on other tropical glaciers, and melt rate was high throughout the year, with the glacier surface reaching the melting point on an almost daily basis. Surface mass balance is influenced by both solid precipitation and air temperature, with radiation providing the greatest net source of energy to the surface. Cloud cover typically reduces the net radiation balance compared to clear-sky conditions, and thus the frequent formation of convective clouds over the summit of Mt Kenya and the associated higher rate of snow accumulation are important in limiting the rate of mass loss from the glacier surface. The analyses shown here form the basis for future glacier-wide mass and energy balance modeling to determine the climate proxy offered by the glaciers of Mt Kenya.