The annual cycle of snowfall at Summit, Greenland
The annual cycle of snowfall at Summit, Greenland
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格陵兰萨米特的年度降雪周期
DOI：
10.1002/2015jd023072
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
B. Sheppard
中科院分区：
文献类型：
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作者：
Benjamin B. Castellani;M. Shupe;D. Hudak;B. Sheppard
虽然对格陵兰中部的积雪积累进行了广泛的研究，但由于缺乏观测，该地区降雪的年际变化尚未得到很好的了解。格陵兰峰顶的能量、云、大气状态和峰顶降水综合表征（ICECAPS）项目提供了一个独特的、基于地面的机会来研究地表物质平衡为正的格陵兰中部降水。结合降水发生传感器系统（POSS）、毫米波云雷达（MMCR）和雪桩场的数据，研究了峰顶降水的年周期。6月至10月的日平均降雪量是11月至5月的3倍，而在同一时间段内，地表高度变化仅比11月至5月高15%。地表高度变异性的减少可以用潜热通量、压实和风的贡献的季节变化性质来解释。ICECAPS的遥感数据和实地测量数据在年总水当量方面并不一致。这种差异可能是由于POSS和MMCR在峰顶的降雪检索中偏差较小。为了进一步研究季节循环，POSS的降雪测量与当地气象参数有关，包括风向、液态水路径（LWP）、2米温度和可降水量。观测到的风向和湿度依赖性与降雪与来自附近无冰海洋的潮湿空气脉冲相一致，这种资源在冬季海冰消退时在夏季变得更容易获得。LWP与降雪的关系不大，这表明冰相降水过程对峰顶的降雪非常重要。
While snow accumulation over central Greenland has been extensively studied, interannual variability of snowfall in the region is not well understood due to a dearth of observations. The Integrated Characterization of Energy, Clouds, Atmospheric state and Precipitation at Summit (ICECAPS) project at Summit, Greenland, offers a unique, ground‐based opportunity to study precipitation in central Greenland where the surface mass balance is positive. Combining data from a Precipitation Occurrence Sensor System (POSS), Millimeter‐wavelength Cloud Radar (MMCR), and snow stake field, the annual cycle of precipitation at Summit is examined. Average daily snowfall is higher by a factor of 3 from June to October compared to November to May, while surface height change is only higher by 15% during the same timeframes. This reduced variability in surface height is explained by the seasonally varying nature of latent heat flux, compaction, and wind contributions. The ICECAPS remote sensors and stake field measurements do not agree as far as total annual water equivalent. This discrepancy is likely due to a low bias in the POSS and MMCR snowfall retrievals for Summit. To further examine the seasonal cycle, snowfall measurements by the POSS were linked to local meteorological parameters, including wind direction, liquid water path (LWP), 2 m temperature, and precipitable water vapor. An observed wind direction and moisture dependence are consistent with snowfall being linked to pulses of moist air that originate over nearby, ice‐free ocean, a resource that becomes more readily available in summertime as the winter sea ice retreats. LWP is shown to have little relationship to snowfall, indicating that ice‐phase precipitation processes are quite important for snowfall at Summit.