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首页> 外文学位 >Characteristics of cloud cover and its radiative impacts over the high elevations of the Greenland ice sheet.
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Characteristics of cloud cover and its radiative impacts over the high elevations of the Greenland ice sheet.

机译：格陵兰冰盖高海拔地区的云层特征及其辐射影响。

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摘要

Understanding the effects of clouds on the surface energy balance is a necessary part of understanding the controls on the mass balance of the Greenland ice sheet. Clouds have an enhanced role in governing the surface energy balance in dry polar atmospheres, yet their frequency, thermodynamic properties and radiative properties are poorly quantified over Greenland. In response to this important data gap, this research quantifies cloud occurrence and cloud radiative effects over the high plateau of Greenland using a unique new cloud data set. This data set is comprised of ground-based, high frequency cloud sky fraction and height measurements and high accuracy surface radiation measurements. Combined, they permit an unprecedented level of detail in the evaluation of the net radiative effect of cloud cover at the surface. This research also employs the MODIS cloud mask data set (MOD35) to quantify cloud frequency for a four-year period (March 2000--2004) over the high plateau of the Greenland ice sheet. This research contributes to our understanding the cloud climate of the high plateau of the Greenland ice sheet and the role of clouds in the surface energy balance in this environment. Both are useful contributions for improving regional climate modeling of Greenland.; The results of this research demonstrated that MOD35 is a useful tool for assessing cloud cover frequency over Greenland. During daylight hours, the accuracy of the cloud mask ranged from -7 to +12%. Using MOD35, this research showed that May is the most cloud free month of the year (27%) while August, excluding the winter range of errors, is the cloudiest (55%). Using high resolution radiation and cloud measurements, this research found that the radiative impact of clouds is positive for all hours of the day and all months of the year at Summit. Comparing hourly GC-Net radiation data and MOD35 cloud data, this research showed that the net radiative effect of clouds ranges from -20 W/m2 to 35 W/m2 over the high elevations of the Greenland ice sheet at midday during JJA. The strongest negative impact is found over South Dome; the strongest positive impact is found over NE Greenland.
机译：了解云对表面能平衡的影响是了解控制格陵兰冰原质量平衡的必要步骤。在干燥的极地大气中，云在控制表面能平衡方面起着增强的作用，但是在格陵兰岛上，它们的频率，热力学性质和辐射性质很难量化。针对这一重要的数据缺口，本研究使用独特的新云数据集对格陵兰高原高原的云发生和云辐射效应进行了量化。该数据集包括基于地面的高频云天空分数和高度测量以及高精度表面辐射测量。结合起来，它们在评估云层表面的净辐射效应时提供了前所未有的细节水平。这项研究还利用MODIS云遮罩数据集（MOD35）量化了格陵兰冰原高原期四年（2000年3月--2004年）的云频率。这项研究有助于我们了解格陵兰冰原高原高原的云气候，以及云在这种环境中在表面能平衡中的作用。两者都是对改善格陵兰地区气候模拟的有益贡献。这项研究的结果表明，MOD35是评估格陵兰岛云量的有用工具。在白天，防云罩的准确性范围为-7至+ 12％。使用MOD35，这项研究表明5月是一年中最无云的月份（27％），而8月（不包括冬季误差范围）是最多云的（55％）。通过使用高分辨率辐射和云测量，这项研究发现在Summit的一天中的所有小时和一年中的所有月份，云的辐射影响都是正的。比较每小时的GC-Net辐射数据和MOD35云数据，这项研究表明，在JJA中午，格陵兰冰原的高海拔地区，云的净辐射效应范围从-20 W / m2到35 W / m2。对南穹顶的负面影响最大。在格陵兰岛东北部发现了最强烈的积极影响。

著录项

  • 作者

    Starkweather, Sandra M.;

  • 作者单位

    University of Colorado at Boulder.;

  • 授予单位 University of Colorado at Boulder.;
  • 学科 Physical Geography.; Physics Atmospheric Science.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 202 p.
  • 总页数 202
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 自然地理学;大气科学（气象学）;
  • 关键词

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