Thin and thinner : Ice mass balance measurements during SHEBA
Thin and thinner : Ice mass balance measurements during SHEBA
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越来越薄：SHEBA 期间的冰质量平衡测量
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
H. Eicken
中科院分区：
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作者：
D. Perovich;C. Grenfell;J. Richter;B. Light;W. Tucker;H. Eicken
作为北冰洋表面热量收支（SHEBA）大型跨学科研究的一部分，我们安装了超过135个冰厚计来确定海冰质量平衡。在1997年秋季安装这些测量仪时，我们发现大部分多年冰层只有1米厚，比预期的要薄得多。在长达一年的实地实验过程中，我们监测了各种冰类型的质量平衡，包括第一年冰，积水冰，无积水冰，多年冰，驼峰，新的山脊，老山脊。这些地点的初始冰厚度从0.3米到8米不等，积雪深度从几厘米到一米多不等。然而，尽管这些测厚地点有着各种各样的差异和变化，但它们有一个共同的特点：在SHEBA年，每个地点的冰层都净变薄。1997年10月发现的薄冰在1998年10月更薄。冰厚度的年周期在所有地点也是相似的。整个冬天，厚度稳步增加，到了春天逐渐减少。随后在夏季融化期间厚度急剧下降，在夏末和初秋开始冻结时又逐渐变小。最大的表面融化是在7月，而底部消融在8月达到高峰。结合从网站的结果，我们发现，平均冬季增长0.51米，夏季融化1.26米，其中包括0.64米的表面融化和0.62米的底部融化。有一个较厚的冰有一个微弱的趋势，冬季增长较少，净损失较大的一年;然而，冰的增长也受到积雪深度的影响。在吸积和消融部位之间观察到相当大的变异性。在9个月的生长季节的总增长范围从零厚脊冰超过一米的年轻的冰。池塘往往有大量的表面融化，而山脊有相当大的底部消融。大尺度大气环流模式表明，北极海冰可能是气候变化的一个敏感指标，复杂的大气-海冰-海洋相互作用的细节还没有得到很好的理解（Spelman和Manabe，1984年;华盛顿和Meehl，1986年; Dickinson等人，1987; Ingram等人，1989;莫里茨等人，1993; Jin等人，1994; Rind等人，1995; Battisti等人，1997年）。这种潜在的重要性和有限的理解的结合提供了一个大型跨学科研究的动机，称为北冰洋表面热收支（SHEBA）。SHEBA的主要目标是：1）确定控制冰量和云辐射反馈机制的冰-海洋-大气过程; 2）开发改进大气环流模型中北极气候模拟的模型（莫里茨等人，1993;莫里茨和Perovich，1996）。SHEBA的一个中心组成部分是从1997年10月到1998年10月的一年之久的田间实验（Perovich等人，1999年a），旨在获得高质量，全面，综合的数据集，定义了整个年度周期的大气，冰和海洋的状态。由于冰本质上是冰表面和冰底部热量收支的一个大积分器，
As part of a large interdisciplinary study of the surface heat budget of the Arctic Ocean (SHEBA), we installed more than 135 ice thickness gauges to determine the sea ice mass balance. While installing these gauges during the fall of 1997, we found that much of the multiyear ice cover was only 1 m thick, considerably thinner than expected. Over the course of the year-long field experiment we monitored the mass balance for a wide variety of ice types, including firstyear ice, ponded ice, unponded ice, multiyear ice, hummocks, new ridges, and old ridges. Initial ice thicknesses for these sites ranged from 0.3 to 8 m, and snow depths varied from a few centimeters to more than a meter. However, for all of their differences and variety, these thickness gauges sites shared a common trait: at every site there was a net thinning of the ice during the SHEBA year. The thin ice found in October 1997 was even thinner in October 1998. The annual cycle of ice thickness was also similar at all sites. There was a steady increase in thickness through the winter that gradually tapered off in the spring. This was followed by a steep dropoff in thickness during summer melt and another tapering in late summer and early fall as freezeup began. Maximum surface melting was in July, while bottom ablation peaked in August. Combining results from the sites, we found an average winter growth of 0.51 m and a summer melt of 1.26 m, which consisted of 0.64 m of surface melt and 0.62 m of bottom melt. There was a weak trend for thicker ice to have less winter growth and greater net loss for the year; however, ice growth was also impacted by the snow depth. Considerable variability was observed between sites in both accretion and ablation. The total accretion during the 9-month growth season ranged from zero for thick ridged ice to more than a meter for young ice. Ponds tended to have a large amount of surface melting, while ridges had considerable bottom ablation. INTRODUCTION Large-scale general circulation models indicate that Arctic sea ice may be a sensitive indicator of climate change and that the details of the complex atmosphereice-ocean interaction are not well understood (Spelman and Manabe, 1984; Washington and Meehl, 1986; Dickinson et al., 1987; Ingram et al., 1989; Moritz et al., 1993; Jin et al., 1994; Rind et al., 1995; Battisti et al., 1997). This combination of potential importance and limited understanding provided the motivation for a large interdisciplinary study called the Surface Heat Budget of the Arctic Ocean (SHEBA). The primary goals of SHEBA are 1) to determine the ice-ocean-atmosphere processes that control the icealbedo and cloud radiation feedback mechanisms and 2) to develop models that improve simulations of Arctic climate in general circulation models (Moritz et al., 1993; Moritz and Perovich, 1996). A central component of SHEBA was a year-long field experiment from October 1997 through October 1998 (Perovich et al., 1999a) directed at acquiring a high-quality, comprehensive, integrated data set that defined the state of the atmosphere, ice, and ocean over an entire annual cycle. Since the ice is, in essence, a grand integrator of the heat budget at the surface and bottom of the ice, an