SNOW COVER AND SEA-ICE SENSITIVITY TO GENERIC CHANGES IN EARTH ORBITAL PARAMETERS
SNOW COVER AND SEA-ICE SENSITIVITY TO GENERIC CHANGES IN EARTH ORBITAL PARAMETERS
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DOI：
10.1029/94jd02686
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发表时间：
1995-01-20
影响因子：
4.4
通讯作者：
KUTZBACH, JE
中科院分区：
文献类型：
--
作者：
GALLIMORE, RG;KUTZBACH, JE
一个低分辨率的大气环流模式被用来研究地球自转角（倾角增加3度）和岁差（夏季与冬季近日点结合大偏心率（0.04））的大变化对高纬度气候的单独和综合影响。轨道变化，包括过去150，000年的极端情况，使北方夏季（冬季）辐射显著增加（减少）。倾斜的增加导致海冰的减少比岁差变化大得多。年平均海冰厚度和秋季海冰覆盖率分别减少50%和41%（21%和0%）的倾斜增加（岁差变化）。更大的垂直度效应是一个结果，增强的年平均辐射与倾斜的增加，海冰在岁差实验中的适度响应是由于季节性的相互作用模型海冰的增长和融化和传热过程之间的关系通过冰。在倾斜度增加的实验中，冬季日照减少，夏季与冬季近日点相比，从秋季到早春，北方大陆的积雪面积增加了15%。大陆上的平均积雪深度增加（20%），只有从冬季到夏季近日点的变化，因为更长的积雪季节。在春末和夏季，增强的辐射（在增加倾斜和夏季近日点的实验中）迅速融化了积雪，因此它不会像在减少夏季日照（冬季近日点和减少倾斜）的实验中那样持续到夏季。实验表明，春季和夏季辐射的轨道减少可能是加拿大东北部冰川形成的一个重要因素。无积雪季节的持续时间被发现减少非线性减少春夏日照。从现代到115，000年B. P.轨道条件的变化使加拿大东北部的无雪季节减少了3-4周。对于一个更夸张的倾斜（20度）和偏心率（0.06），雪原偶尔幸存的夏季。总体而言，模型结果表明，115，000年BP时的轨道条件极大地增加了加拿大东北部上空常年雪原的可能性。
A low-resolution general circulation model is used to examine the separate and combined effects on high-latitude climate of large changes in Earth's obliquity (3 degrees tilt angle increase) and precession (summer versus winter perihelion in conjunction with large eccentricity (0.04)). The orbital changes, encompassing the extremes for the past 150,000 years, produced significantly increased (decreased) northern summer (winter) radiation. Increased tilt caused a much greater reduction in sea ice than the precessional change. The decreases in annual mean sea ice thickness and fall sea ice coverage are respectively 50% and 41% (21% and 0%) for the tilt increase (precessional change). The larger obliquity effect is a consequence of enhanced annual mean radiation with tilt increase; the modest response of sea ice in the precessional experiments is attributed to a seasonal interaction between processes governing model sea ice growth and melt and heat transfer through the ice. The reduced winter insolation in the experiments with increased tilt and summer versus winter perihelion produced colder conditions and up to 15% greater areal coverage of snow over the northern continents from fall to early spring. The average depth of snow on the continents increased (by 20%) only with the change from winter to summer perihelion because of a greater length of the snow accumulation season. During late spring and summer, enhanced radiation (in the experiments with increased tilt and summer perihelion) rapidly melted the snowpack so that it did not persist as long into the summer season as in the experiments with reduced summer insolation (winter perihelion and decreased tilt). The experiments indicate that orbital reduction of spring-summer radiation could be an important factor in initiating glaciation over northeastern Canada. The duration of the snow cover-free season was found to decrease nonlinearly with decreased spring-summer insolation. The change from modern to 115,000 year B.P. orbital conditions reduced the snow cover-free season over northeastern Canada by 3-4 weeks. For a more exaggerated tilt (20 degrees) and eccentricity (0.06), snowfields occasionally survived the summer season. Overall, the model results suggest that the orbital conditions at 115,000 years B.P. greatly enhanced the likelihood of perennial snowfields over northeastern Canada.