了解温度对格伦的流率的影响因素= (T)和为什么我们=常数-地球科学堆栈交换江南电子竞技平台江南体育网页版 最近30从www.hoelymoley.com 2023 - 05 - 31 - t04:08:11z //www.hoelymoley.com/feeds/question/25161 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/25161 2 了解温度对格伦的流率的影响因素= (T)和为什么我们=常数 k12345 //www.hoelymoley.com/users/28536 2023 - 05 - 02 - t18:21:13z 2023 - 05 - 05 - t14:39:00z < p >我想更好地理解为什么我看到如此多的人选择一个固定值< span class = " math-container " > < / span >美元美元格伦流定律在冰川建模。我发现使用一个简单的阿列纽斯关系得到的公式< / p > < p > <跨类= " math-container " > (T) =美元\离开(A_0 exp \左(\压裂{q} {R (T -β\ p)} \) \右)< / span >美元(从12页< a href = " https://www.researchgate.net/publication/267748557_Simulating_the_climatic_response_of_Hardangerjokulen_in_southern_Norway_since_the_Little_Ice_Age_Master%27s_thesis_in_Earth_Science " rel = " nofollow noreferrer " > < / >源)< / p > < p >这个公式意味着温度影响的价值< span class = " math-container " > < / span >美元美元,所以我认为会有一个不同的类< span = " math-container " > < / span >美元美元在冰川内不同深度。然而,我也发现,我们通常不会在冰川内不同深度温度数据。这表明,我们不能用上面的函数来计算< span class = " math-container " >一个(T) < / span >美元在冰川内不同深度。这< / p > < p > < a href = " https://glaciers.gi.alaska.edu/sites/default/files/Notes_thermodynamics_Aschwanden.pdf " rel = " nofollow noreferrer " > < / >来源(页1)使它看起来像我们只是选择一个类型的热结构的冰川(冷,温带,或多种燃料的),然后使用它来确定常数我们应该选择<跨类= " math-container " > < / span >美元美元。< / p > < ul > <李>为什么修复类< span = " math-container " > < / span >美元美元是一个常数看作一个准确的方法如果< span class = " math-container " > < / span >美元美元严重取决于温度?手头的冰川的热结构(冷,温带,或多种燃料的)真的给我们足够的信息来准确地修复类< span = " math-container " > < / span >美元美元是一个恒定值?< /李> < / ul > < p >任何作者和关键短语为寻找更多这方面的信息,我们将不胜感激。< / p > < p >任何信息我将非常感谢。我很新。< / p > //www.hoelymoley.com/questions/25161/-/25167 # 25167 0 答案由彼得·简颂了解温度对格伦的流率的影响因素= (T)和为什么我们=常数 彼得很 //www.hoelymoley.com/users/81 2023 - 05 - 05 - t14:39:00z 2023 - 05 - 05 - t14:39:00z < p >格伦流定律是一个经验法则来源于现场和实验数据(格伦1955)。其原始形式的格伦表示法律< span class = " math-container " > $ $ \点\ varepsilon = B \ exp {(Q / RT)} \ nσ^ $ $ < / span >, < span class = " math-container " > \点\ varepsilon < / span >美元变形率,< span class = " math-container " > B美元< / span > <跨类= " math-container " >问美元< / span >和<跨类= " math-container " > n < / span >美元经验常数,< span class = " math-container " > R < / span >美元是气体常数和<跨类= " math-container " > T < / span >是美元的绝对温度。本配方介绍温度变形的依赖。< / p > < p >经验常数<跨类= " math-container " > n < / span >美元通常被视为是<跨类=“math-container”> = 3 < / span >美元但这基本上是一个平均的各种实验结果。Goldsby(2009)表明,< span class = " math-container " > n < / span >美元可以更小和更大的不同如果压力非常低或高,分别。米尔斯坦et al。(2022)表明,应力的依赖可能比之前认为的更大的<跨类= " math-container " > n \大约4.1美元< / span >快速流动的地区的冰盖。< / p > < p >粘度参数<跨类= " math-container " > < / span >美元美元(<跨类= " math-container " > B < /跨度>格伦的美元符号)会随冰温度如上图所示。然而,粘度参数也是敏感的一些其他参数如压力,晶体大小和形状,在冰晶体取向、杂质(1976年麻醉品和威廉姆森,1981年胡克,小巷1992)。因此粘度参数可以被视为网站具体。< / p > < p >显然B的值可能无法预测,除非大量的信息是了解冰川冰在整个身体。所以做处理的方法之一是使用粘度参数调优参数。 Usually this involves comparing model output with measured velocities. This approach has been implemented in many different ways by modellers of glaciers and ice sheets. In models with a thermodynamic component the flow law may still include a temperature dependence.

In the review by Hooke (1981) it also seems clear that laboratory and field experiments yielding the empirical constants $A$ and $n$ diverge. One reason for this is that small laboratory specimens of ice yield values that are not fully representative of natural conditions.

So, the final comment is that using a single value of A is a last resort when the complexity of the natural ice cannot be accommodated in calculations or models. The value of $A$ is still site specific and not generally transferable between glaciers or sites on glaciers. In the end the use of solution for the flow law depends on what is "good enough" for the problem to be solved.

References

Alley R, 1992. Flow-law hypotheses for ice-sheet modeling. Journal of Glaciology, 38(129), 245-256. doi:10.3189/S0022143000003658

Glen JW, 1955. The creep of polycrystalline ice. Proceedings of the Royal Society, Series A228 519–538. https://doi.org/10.1098/rspa.1955.0066

Goldsby D, 2009. Superplastic flow of ice relevant to glacier and ice-sheet mechanics. In Knight P, (ed.) Glacier Science and Environmental Change. Oxford: Wiley-Blackwell, 527pp. https://doi.org/10.1002/9780470750636.ch60

Gow AJ and Williamson T, 1976. Rheological implications of the internal structure and crystal fabrics of the West Antarctic ice sheet as revealed by deep core drilling at Byrd Station. Geological Society of America Bulletin, 87, 1665–1677.

Hooke RLeB, 1981. Flow law for polycrystalline ice in glaciers: comparison of theoretical predictions, laboratory data, and field measurements. Reviews of Geophysics and Space Physics, 19(4), 664–672. https://doi.org/10.1029/RG019i004p00664

Millstein JD, Minchew BM and Pegler SS, 2022. Ice viscosity is more sensitive to stress than commonly assumed. Commun Earth Environ 3, 57. https://doi.org/10.1038/s43247-022-00385-x
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