Testing the accuracy of a 1‐D volcanic plume model in estimating mass eruption rate
Testing the accuracy of a 1‐D volcanic plume model in estimating mass eruption rate
复制标题
测试一维火山羽流模型在估计大规模喷发率方面的准确性
DOI：
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发表时间：
2014
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通讯作者：
L. Mastin
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作者：
L. Mastin
在火山喷发期间，人们利用经验关系从烟柱高度来估算质量喷发速率。尽管这种方法简单，但这些关系可能不准确，并且在有风的条件下可能会低估速率。一维烟柱模型可以纳入大气条件，从而有可能给出更准确的估算值。在此，我提出了一个适用于侧风环境下烟柱的一维模型，并对25次历史火山喷发进行了模拟，这些喷发的烟柱高度\(H_{obs}\)得到了很好的观测，并且质量喷发速率\(M_{obs}\)可以根据绘制的沉积物质量和观测到的持续时间来计算。模拟过程考虑了风、温度和水的相变。大气条件是从美国国家大气研究中心再分析2.5°模型中获取的。模拟计算出了符合烟柱高度的最小值、最大值和平均值（\(M_{min}\)、\(M_{max}\)和\(M_{avg}\)）。喷发速率也通过经验公式\(M_{empir}=140H_{obs}^{4.14}\)（\(M_{empir}\)的单位是千克每秒，\(H_{obs}\)的单位是千米）进行了估算。对于这些喷发，在对数空间中，\(M_{avg}\)的残差标准误差约为0.53，\(M_{empir}\)的残差标准误差约为0.50。因此，对于这个数据集，该模型在预测\(M_{obs}\)方面比经验曲线的准确性略低。这个模型无法提高喷发速率估算的准确性，可能是因为即使是观测良好的烟柱高度其准确性也有限，模型公式不准确，或者是所研究的大多数喷发受风力影响不大。对于2010年4月14 - 18日在埃亚菲亚德拉冰盖火山的低矮、被风吹动的烟柱（这里有准确的烟柱高度时间序列），模拟速率与\(M_{obs}\)的吻合度确实比\(M_{empir}\)更好。
During volcanic eruptions, empirical relationships are used to estimate mass eruption rate from plume height. Although simple, such relationships can be inaccurate and can underestimate rates in windy conditions. One‐dimensional plume models can incorporate atmospheric conditions and give potentially more accurate estimates. Here I present a 1‐D model for plumes in crosswind and simulate 25 historical eruptions where plume height Hobs was well observed and mass eruption rate Mobs could be calculated from mapped deposit mass and observed duration. The simulations considered wind, temperature, and phase changes of water. Atmospheric conditions were obtained from the National Center for Atmospheric Research Reanalysis 2.5° model. Simulations calculate the minimum, maximum, and average values (Mmin, Mmax, and Mavg) that fit the plume height. Eruption rates were also estimated from the empirical formula Mempir = 140Hobs4.14 (Mempir is in kilogram per second, Hobs is in kilometer). For these eruptions, the standard error of the residual in log space is about 0.53 for Mavg and 0.50 for Mempir. Thus, for this data set, the model is slightly less accurate at predicting Mobs than the empirical curve. The inability of this model to improve eruption rate estimates may lie in the limited accuracy of even well‐observed plume heights, inaccurate model formulation, or the fact that most eruptions examined were not highly influenced by wind. For the low, wind‐blown plume of 14–18 April 2010 at Eyjafjallajökull, where an accurate plume height time series is available, modeled rates do agree better with Mobs than Mempir.