Palaeomagnetic interpretation of dynamo simulations
Palaeomagnetic interpretation of dynamo simulations
复制标题
发电机模拟的古地磁解释
DOI：
10.1111/j.1365-246x.2005.02665.x
复制
发表时间：
2005
影响因子：
2.8
通讯作者：
Johannes Wicht
中科院分区：
文献类型：
--
作者：
Johannes Wicht
总结
地磁场漂移和反转的性质通常仅从一个古地磁场站点推断。然而，发电机模拟表明，相对偶极子的贡献是较低的过渡时期比在稳定时期。因此，局部场特性变得更加重要，并导致虚拟偶极子特征的局部差异增加。这些差异反过来解释了推断的偏移和反转属性的较大的站点依赖性。自洽的数值发电机模拟是用来测试和量化这种影响。反转持续时间的估计被发现不同的数量级取决于网站的位置。游览也是如此。此外，并非所有的短途旅行都是全球现象。在高纬度地区存在大量较小的漂移。这可以归因于在古地磁数据中也发现的长期变化的纬度增加。更大的偏移更有可能在全球范围内观察到，但特定的特征可能因地点而异。据推测，这些游览有一个不同的动力学起源从长期变化。
SUMMARY
The properties of geomagnetic field excursions and reversals are commonly inferred from one palaeomagnetic site only. However, dynamo simulations suggest that the relative dipole contribution is lower during transitional times than in stable periods. Local field properties thus become more important and cause increased local differences in virtual dipole signatures. These differences in turn account for a larger site dependence of inferred excursion and reversal properties. A self-consistent numerical dynamo simulation is used to test and quantify this effect. Estimates of reversal durations are found to vary by an order of magnitude depending on the site location. The same is true for excursions. Moreover, not all excursions are global phenomena. A larger number of smaller excursions are present at higher latitudes. This can be attributed to a latitudinal increase in secular variation that is also found in palaeomagnetic data. Larger excursions are more likely to be observed globally, but the particular signature may vary significantly from site to site. It is speculated that these excursions have a different dynamical origin from secular variation.