Finding the Missing Geomagnetic Dipole Signal in Global Pleointensity Data: Revisiting the High Southerly Latitudes

地磁场正在迅速减弱，导致一些人提出它将经历崩溃，然后恢复到通常的强度，但方向相反，这种现象被称为“极性反转”，发生在大约80万年前。这样的崩溃将对磁场保护我们免受宇宙射线轰击的能力产生潜在的破坏性影响，使我们的电网处于严重的危险之中。这种剧烈事件发生的概率取决于磁场的平均强度。如果平均值与现在的磁场大致相等（正如许多研究人员所假设的那样），那么磁场正在迅速下降的事实将比磁场比平均值高得多的事实更令人震惊，这是由南极古代磁场的当前数据所暗示的。关于平均场强的争论源于其估计的困难。这项提案中提倡的新方法将使研究人员能够获得南纬高纬度地区的可靠数据集，这将大大提高对古代平均磁场强度估计的信心，有助于我们评估地磁场灾难性崩溃的可能性。当我们研究古代磁场强度作为纬度函数的数据时，估计过去500万年的平均磁场强度的困难是显而易见的。地磁场的方向已经很好地近似于地球中心与自转轴对齐的轴向偶极子（棒状磁）。但是，这种轴向地磁偶极子的信号，即从赤道到两极的磁场强度加倍，在过去500万年的磁场强度估计数据库中并不明显。对于这一令人不安的失败，有几种可能的解释：1)将不同年龄的数据与可能不同的平均强度结合起来，导致对场强状态的不适当比较；2)高纬度地区场强下降，可能反映了“切线圆柱体”的作用？或者3)由于糟糕的选择标准或糟糕的实验设计而引入的噪声和/或偏差。后者是一种可能的解释，因为1960年夏威夷熔岩流的公布数据显示了今天在地球表面观测到的整个强度范围，但这次熔岩流的样本应该都有一个不同的值。这一建议得益于新的实验方法的发展，更好的现场策略和一种新的数据选择方法，这将允许通过全面的现场活动来准确估计古代磁场强度，从以前研究过的露头中收集熔岩流样本，目标是最有希望的物质。这些将使用最可靠的实验方案进行分析，并遵循严格的选择标准，这些标准已被证明可以拒绝不准确的结果，从而对古代场强进行准确和精确的估计。

The geomagnetic field is decreasing rapidly, leading some to propose that it will undergo collapse followed by a return to its usual strength but in the opposite direction, a phenomenon known as a "polarity reversal" which happened last approximately 800,000 years ago. Such a collapse would have a potentially devastating effect on the ability of the magnetic field to shield us from cosmic ray bombardment, placing our electrical grid at grave risk, among other things. The probability of such a drastic event happening depends on the average strength of the magnetic field. If the average is approximately equal to the present field (as many researchers assume), then the fact that the field is dropping rapidly would be more alarming than if the magnetic field is quite a bit higher than average, as implied by the current data for the ancient magnetic field from Antarctica. The argument over the average field strength stems from the difficulty of its estimation. The new approach advocated for in this proposal will allow researchers to obtain a robust data set for high southerly latitudes which will greatly enhance confidence in estimates of the average ancient field strength, contributing to our ability to assess the likelihood of catastrophic collapse of the geomagnetic field. The difficulty in estimating the average magnetic field strength over the past five million years is apparent when one examines data for ancient field strength as a function of latitude. Directions of the geomagnetic field have been well approximated by an axial dipole (bar magnetic) at the center of the Earth that is aligned with the spin axis. But the signal of such an axial geomagnetic dipole, whereby the field strength doubles from the equator to the poles, is not readily apparent in the database of field strength estimates from the last five million years. There are several possible explanations for this troubling failure: 1) combining data from different ages with possibly different average intensities leads to an inappropriate comparison of field states, 2) there is a depression of field strength at high latitude, perhaps reflecting the role of the `tangent cylinder?, or 3) there is noise and/or bias introduced by poor selection criteria or poor experimental design. The latter is a likely explanation as published data from the 1960 lava flow on Hawaii display the entire range of intensity values observed on the Earth's surface today, yet samples from this lava flow should all have one distinct value. This proposal benefits from the development of new experimental methods, better field strategies and a new approach to data selection that will allow accurate estimation of the ancient field strength through a comprehensive field campaign to collect lava flow samples from previously studied outcrops targeting the most promising material. These will be analyzed using the most robust experimental protocol and subjected to rigorous selection criteria proven to reject inaccurate results, leading to both accurate and precise estimates of ancient field strength.