Comparative study of geomagnetic models with different spatio-temporal resolutions and measured data from geomagnetic stations
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摘要: 本研究首先在近年来磁场变化较快的北极以及南大西洋异常区选取了国际地磁台网(INTERMAGNET)的4个地磁台站,利用国际地磁参考场模型IGRF以及目前国内时空分辨率最高的多场源模型Swarm模型两个时空分辨率不同的全球地磁场模型,定量研究了模型空间分辨率以及更新周期对地磁台站实测值的影响。研究结果表明:(1)同等更新周期情况下,在太阳活动宁静时期,对于岩石圈磁异常不明显的区域,IGRF和其它空间分辨率更高的地磁场模型给出的结果较为接近,而对于岩石圈磁异常较为明显的区域,空间分辨率更高的全球地磁场模型更接近实测值;(2)在IGRF未更新的五年内,地磁台站实测值与IGRF模型之间存在明显的时间漂移,典型漂移可达100nT以上,但漂移的量值也存在地区差异,这与地磁场全球变化不均匀有关。而相比之下,地磁台站观测值与Swarm模型之间则未观测到明显的漂移。这一结果表明在地磁场快速变化时期,缩短主磁场的更新周期十分必要。INTERMAGNET全球120个台站统计结果也表明,在IGRF五年更新周期内,Swarm模型相较于IGRF模型与观测值结果残差的均值和绝对中位差都更小,更高时空分辨率的Swarm模型计算结果更接近观测值,描述地磁场的精确度更高。本项研究工作可以为全球地磁模型的相关应用提供依据和参考。Abstract: This study focuses on four INTERMAGNET geomagnetic stations located in the Arctic region and South Atlantic Anomaly regions, where rapid magnetic field changes have been observed in recent years. Utilizing two global geomagnetic field models with different spatial and temporal resolutions, the International Geomagnetic Reference Field (IGRF) model and the Swarm model, a multi-field source model that currently has the highest spatiotemporal resolution in the country, are used to quantitatively investigate the impact of model spatial resolution and updating period on the measured values at geomagnetic observatories. The findings indicate that: (1) For regions without distinct lithospheric magnetic anomalies, the results provided by IGRF and Swarm model are relatively close. However, for regions with more prominent lithospheric magnetic anomalies, the Swarm model with higher spatial resolution provides better agreement with the measurements. (2) In one IGRF updating cycle, there is a significant temporal drift between the geomagnetic station measurements and the IGRF model, with typical drifts up to 100 nT or more, but there were also regional variations in the magnitude of the drift, which was related to the heterogeneity of global variations in the geomagnetic field. In contrast, no significant drift was observed between the geomagnetic station observations and the Swarm model. These results suggest that it is necessary to shorten the updating period of the primary magnetic field during the period of rapid geomagnetic field changes. The statistical results from 120 INTERMAGNET stations around the world also show that, in the five-year update cycle of IGRF, the mean and absolute median differences between the residuals of the Swarm model and the observation results are smaller than those of the IGRF model, and the calculation results of the higher spatial and temporal resolution Swarm model are closer to the observations, which describes the geomagnetic field more accurately. This work can provide the basis and reference for the application of global geomagnetic model.
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Key words:
- Geomagnetic field model /
- Observatories measurement /
- IGRF /
- South Atlantic 43 Anomaly
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