Geomagnetic Virtual Observatories

Description of GVO data product:
Geomagnetic Virtual Observatories (GVO) data are derived from satellite magnetic measurements. The GVO data products consists of magnetic field time series regularly distributed in space and time. GVO time series including all field contributions, and those processed to isolate the core field, are available along with estimated errors.

The GVO product are designed to make satellite data more accessible to researchers studying the physics of the core dynamo process, and related phenomenon such are secular variation, geomagnetic jerks and rapid core dynamics. In addition, the GVO product also provide valuable information to those interested in investigating magnetospheric and ionospheric magnetic signals on timescales of months and longer. 

GVO data products of 1, 4 and 12 month cadance are available for the Ørsted mission (1999-2005), the CHAMP mission (2000-2010), the CryoSat-2 mission (2010-2018), the Grace mission (2007-2018, 12 month only) and the Swarm mission (2014-2022). In addition, a composite GVO dataset derived from all the above missions (with the execption of Grace) are available covering 1999-2022.

The GVO data products are given as CDF files providing the magnetic field components, the secular variation field components, and their associated error estimates, all provided in a global grid of 300 Geomagnetic Virtual Observatories. For each satellite zip compressed folders contains the CDFs and a ReadMe.txt file which provides details on the datasets and how these where made. 

References:
Hammer, M.D, Finlay, C.C, and Olsen, N. (2021) Applications for CryoSat-2 satellite magnetic data in studies of the Earth's core field variations. Earth, Planets and Space, 73:73.

Hammer, M.D., Cox, G. A., Brown, W. J., Beggan, C. D., & Finlay, C. C. (2021). Geomagnetic Virtual Observatories: monitoring geomagnetic secular variation with the Swarm satellites. Earth, Planets and Space, 73(1), 1-22.

GVO数据产品描述：

地磁虚拟观测站（GVO）数据源自卫星磁场测量。GVO数据产品包括在时空上均匀分布的磁场时间序列。GVO时间序列涵盖了所有场贡献，以及经过处理以隔离地核场的序列，并附带估计误差。

GVO产品旨在使卫星数据更易于研究人员研究地核动力学过程物理学，以及与之相关的现象，例如长期变化、地磁突变和快速地核动力学。此外，GVO产品还为那些对在数月至更长时间尺度上研究磁层和电离层磁场信号感兴趣的研究者提供了宝贵的信息。

针对Ørsted任务（1999-2005年）、CHAMP任务（2000-2010年）、CryoSat-2任务（2010-2018年）、Grace任务（2007-2018年，仅12个月）以及Swarm任务（2014-2022年）的数据产品，1个月、4个月和12个月的观测频率均可用。此外，由上述任务（除Grace任务外）生成的综合GVO数据集覆盖了1999-2022年。

GVO数据产品以CDF文件形式提供，包含磁场分量、长期变化场分量及其相关的误差估计，这些数据均以全球300个地磁虚拟观测站的全局网格形式提供。每个卫星的压缩文件夹中包含CDF文件以及ReadMe.txt文件，后者提供了数据集的详细信息以及数据是如何生成的。

参考文献：

Hammer, M.D, Finlay, C.C, and Olsen, N. (2021) CryoSat-2卫星磁场数据在研究地球地核场变化中的应用。地球、行星与空间，73：73。

Hammer, M.D., Cox, G. A., Brown, W. J., Beggan, C. D., & Finlay, C. C. (2021). 地磁虚拟观测站：利用Swarm卫星监测地磁长期变化。地球、行星与空间，73(1)，1-22。