Field coefficients for the CHAOS-1969 model in the .mat format

Field coefficients for the CHAOS-1969 model in the .mat format derived for the article "Localized origin at the core-mantle boundary of the 1969 geomagnetic impulse". Please refer to the project "Localized origin at the core-mantle boundary of the 1969 geomagnetic impulse" for further description (link in REFERENCES). Changes in version 2: - Uploaded README file - .mat file contains coefficients for all fieldsCHAOS-1969模型场系数的.mat格式文件，该文件为《1969年地磁脉冲核心-地幔边界局部起源》一文提供数据支持。请参阅项目《1969年地磁脉冲核心-地幔边界局部起源》以获取更详细的描述（参考文献中的链接）。版本2的更新如下：- 上传了README文件。- .mat文件包含所有场系数。