Overview:
• Global magnetic field reference models
– WMM, IGRF & High Definition Geomagnetic Model
• Simple update of Williamson’s magnetic error values
– Breakdown by main, crustal and disturbance fields
– Adjustments for non-Gaussian error distribution
• Detailed error analysis
– Identify the primary factors contributing to the magnetic error Æ Accurate error model taking all relevant factors into account
Error tables for IGRF and HDGM
- Intention of this study:
- Provide error estimates for IGRF and HDGM corresponding to BGGM error tables (Macmillan, McKay and Grindrod, SPE/IADC 119851)
- Original plan: Reproduce BGGM tables for IGRF & HDGM
- New plan is to provide 2 options:
1.Simple: values to plug into the ISCWSA-2000 error model
2.Accurate: Breakdown by the primary error factors
- Methodology partly borrowed from Macmillan et al. study
- Simple error tables for IGRF and HDGM
• Compatible with the ISCWSA-2000 error model
• Breakdown by Main, Crustal and Disturbance field
• Percentiles accounting for non-Gaussian distribution
- Accurate error model accounting for further factors
• Main field: time since last model update (for IGRF!)
• Crustal field: degree of the model
• Disturbance field: Magnetic latitude and activity (Kp)
....
View the entire Presentation:
Quantifying the Uncertainty in Global Geomagnetic Models
Stefan Maus and Manoj Nair - NOAA/NGDC
Shola Okewunmi - Chevron