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This folder contains calibrated magnetic field data obtained from the AOCS magnetometer onboard the GRACE-FO satellites  and supporting data.
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The data is provided in NASA CDF format (https://cdf.gsfc.nasa.gov/).
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File name:

For example:
GF1_OPER_FGM_ACAL_CORR_20180601T000000_20180601T235959_0201.cdf

GF1:             GRACE-FO 1 (satellite identifier)
OPER:            operational (delivery mode)
FGM_ACAL_CORR:   Magnetic field data, aligned, calibrated and corrected (data category)
20180601T000000: yyyymmddThhhhhh (time of first entry)
20180601T235959: yyyymmddThhhhhh (time of last entry)
0201:            version 0201 (version identifier)
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Data categories

RAW:        Raw magnetic field data as provided by L1b
ACAL_CORR:  Magnetic field data, aligned, calibrated and corrected
CHAOS7:     CHAOS magnetic model predictions for core, crustal and large-scale magnetospheric field
APEX:       Magnetic coordinates (Emmert et al. (2010), https://doi.org/10.1029/2010JA015326)
FAC:        Radial and field-aligned currents derived from magnetic data in ACAL_CORR, erroneous from June 2020
FAC_v0202:  Radial and field-aligned currents derived from magnetic data in ACAL_CORR, completely recalculated due to error in FAC v0201
FAC_v0203:  Radial and field-aligned currents derived from magnetic data in ACAL_CORR and magnetic model in CHAOS7
PARAM_CAL:  Calibration parameters, monthly values
PARAM_CHAR: Charaterisation parameters, monthly values
ORBCNT:     Preliminary Orbit Counter created from TLE's, https://sscweb.gsfc.nasa.gov/cgi-bin/Locator.cgi
MISC:       Contains addional information, e.g. satellite velocity and geomagnetic indices
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References:

Michaelis, I., Stolle, C., Rother, M. (2021): GRACE-FO calibrated and characterized magnetometer data. V. 0201. GFZ Data Services. https://doi.org/10.5880/GFZ.2.3.2021.002

Stolle, C., Michaelis, I., Xiong, C. et al. Observing Earth’s magnetic environment with the GRACE-FO mission. Earth Planets Space 73, 51 (2021). https://doi.org/10.1186/s40623-021-01364-w
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License: CC BY 4.0
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Changes in processing wrt to reference

from Apr 2021 sklearn.linear_model.LinearRegression is using option (normalize=True)
For Dec 2024 has been reprocessed and version has been increased to v0202 (v0203 for FAC) for this month only. Reason was disagreement in the input data
from Dec 2024 CHAOS8 has been used as reference model and IGRF14 has been used for APEX
Added MISC folder containing addional information, e.g. satellite velocity and geomagnetic indices
For Feb 2025 has been reprocessed and version has been increased to v0202 (v0203 for FAC) for this month only. Reason was disagreement in the input data