Short product names


Full product name
Auroral oval boundaries derived from FACs


This product contains the auroral oval boundaries, associated with auroral precipitation, estimated from the presence of small-scale (<150 km) field-aligned currents.

Output variables

t Time of observation, UTC1CDF_EPOCH
LatitudedegPosition in ITRF - Geocentric latitude1CDF_DOUBLE
LongitudedegPosition in ITRF - Geocentric longitude1CDF_DOUBLE
RadiusmPosition in ITRF - Geocentric radius (from the Earth center)1CDF_DOUBLE
Latitude_QDdegQuasi-dipole latitude1CDF_DOUBLE
Longitude_QDdegQuasi-dipole longitude1CDF_DOUBLE
MLThourMagnetic Local Time (QD)1CDF_DOUBLE
Boundary_FlagIndicator for equatorward (=1) or poleward (=2) boundary1CDF_UINT1
QualityQuality indicator of equatorward/poleward boundary (Pa, Sigma)2CDF_DOUBLE
Pair_IndicatorIndicator of equatorward/poleward boundary of auroral oval. If the auroral oval boundaries are detectable as one pair, the pair indicator represents the record of previous (-1) or next (1) equatorward/poleward boundary within one pair; otherwise, the pair indicator is set to 01CDF_INT1


Product Identifier AOBxFAC_2F
Definition Auroral Oval Boundaries using the FAC method
Input Data FACxTMS_2F1
Input Time Span Up to one year
Spatial representation One geographic and quasi-dipole latitude/longitude as well as magnetic local time for each output value at the nearest magnetic-field measurement.
Time representation One timestamp for each boundary represented by the geographic and quasi-dipole latitude/longitude as well as magnetic local time.
Units Degrees
Resolution Full resolution (Double precision)
Uncertainty 3 deg, c.f. Xiong, C. and Lühr, H., doi: 10.5194/angeo-32-623-2014
Quality indicator
Value Meaning
Pa Slop of linear fit of S value. Users are suggested to use boundaries with pa larger than 0.2
Sigma The standard deviation of the linear fit of S value. Users are suggested to use boundaries with σ less than 0.4. See SW-DS-GFZ-GS-001_AEBS_DPA Swarm-AEBS Description of the Processing Algorithm, for the S value definition
Data volume Up to 2.5 MB
Data format CDF
Output time span Up to one year2
Update rate Daily
Latency < 1 day
Notes 1 Version information of Input Data are available in the CDF global attributes.
2 Product always contain data from the start of the first oval crossing of the year until the end of the last oval crossing starting that year, i.e., may contain data from the next year if oval crossing occurs around midnight.