Time series of field-aligned and radial current densities along the orbit from single satellite measurements. Field-aligned current (FAC) density is derived by the multiplication of the radial current (IRC) density with the inclination angle of the geomagnetic field. The field-aligned current density can only be calculated at latitudes, where the magnetic field is well inclined, i.e. |I| > 30°. Near the magnetic equator for magnetic inclination angles |I| < 30° FAC values are set to NaN. The radial current density can be provided along the whole orbit. Scale size >7.5 km.
Flags characterizing the product quality (processing flags)
1
CDF_UINT4
Flags_F
-
Flags_F passed through from L1b and accumulated for quad points
1
CDF_UINT4
Flags_B
-
Flags_B passed through from L1b and accumulated for quad points
1
CDF_UINT4
Flags_q
-
Flags_q passed through from L1b and accumulated for quad points
1
CDF_UINT4
Details
Product identifier
FACxTMS_2F
Definition
Time series of field-aligned and radial current densities along the orbit from single satellite measurements. Field-aligned current (FAC) density is derived by the multiplication of the radial current (IRC) density with the inclination angle of the geomagnetic field. The field-aligned current density can only be calculated at latitudes, where the magnetic field is well inclined, i.e. |I| > 30°. Near the magnetic equator for magnetic inclination angles |I| < 30° FAC values are set to NaN. The radial current density can be provided along the whole orbit. Scale size >7.5 km.
Current density estimates along entire orbits at positions of Swarm A, B, and C.
Time representation
Time series of current density, Δt=1sec
Units
Current density: µA/m2
Resolution
Current density: 1E-6 µA/m2
Uncertainty
less than FAC_TMS_2F, 70 nA/m2 on top of constant bias of <200nA/m2, for latitudes below 80°, gradually degrading between 80° to 86°, no values beyond 86°
Quality indicator
See Flags
Data volume
5MB per day, per satellite
Output data
CDF file with time series
Output time span
1day
Latency
10 min
Update rate
1 per day
Notes
Flags: The table below presents a list of 10 individual and independent digits characterising the FAC-single (FACxTMS_2F) product quality. Digits from 1 to 8 report issues that may have occurred at one or more of the measurement points used for the computation of a current density value. Digits 9 and 10 report whether the NaN values for the current density were used or not. Values N > 0 indicate how many measurement points were affected, while N = 0 indicates that none were affected. In single-satellite FAC processing, affected values (N > 0) can only be 1 or 2.
Flags_B, Flags_F, and Flags_q are passed from Level-1b processing and stored in an n × 3 matrix. During data import, each binary flag byte is converted into an integer in two steps:
Binary to string: the byte is converted into a sequence of 0 and 1 characters.
String to number: this bit string is then converted into a floating-point value whose integer part represents the encoded bit pattern.
For each current estimate, the flag values from all contributing measurement points are summed, following the same approach described above. Here, up to two points contribute, so each digit of the combined flag can range from 0 to 2. The default value is 0, and the resulting accumulated flag reflects the overall status of all measurement points associated with that current position.
Digit-Nr.
Value
Meaning
1
0/N
A short (< 5 seconds) data gap occurred, which was interpolated linearly
2
0
For FAC-single, this digit is always zero because no filtering is done
3
0/N
No EST (external part of AUX_DST_2F) data were available, and a default value was used for the magnetospheric field model
4
0/N
No IST (external part of AUX_DST_2F) data were available, and a default value was used for the magnetospheric field model
5
0/N
No solar radio flux (AUX_F10_2F) data were available, and a default value was used for the magnetospheric field model
6
0/N
No interplanetary magnetic field (AUX_IMF_2F) data were available, and a default value was used for the magnetospheric field model
7
0/N
No Em (merging electric field) data were available, and a default value was used for the magnetospheric field model
8
0/N
No magnetospheric field coefficients (Aux_PMF_2F or Aux_PSM_2F or Aux_PGM_2F) were available, and magnetospheric field is set to 0
9
0
For FAC-single, this digit is always equal to 0
10
0/1
This digit is equal to 1 if inclination |I| < 30° (near magnetic equator)
(FAC = NaN)
