SW_FAC_TMS_2F

Field-aligned currents (dual-satellite A-C)

Thematic areas: Ionosphere/Magnetosphere, Space Weather

Applicable missions: Swarm

Applicable spacecraft: Swarm-A, Swarm-C

Description

Time series of field-aligned and radial current densities along the orbit using the dual-satellite method. 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, except for latitudes θ>86° (near poles), where both FAC and IRC values are set to NaN.

Note that the magnetic field data used for the dual-satellite method is low-pass filtered with a 3-dB cutoff period of 20 s (corresponding to a wavelength of 150 km). This step is indispensable because the lateral distance between Swarm A and Swarm C has to be taken into account.

Data access

FAST processing

N/A

Preview image

(delivered separately)

File contents

Variable Units Description Dim Type
Timestamp ms Time, UTC 1 CDF_EPOCH
Latitude degrees Position in ITRF, Latitude 1 CDF_DOUBLE
Longitude degrees Position in ITRF, Longitude 1 CDF_DOUBLE
Radius m Position in ITRF, Radius 1 CDF_DOUBLE
IRC uA/m2 Ionospheric radial current (IRC) 1 CDF_DOUBLE
IRC_Error uA/m2 uncertainty of IRC 1 CDF_DOUBLE
FAC uA/m2 Field-aligned current (FAC) 1 CDF_DOUBLE
FAC_Error uA/m2 uncertainty of FAC 1 CDF_DOUBLE
Flags - 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

More details

Product identifier FAC_TMS_2F
Definition
Time series of field-aligned and radial current densities along the orbit using the dual-satellite method. 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, except for latitudes θ>86° (near poles), where both FAC and IRC values are set to NaN.
  
Note that the magnetic field data used for the dual-satellite method is low-pass filtered with a 3-dB cutoff period of 20 s (corresponding to a wavelength of 150 km). This step is indispensable because the lateral distance between Swarm A and Swarm C has to be taken into account.
Input data MAGA_LR_1B, MAGC_LR_1B, Time stamps (UTC), AUX_IGR_2F, AUX_COR_2F, AUX_LIT_2F, AUX_PMF_2F, AUX_F10_2F, AUX_DST_2F, AUX_IMF_2F, AUX_SWV_2F, AUX_PSM_2F, AUX_PGM_2F
Input time span 3 days
Spatial representation Current density estimates along entire orbits at positions between Swarm A and C
Time representation Time series of current density, Δt=1sec
Units Current density: µA/m2
Resolution Current density: 1E-6 µA/m2
Uncertainty 50 nA/m2 for periods 10s to 90min 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 5 MB per day
Output data CDF file with time series
Output time span 1day
Update rate 1 per day
Latency 10 min
Notes  

Flags: A table below presents the list of 10 individual and independent digits, characterizing the FAC-dual (FAC_TMS_2F) product quality. Digits from 1 to 8 report issues that may have been 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 mark the number of measurement points that were affected and value 0 marks not affected ones. For FAC-dual N can be equal to 1, 2, 3, or 4. Flags_B, Flags_F and Flags_q are handed through from Level 1b processing

Digit-Nr. Value Meaning
1 0/N A short (< 5 seconds) data gap occurred, which was interpolated linearly
2 0/N A long (> 5 seconds) data gap occurred, which cannot be interpolated linearly, in the vicinity
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 0/1 For FAC-dual, this digit is equal to 1 if latitude |θ| >86° (near geographic poles)
(IRC = NaN and FAC = NaN)
10 0/1 This digit is equal to 1 if inclination |I| < 30° (near magnetic equator)
(FAC = NaN)

Related resources

Swarm L2 FAC-dual Product Description

Changelog

N/A