SW_FACxTMS_2F

Field-aligned currents (single satellite)

Authored by: GFZ Helmholtz Centre for Geosciences - https://ror.org/04z8jg394

Creation year: 2014

Product types: SW_OPER_FACATMS_2F, SW_OPER_FACBTMS_2F, SW_OPER_FACCTMS_2F

Thematic areas: Ionosphere/Magnetosphere, Space Weather

Applicable missions: Swarm

Applicable spacecraft: Swarm-A, Swarm-B, Swarm-C

Description

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.

Data access

FAST processing

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 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.
Input data MAGx_LR_1B, Satellite positions, 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 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:
  1. Binary to string: the byte is converted into a sequence of 0 and 1 characters.
  2. 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)

Related resources

Swarm L2 FAC-single Product Description

Changelog

N/A