1. The 3rd Swarm Science Meeting, 19-20 June 2014, Copenhagen, Denmark
The Swarm Level 2 Category-2 products: Field-Aligned Current, Ionospheric Bubble Index, and Total Electron Content
Jaeheung Park1, Jan Rauberg1, Patricia Ritter1, Max Noja2, Claudia Stolle1, and Hermann Lühr1
1Helmholtz Centre Potsdam, GFZ, German Research Centre for Geosciences, Telegrafenberg, Potsdam, Germany (contact:
2TomTom Telematics, Berlin, Germany
Field Aligned Current (FAC) / Ionospheric Radial Current (IRC)
[Ritter et al., 2013]
The FAC product gives field-aligned and radial current density estimated from single-satellite and/or dual-satellite observations of geomagnetic field vectors.
(1) The dual-satellite method
(2) The single-satellite method (a traditional method)
Ionospheric Bubble Index (IBI) [Park et al., 2013]
The IBI product consists of flags showing whether a magnetic field data point at a low latitude is disturbed by plasma irregularities or other artificial noise sources.
(1) The first processing step (high-pass filter applied to low-latitude magnetic field data)
(2) The second processing step (correlation between plasma density and magnetic field)
(3) Statistical distribution of bubbles identified by the Swarm IBI processor (prototype)
Swarm-A on 31-DEC-2013 (LT~23)
Plasma density (bubble)
L1b-MAG’
L1b-EFI
L2-IBI (prototype)
B-field perturbation
Flags: refer to (2) below 1 2 3 4
dℓ1
dℓ2
dℓ4
dℓ3
Swarm-A
Swarm-C
Swarm-C
Ampère's integral law
dt=5sec
 dl=38km
loop
Swarm-A NH SH
02 LT
14 LT
An event is considered as bubble
(Bubble flag = 1) when the anti-correlation is strong enough (e.g. R<-0.6)
High-pass filtered signals
Anti-correlation between b and ne
FACdual is low-pass filtered considering inter-satellite distance.
High occurrence rate near Brazil
High occurrence rate near Africa and the Pacific Ocean
Poor statistics because of :
(1) yet missing September equinox data
(2) Swarm orbits at post-midnight LT, where bubbles rarely occur (e.g., LT in March 2014)
strong FAC (~1 μA/m2)
High-latitude region
The amplitude and latitudinal distribution generally agree with those of previous studies:
overall FAC amplitudes reach ~1 μA/m2,
the FACs between 65o-80o MLAT are generally stronger than those at lower and higher latitudes.
Total Electron Content (TEC) [Noja et al., 2013]
The TEC product is composed of slant electron content integrated along the line of sight from Swarm to the GPS satellites. TEC values are estimated from GPS signal delay.
(1) Comparison between Swarm/STEC and Swarm/ne
The two profiles from the two independent Swarm instruments (GPS receiver and Langmuir probe) exhibit consistent latitude dependences.
(2) Ionospheric scale height estimated from the Swarm/STEC and Swarm/ne
Conclusions
This presentation showed results of first validation activities on three Swarm Level-2 Category-2 (CAT-2) data products: Field-Aligned Current (FAC), Ionospheric Bubble Index (IBI), and Total Electron Content (TEC):
The three Level-2 CAT-2 processors (FAC/IBI/TEC) work properly with real Swarm L1b data providing expected amplitude and variation.
These Level-2 CAT-2 products will be available at a public ftp-website (
Swarm/GPS
Swarm/GPS
Swarm/GPS
References
Ritter, P., H. Lühr, and J. Rauberg, Determining field-aligned currents with the Swarm constellation mission, Earth Planets Space, Vol. 65 (No. 11), pp , 2013.
Park, J., M. Noja, C. Stolle, and H. Lühr, The Ionospheric Bubble Index deduced from magnetic field and plasma observations onboard Swarm, Earth Planets Space, Vol. 65 (No. 11), pp , 2013.
Noja, M., C. Stolle, J. Park, and H. Lühr, Long-term analysis of ionospheric polar patches based on CHAMP TEC data, Radio Sci., 48, 289–301, doi: /rds.20033, 2013.
Alken, P., S. Maus, P. Vigneron, O. Sirol, and G. Hulot, Swarm SCARF equatorial electric field inversion chain, Earth Planets Space, Vol. 65 (No. 11), pp , 2013
Stolle, C. et al., Space Weather opportunities from the Swarm mission including near real time applications, Earth Planets Space, Vol. 65 (No. 11), pp , 2013
Olsen, N., et al., The Swarm Satellite Constellation Application and Research Facility (SCARF) and Swarm data products, Earth Planets Space, Vol. 65 (No. 11), pp ,
Swarm/LP
Swarm/LP
Swarm/LP
Swarm/GPS
(When the elevation angle is very high, STEC approximates to VTEC.)
The scale height of about 200 km has the order of magnitude consistent with those of previous studies.
The 3rd Swarm Science Meeting,
19-20 June 2014,
Copenhagen, Denmark
Swarm/LP