VirES for Swarm — HAPI Server

The Heliophysics Application Programming Interface (HAPI) is a community specification of a unified interface for accessing data time-series. The VirES for Swarm acts as a HAPI server and allows access to selected datasets via the HAPI interface.

For more details about see the HAPI Specification.

HAPI clients for various programming environments can be found here.

Terms and Conditions

The access and use of Swarm products are regulated by ESA's Data Policy and subject to the acceptance of the specific Terms and Conditions.

The VirES for Swarm HAPI end-point, unlike the other VirES APIs, does not require user authentication. The datasets published via the VirES for Swarm HAPI interface are accessible freely.

Available Datasets

This section list available datasets grouped by the type and their parameters (click to expand the collapsed lists). Click a dataset name to see its HAPI JSON info response.

dataset description
SW_FAST_MODA_SC_1B Swarm A S/C fast track position from the preliminary Medium Accuracy Orbit Determination (MOD). The original SP3c records have been converted to UTC and ITRF spherical coordinates.
SW_FAST_MODB_SC_1B Swarm B S/C fast track position from the preliminary Medium Accuracy Orbit Determination (MOD). The original SP3c records have been converted to UTC and ITRF spherical coordinates.
SW_FAST_MODC_SC_1B Swarm C S/C fast track position from the preliminary Medium Accuracy Orbit Determination (MOD). The original SP3c records have been converted to UTC and ITRF spherical coordinates.
SW_OPER_MODA_SC_1B Swarm A S/C position from the preliminary Medium Accuracy Orbit Determination (MOD). The original SP3c records have been converted to UTC and ITRF spherical coordinates.
SW_OPER_MODB_SC_1B Swarm B S/C position from the preliminary Medium Accuracy Orbit Determination (MOD). The original SP3c records have been converted to UTC and ITRF spherical coordinates.
SW_OPER_MODC_SC_1B Swarm C S/C position from the preliminary Medium Accuracy Orbit Determination (MOD). The original SP3c records have been converted to UTC and ITRF spherical coordinates.
parameter / type description
Timestamp
isotime
Time stamp
Latitude
double
Position in ITRF - Latitude
Longitude
double
Position in ITRF - Longitude
Radius
double
Position in ITRF - Radius
dataset description
SW_FAST_MAGA_LR_1B Swarm A vector (VFM) and scalar (ASM) magnetic field fast track measurements interpolated at 1Hz rate.
SW_FAST_MAGB_LR_1B Swarm B vector (VFM) and scalar (ASM) magnetic field fast track measurements interpolated at 1Hz rate.
SW_FAST_MAGC_LR_1B Swarm C vector (VFM) and scalar (ASM) magnetic field fast track measurements interpolated at 1Hz rate.
SW_OPER_MAGA_LR_1B Swarm A vector (VFM) and scalar (ASM) magnetic field measurements interpolated at 1Hz rate.
SW_OPER_MAGB_LR_1B Swarm B vector (VFM) and scalar (ASM) magnetic field measurements interpolated at 1Hz rate.
SW_OPER_MAGC_LR_1B Swarm C vector (VFM) and scalar (ASM) magnetic field measurements interpolated at 1Hz rate.
parameter / type description
Timestamp
isotime
Time stamp
Latitude
double
Position in ITRF - Latitude
Longitude
double
Position in ITRF - Longitude
Radius
double
Position in ITRF - Radius
F
double
Magnetic field intensity
dF_Sun
double
Magnetic stray field correction intensity of Sun ASM frame
dF_AOCS
double
Magnetic stray field correction intensity of AOCS magneto-torquer coils
dF_other
double
Magnetic stray field correction intensity of all other sources
F_error
double
Error estimate on magnetic field intensity
B_VFM[3]
double
Magnetic field vector, VFM frame
B_NEC[3]
double
Magnetic field vector, NEC frame
dB_Sun[3]
double
Magnetic stray field correction vector of Sun induced perturbation, VFM frame
dB_AOCS[3]
double
Magnetic stray field correction vector of AOCS magneto-torquer coils, VFM frame
dB_other[3]
double
Magnetic stray field correction vector of all other sources, VFM frame
B_error[3]
double
Error estimates on magnetic field, VFM frame
q_NEC_CRF[4]
double
Quaternion, transformation: NEC ← CRF
Att_error
double
Error estimates on attitude information
Flags_F
integer
Flags characterizing the magnetic field intensity measurement (F)
Flags_B
integer
Flags characterizing the magnetic field measurement
Flags_q
integer
Flags characterizing the attitude information
Flags_Platform
integer
Flags characterizing the S/C platform information
ASM_Freq_Dev
double
ASM frequency calibration data deviation
SyncStatus
integer
Synchronization status
B_NEC_Model[3]
double
CHAOS magnetic model
F_Model
double
CHAOS magnetic model, field intensity
F_res_Model
double
Magnetic field intensity, CHAOS magnetic model residual
B_NEC_res_Model[3]
double
Magnetic field vector, NEC frame, CHAOS magnetic model residual
dataset description
SW_FAST_MAGA_HR_1B Swarm A vector (VFM) magnetic field fast track measurements at 50Hz rate.
SW_FAST_MAGB_HR_1B Swarm B vector (VFM) magnetic field fast track measurements at 50Hz rate.
SW_FAST_MAGC_HR_1B Swarm C vector (VFM) magnetic field fast track measurements at 50Hz rate.
SW_OPER_MAGA_HR_1B Swarm A vector (VFM) magnetic field measurements at 50Hz rate.
SW_OPER_MAGB_HR_1B Swarm B vector (VFM) magnetic field measurements at 50Hz rate.
SW_OPER_MAGC_HR_1B Swarm C vector (VFM) magnetic field measurements at 50Hz rate.
parameter / type description
Timestamp
isotime
Time stamp
Latitude
double
Position in ITRF – Latitude
Longitude
double
Position in ITRF – Longitude
Radius
double
Position in ITRF – Radius
B_VFM[3]
double
Magnetic field vector, VFM frame
B_NEC[3]
double
Magnetic field vector, NEC frame
dB_Sun[3]
double
Magnetic stray field correction vector of Sun induced perturbation, VFM frame
dB_AOCS[3]
double
Magnetic stray field correction vector of AOCS magneto-torquer coils, VFM frame
dB_other[3]
double
Magnetic stray field correction vector of all other sources, VFM frame
B_error[3]
double
Error estimates on magnetic field, VFM frame
q_NEC_CRF[4]
double
Quaternion, transformation: NEC ← CRF
Att_error
double
Error estimates on attitude information
Flags_B
integer
Flags characterizing the magnetic field measurement
Flags_q
integer
Flags characterizing the attitude information
Flags_Platform
integer
Flags characterizing the S/C platform information
SyncStatus
integer
Synchronization status
dataset description
CS_OPER_MAG Cryosat-2 Platform magnetometer measurements
parameter / type description
Timestamp
isotime
Time stamp
Latitude
double
Position in ITRF - Latitude
Longitude
double
Position in ITRF - Longitude
Radius
double
Position in ITRF - Radius
B_FGM1[3]
double
calibrated magnetic vector from FGM1, in instrument frame
B_FGM2[3]
double
calibrated magnetic vector from FGM2, in instrument frame
B_FGM3[3]
double
calibrated magnetic vector from FGM3, in instrument frame
B_NEC1[3]
double
calibrated and aligned magnetic vector from FGM1, in NEC (North, East, Center) frame
B_NEC2[3]
double
calibrated and aligned magnetic vector from FGM2, in NEC (North, East, Center) frame
B_NEC3[3]
double
calibrated and aligned magnetic vector from FGM3, in NEC (North, East, Center) frame
B_NEC[3]
double
calibrated and aligned magnetic vector in NEC (North, East, Center) frame, 5 sample (i.e. 20 second) robust average of all 3 FGM
F
double
magnetic field intensity determined from B_NEC
B_mod_NEC[3]
double
CHAOS-6 model field (core, crust + magnetosphere), in NEC (North, East, Center) frame
q_NEC_CRF[4]
double
Quaternion, transformation: NEC <- CRF
q_error
double
experimental error indicator of attitude given in Quaternion q_NEC_CRF. Bad attitude if > approx 40
B_NEC_Model[3]
double
CHAOS magnetic model
F_Model
double
CHAOS magnetic model, field intensity
F_res_Model
double
magnetic field intensity determined from B_NEC, CHAOS magnetic model residual
B_NEC_res_Model[3]
double
calibrated and aligned magnetic vector in NEC (North, East, Center) frame, 5 sample (i.e. 20 second) robust average of all 3 FGM, CHAOS magnetic model residual
B_NEC1_res_Model[3]
double
calibrated and aligned magnetic vector from FGM1, in NEC (North, East, Center) frame, CHAOS magnetic model residual
B_NEC2_res_Model[3]
double
calibrated and aligned magnetic vector from FGM2, in NEC (North, East, Center) frame, CHAOS magnetic model residual
B_NEC3_res_Model[3]
double
calibrated and aligned magnetic vector from FGM3, in NEC (North, East, Center) frame, CHAOS magnetic model residual
dataset description
GRACE_A_MAG GRACE 1 platform magnetometer measurements
GRACE_B_MAG GRACE 2 platform magnetometer measurements
parameter / type description
Timestamp
isotime
Time stamp
Latitude
double
Position in ITRF - Latitude
Longitude
double
Position in ITRF - Longitude
Radius
double
Position in ITRF - Radius
B_FGM[3]
double
calibrated magnetic vector from FGM, in instrument frame
B_NEC_raw[3]
double
calibrated and aligned magnetic vector in NEC (North, East, Center) frame
B_NEC[3]
double
calibrated and aligned magnetic vector in NEC (North, East, Center) frame, 11 sample (i.e. 11 second) robust average
F
double
magnetic field intensity determined from B_NEC
q_NEC_CRF[4]
double
Quaternion, transformation: NEC <- CRF
q_error
double
experimental error indicator of attitude given in Quaternion q_NEC_CRF. Bad attitude if > approx 40
B_NEC_Model[3]
double
CHAOS magnetic model
F_Model
double
CHAOS magnetic model, field intensity
F_res_Model
double
magnetic field intensity determined from B_NEC, CHAOS magnetic model residual
B_NEC_res_Model[3]
double
calibrated and aligned magnetic vector in NEC (North, East, Center) frame, 11 sample (i.e. 11 second) robust average, CHAOS magnetic model residual
dataset description
GF1_OPER_FGM_ACAL_CORR GRACE-FO 1 platform magnetometer measurements
GF2_OPER_FGM_ACAL_CORR GRACE-FO 2 platform magnetometer measurements
parameter / type description
Timestamp
isotime
Time stamp
Latitude
double
Position in ITRF - Latitude
Longitude
double
Position in ITRF - Longitude
Radius
double
Position in ITRF - Radius
B_FGM[3]
double
Fluxgate magnetometer, FGM, aligned, vector-vector calibrated and corrected for satellite disturbances, FGM frame
B_NEC[3]
double
Fluxgate magnetometer, FGM, aligned, vector-vector calibrated and corrected for satellite disturbances, NEC frame
q_NEC_FGM[4]
double
Quaternion, transformation: NEC ... FGM
dB_MTQ_FGM[3]
double
Disturbance field related to magnetorquer, FGM frame
dB_XI_FGM[3]
double
Disturbance field related to 2nd order non-linearities, FGM frame
dB_NY_FGM[3]
double
Disturbance field related to 3rd order non-linearities, FGM frame
dB_BT_FGM[3]
double
Disturbance field related to temperature dependency of offsets, FGM frame
dB_ST_FGM[3]
double
Disturbance field related to temperature dependency of scale factors, FGM frame
dB_SA_FGM[3]
double
Disturbance field related to solar array currents, FGM frame
dB_BAT_FGM[3]
double
Disturbance field related to battery currents, FGM frame
B_FLAG
integer
Flags
B_NEC_Model[3]
double
CHAOS magnetic model
B_NEC_res_Model[3]
double
Fluxgate magnetometer, FGM, aligned, vector-vector calibrated and corrected for satellite disturbances, NEC frame, CHAOS magnetic model residual
dataset description
GO_MAG_ACAL_CORR GOCE platform magnetometer measurements
parameter / type description
Timestamp
isotime
Time stamp
Latitude
double
Position in ITRF - Latitude
Longitude
double
Position in ITRF - Longitude
Radius
double
Position in ITRF - Radius
B_MAG[3]
double
Fluxgate magnetometer, combined MAG, aligned, vector-vector calibrated and corrected for satellite disturbances, SC frame
B_NEC[3]
double
Fluxgate magnetometer, combined MAG, aligned, vector-vector calibrated and corrected for satellite disturbances, NEC frame
q_SC_NEC[4]
double
Quaternion, transformation: SC ... NEC
q_MAG_SC[4]
double
Quaternion, transformation: MAG ... SC
dB_MTQ_SC[3]
double
Disturbance field related to magnetorquer, SC frame
dB_XI_SC[3]
double
Disturbance field related to 2nd order non-linearities, SC frame
dB_NY_SC[3]
double
Disturbance field related to 3rd order non-linearities, SC frame
dB_BT_SC[3]
double
Disturbance field related to temperature dependency of offsets, SC frame
dB_ST_SC[3]
double
Disturbance field related to temperature dependency of scale factors, SC frame
dB_SA_SC[3]
double
Disturbance field related to solar array currents, SC frame
dB_BAT_SC[3]
double
Disturbance field related to battery currents, SC frame
dB_HK_SC[3]
double
Disturbance field related to housekeeping data, SC frame
dB_BLOCK_CORR[6]
double
Block correction for MAG2 and MAG3, MAG frame
B_FLAG
integer
Flags
B_NEC_Model[3]
double
CHAOS magnetic model
B_NEC_res_Model[3]
double
Fluxgate magnetometer, combined MAG, aligned, vector-vector calibrated and corrected for satellite disturbances, NEC frame, CHAOS magnetic model residual
dataset description
GO_MAG_ACAL_CORR_ML GOCE platform magnetometer measurements (ML calibrated)
parameter / type description
Timestamp
isotime
Time stamp
B_MAG[3]
double
Fluxgate magnetometer, combined MAG, aligned, vector-vector calibrated and corrected for satellite disturbances, SC frame
B_NEC[3]
double
Fluxgate magnetometer, combined MAG, aligned, vector-vector calibrated and corrected for satellite disturbances, NEC frame
B_FLAG
integer
Flag for combined FGM (Bit field:0: Data correct,1: Outlier detected,2: FGM interpolation corrupted)
Radius
double
Position in ITRF - Radius
Latitude
double
Position in ITRF - Latitude
NaN_FLAG
integer
Flag for filled NaN values with column mean value (0: Data complete,1: NaN values filled
Longitude
double
Position in ITRF - Longitude
q_FGM_NEC[4]
double
Quaternion, transformation: combined FGM ... NEC
MAGNETIC_ACTIVITY_FLAG
integer
Flag for filtered values using Hp30 and Dst indices (0: Geomagnetic quiet,1: Geomagnetic active: Hp30 > 2 or |Dst| > 30)
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
B_NEC_Model[3]
double
CHAOS magnetic model
B_NEC_res_Model[3]
double
Fluxgate magnetometer, combined MAG, aligned, vector-vector calibrated and corrected for satellite disturbances, NEC frame, CHAOS magnetic model residual
dataset description
SW_FAST_EFIA_LP_1B Swarm A plasma fast track data from the Langmuir Probe (LP) at 2Hz rate
SW_FAST_EFIB_LP_1B Swarm B plasma fast track data from the Langmuir Probe (LP) at 2Hz rate
SW_FAST_EFIC_LP_1B Swarm C plasma fast track data from the Langmuir Probe (LP) at 2Hz rate
SW_OPER_EFIA_LP_1B Swarm A plasma data from the Langmuir Probe (LP) at 2Hz rate
SW_OPER_EFIB_LP_1B Swarm B plasma data from the Langmuir Probe (LP) at 2Hz rate
SW_OPER_EFIC_LP_1B Swarm C plasma data from the Langmuir Probe (LP) at 2Hz rate
parameter / type description
Timestamp
isotime
Time stamp
Latitude
double
Position in ITRF – Latitude
Longitude
double
Position in ITRF – Longitude
Radius
double
Position in ITRF – Radius
U_orbit
double
Spacecraft velocity in the ITRF
Ne
double
Plasma density (electron)
Ne_error
double
Error estimate of plasma density (Ne)
Te
double
Plasma electron temperature
Te_error
double
Error estimate of plasma electron temperature (Te)
Vs
double
Spacecraft potential
Vs_error
double
Error estimate of spacecraft potential (U_pol)
Flags_LP
integer
Flags indicating the source/method of LP measurements (ne, Te, Vs)
Flags_Ne
integer
Flags characterizing the plasma density measurement
Flags_Te
integer
Flags characterizing the electron temperature measurement
Flags_Vs
integer
Flags characterizing the spacecraft potential measurement
SyncStatus
integer
Synchronization status
dataset description
SW_PREL_EFIAIDM_2_ Swarm A LP ion drift, density and effective mass data
SW_PREL_EFIBIDM_2_ Swarm B LP ion drift, density and effective mass data
SW_PREL_EFICIDM_2_ Swarm C LP ion drift, density and effective mass data
parameter / type description
Timestamp
isotime
Time of observation
Latitude_GD
double
WGS84 geodetic latitude
Longitude_GD
double
WGS84 geodetic longitude
Height_GD
double
Height above WGS84 reference ellipsoid
Radius_GC
double
Geocentric radius
Latitude_QD
double
Quasi-dipole latitude
MLT_QD
double
Magnetic local time
V_sat_nec[3]
double
Satellite velocity in north, east, centre (NEC) reference frame.
M_i_eff
double
Ion effective mass.
M_i_eff_err
double
Ion effective mass uncertainty.
M_i_eff_Flags
integer
Ion effective mass validity flag.
M_i_eff_tbt_model
double
Ion effective mass from Truhlik et al. (2015) topside empirical model.
V_i
double
Ion along-track drift.
V_i_err
double
Ion along-track drift uncertainty.
V_i_Flags
integer
Ion along-track drift validity flag.
V_i_raw
double
Ion along-track drift without high-latitude detrending.
N_i
double
Ion density.
N_i_err
double
Ion density unertainty.
N_i_Flags
integer
Ion density validity flag.
A_fp
double
Modified-OML EFI faceplate area.
R_p
double
Modified-OML Langmuir spherical probe radius.
T_e
double
Electron temperature.
Phi_sc
double
Spacecraft floating potential with respect to plasma potential far from satellite.
dataset description
SW_OPER_EFIATIE_2_ Swarm A Thermal Ion Imager (TII) ion temperatures estimate
SW_OPER_EFIBTIE_2_ Swarm B Thermal Ion Imager (TII) ion temperatures estimate
SW_OPER_EFICTIE_2_ Swarm C Thermal Ion Imager (TII) ion temperatures estimate
parameter / type description
Timestamp
isotime
Time of observation
Latitude_GD
double
WGS84 geodetic latitude
Longitude_GD
double
WGS84 geodetic longitude
Height_GD
double
Height above WGS84 reference ellipsoid
Radius_GC
double
Geocentric radius
Latitude_QD
double
Quasi-dipole latitude
MLT_QD
double
Magnetic local time
Tn_msis
double
Neutral temperature from NRLMSISE00 model
Te_adj_LP
double
Corrected Swarm LP electron temperature
Ti_meas_drift
double
Ion temperature estimated using Swarm TII drift at high latitudes
Ti_model_drift
double
Ion temperature estimated using Weimer 2005 model drifts at high latitude
Flag_ti_meas
integer
Flags characterising TII-based Ti: Bit0 = 1/0: high-latitude frictional heating included/omitted, Bit1=1/0: electron temperature from low/high-gain probe, Bit2=1/0: ion temperature data available/data value is set to NaN
Flag_ti_model
integer
Flags characterising model-based Ti: Bit0 = 1/0: high-latitude frictional heating included/omitted, Bit1=1/0: electron temperature from low/high-gain probe, Bit2=1/0: ion temperature data available/data value is set to NaN
dataset description
SW_EXPT_EFIA_TCT02 Swarm A Thermal Ion Imager (TII) cross track flow at 2Hz
SW_EXPT_EFIA_TCT16 Swarm A Thermal Ion Imager (TII) cross track flow at 16Hz
SW_EXPT_EFIB_TCT02 Swarm B Thermal Ion Imager (TII) cross track flow at 2Hz
SW_EXPT_EFIB_TCT16 Swarm B Thermal Ion Imager (TII) cross track flow at 16Hz
SW_EXPT_EFIC_TCT02 Swarm C Thermal Ion Imager (TII) cross track flow at 2Hz
SW_EXPT_EFIC_TCT16 Swarm C Thermal Ion Imager (TII) cross track flow at 16Hz
parameter / type description
Timestamp
isotime
Time stamp
Latitude
double
Position in ITRF – Latitude
Longitude
double
Position in ITRF – Longitude
Radius
double
Position in ITRF – Radius
Latitude_QD
double
Quasi-dipole latitude
MLT_QD
double
Magnetic local time
Vixh
double
Along-track ion drift from horizontal TII sensor in satellite-track coordinates.
Vixh_error
double
Random error estimate for along-track ion drift from horizontal TII sensor in satellite-track coordinates. Negative value indicates no estimate available.
Vixv
double
Along-track ion drift from vertical TII sensor in satellite-track coordinates.
Vixv_error
double
Random error estimate for along-track ion drift from vertical TII sensor in satellite-track coordinates. Negative value indicates no estimate available.
Viy
double
Cross-track horizontal ion drift from horizontal TII sensor in satellite-track coordinates.
Viy_error
double
Random error estimate for cross-track horizontal ion drift from horizontal TII sensor in satellite-track coordinates. Negative value indicates no estimate available.
Viz
double
Cross-track vertical ion drift from vertical TII sensor in satellite-track coordinates.
Viz_error
double
Random error estimate for cross-track vertical ion drift from vertical TII sensor in satellite-track coordinates. Negative value indicates no estimate available.
VsatN
double
Satellite velocity N component in north-east-centre coordinates.
VsatE
double
Satellite velocity E component in north-east-centre coordinates.
VsatC
double
Satellite velocity C component in north-east-centre coordinates.
Ehx
double
Electric field x component in satellite-track coordinates, derived from -VxB with along-track ion drift from horizontal sensor.
Ehy
double
Electric field y component in satellite-track coordinates, derived from -VxB with along-track ion drift from horizontal sensor.
Ehz
double
Electric field z component in satellite-track coordinates, derived from -VxB with along-track ion drift from horizontal sensor.
Evx
double
Electric field x component in satellite-track coordinates, derived from -VxB with along-track ion drift from vertical sensor.
Evy
double
Electric field y component in satellite-track coordinates, derived from -VxB with along-track ion drift from vertical sensor.
Evz
double
Electric field z component in satellite-track coordinates, derived from -VxB with along-track ion drift from vertical sensor.
Bx
double
Geomagnetic field x component in satellite-track coordinates, derived from the 1 Hz product.
By
double
Geomagnetic field y component in satellite-track coordinates, derived from the 1 Hz product.
Bz
double
Geomagnetic field z component in satellite-track coordinates, derived from the 1 Hz product.
Vicrx
double
Ion drift corotation signal x component in satellite-track coordinates. This has been removed from ion drift and electric field.
Vicry
double
Ion drift corotation signal y component in satellite-track coordinates. This has been removed from ion drift and electric field.
Vicrz
double
Ion drift corotation signal z component in satellite-track coordinates. This has been removed from ion drift and electric field.
Quality_flags
integer
Bitwise flag for each velocity component, where a value of 1 for a particular component signifies that calibration was successful, and that the baseline 1-sigma noise level is less than or equal to 100 m/s at 2 Hz. Electric field quality can be assessed from these flags according to -vxB. Bit0 (least significant) = Vixh, bit1 = Vixv, bit2 = Viy, bit3 = Viz. Refer to the release notes for details.
Calibration_flags
integer
Information about the calibration process. Refer to the release notes for details.
dataset description
SW_OPER_EEFATMS_2F Swarm A dayside equatorial electric field
SW_OPER_EEFBTMS_2F Swarm B dayside equatorial electric field
SW_OPER_EEFCTMS_2F Swarm C dayside equatorial electric field
parameter / type description
Timestamp
isotime
Time of satellite crossing of the magnetic equator, UTC
Longitude
double
Geographic longitude of satellite crossing of the magnetic equator
Latitude
double
Geographic latitude of satellite crossing of the magnetic equator
EEF
double
Estimate of the equatorial electric field
EEJ[81]
double
Height-integrated east current profile in QD latitude, spanning [-20:0.5:20] degrees
RelErr
double
Quality indicator of EEF estimate; relative error between modeled and observed current profile
Flags
integer
Flags describing data gaps and satellite identification
dataset description
SW_OPER_IBIATMS_2F Swarm A ionospheric bubble index
SW_OPER_IBIBTMS_2F Swarm B ionospheric bubble index
SW_OPER_IBICTMS_2F Swarm C ionospheric bubble index
parameter / type description
Timestamp
isotime
Time stamp in UTC
Latitude
double
Geographic latitude
Longitude
double
Geographic longitude
Radius
double
Geographic radius
Bubble_Index
integer
Plasma Bubble Index
Bubble_Probability
double
Detection probability of the plasma bubble
Flags_Bubble
integer
Flags related to the plasma bubble index
Flags_F
integer
Flags_F passed through from MAGx_L1_B
Flags_B
integer
Flags_B passed through from MAGx_L1_B
Flags_q
integer
Flags_q passed through from MAGx_L1_B
dataset description
SW_OPER_FACATMS_2F Swarm A field-aligned and radial current densities using the single satellite measurements
SW_OPER_FACBTMS_2F Swarm B field-aligned and radial current densities using the single satellite measurements
SW_OPER_FACCTMS_2F Swarm C field-aligned and radial current densities using the single satellite measurements
SW_OPER_FAC_TMS_2F Swarm field-aligned and radial current densities using the dual-satellite method
parameter / type description
Timestamp
isotime
Time, UTC
Latitude
double
Position in ITRF, Latitude
Longitude
double
Position in ITRF, Longitude
Radius
double
Position in ITRF, Radius
IRC
double
Ionospheric radial current (IRC)
IRC_Error
double
uncertainty of IRC
FAC
double
Field-aligned current (FAC)
FAC_Error
double
uncertainty of FAC
Flags
integer
Flags characterizing the product quality (processing flags)
Flags_F
integer
Flags_F passed through from L1b and accumulated for quad points
Flags_B
integer
Flags_B passed through from L1b and accumulated for quad points
Flags_q
integer
Flags_q passed through from L1b and accumulated for quad points
dataset description
SW_OPER_TECATMS_2F Swarm A ionospheric total electron content
SW_OPER_TECBTMS_2F Swarm B ionospheric total electron content
SW_OPER_TECCTMS_2F Swarm C ionospheric total electron content
parameter / type description
Timestamp
isotime
Time stamp in UTC
Latitude
double
Geographic latitude
Longitude
double
Geographic longitude
Radius
double
Geographic radius
GPS_Position[3]
double
X-,Y-,Z-coordinates (WGS84) of the GPS satellite
LEO_Position[3]
double
X-,Y-,Z-coordinates (WGS84) of the LEO satellite
PRN
integer
GPS satellite PRN
L1
double
GPS L1 carrier phase observation
L2
double
GPS L2 carrier phase observation
P1
double
GPS P1 code phase observation
P2
double
GPS P2 code phase observation
S1
double
GPS signal-to-noise ratio or raw signal strength on L1
S2
double
GPS signal-to-noise ratio or raw signal strength on L2
Absolute_STEC
double
Absolute slant TEC
Absolute_VTEC
double
Absolute vertical TEC
Elevation_Angle
double
Elevation Angle
Relative_STEC
double
Relative slant TEC
Relative_STEC_RMS
double
Root mean square error of relative slant TEC
DCB
double
GPS receiver differential code bias
DCB_Error
double
Error of the GPS receiver differential code bias
dataset description
SW_OPER_IPDAIRR_2F Swarm A characteristics of the plasma density and plasma irregularities
SW_OPER_IPDBIRR_2F Swarm B characteristics of the plasma density and plasma irregularities
SW_OPER_IPDCIRR_2F Swarm C characteristics of the plasma density and plasma irregularities
parameter / type description
Timestamp
isotime
CDF_EPOCH of the measurement.
Latitude
double
Position in ITRF - Latitude.
Longitude
double
Position in ITRF - Longitude.
Radius
double
Position in ITRF - Radius.
Ne
double
Plasma density, directly copied from the Langmuir probe files.
Background_Ne
double
Background density, as calculated from Ne using a percentile filter of 551 datapoints (2 Hz raw data) and 35 as the percentile.
Foreground_Ne
double
Foreground density, as calculated from ndens using a percentile filter of 7 datapoints (2 Hz raw data) and 50 as the percentile.
Te
double
Electron temperature, directly copied from the Langmuir probe files.
PCP_flag
integer
The polar cap patch flag: 0 if the plasma density measurement occurred OUTSIDE a polar cap patch. 1 if the plasma density measurement occurred at one of the edges of a polar cap patch (no plasma velocity measurements are available). 2 if the plasma density measurement occurred at the LEADING edge of a polar cap patch. 3 if the plasma density measurement occurred at the TRAILING edge of a polar cap patch. 4 if the plasma density measurement occurred INSIDE a polar cap patch proper. When no ion drift data is available, the leading and trailing edges cannot be distinguished. In this case the polar cap patch flag is set to 4 throughout the patch proper and to 1 throughout both edges.
Grad_Ne_at_100km
double
The electron density gradient in a running window calculated via linear regression over 27 data points for the 2 Hz electron density data.
Grad_Ne_at_50km
double
The electron density gradient in a running window calculated via linear regression over 13 data points for the 2 Hz electron density data.
Grad_Ne_at_20km
double
The electron density gradient in a running window calculated via linear regression over 5 data points for the 2 Hz electron density data.
Grad_Ne_at_PCP_edge
double
The linear electron density gradient calculated over the edges of a patch. This variable is non-zero only at the edges of polar cap patches.
ROD
double
Rate Of change of Density
RODI10s
double
Rate Of change of Density Index (RODI) is the standard deviation of ROD over 10 seconds.
RODI20s
double
Rate Of change of Density Index (RODI) is the standard deviation of ROD over 20 seconds.
delta_Ne10s
double
Derived by subtracting Ne by its median filtered value in 10 seconds. As a result, delta_Ne10s indicates the electron density fluctuations smaller than 75 km.
delta_Ne20s
double
Derived by subtracting Ne by its median filtered value in 20 seconds. As a result, delta_Ne20s indicates the electron density fluctuations smaller than 150 km.
delta_Ne40s
double
Derived by subtracting Ne by its median filtered value in 40 seconds. As a result, delta_Ne40s indicates the electron density fluctuations smaller than 300 km.
Num_GPS_satellites
integer
Total number of tracked GPS satellites above 20 degrees.
mVTEC
double
Median of VTEC from all available GPS satellites above 30 degrees.
mROT
double
Median of Rate Of change of TEC (ROT) from all available GPS satellites above 30 degrees.
mROTI10s
double
Median of Rate Of change of TEC Index (ROTI) from all available GPS satellites above 30 degrees. The ROTI of each satellite is the standard deviation of ROT over 10 seconds.
mROTI20s
double
Median of Rate Of change of TEC Index (ROTI) from all available GPS satellites above 30 degrees. The ROTI of each satellite is the standard deviation of ROT over 20 seconds.
IBI_flag
integer
Plasma Bubble Index, copied from the level-2 Ionospheric Bubble Index product, IBIxTMS_2F.
Ionosphere_region_flag
integer
0: equator, 1: mid-latitudes; 2: auroral oval; 3: polar cap.
IPIR_index
integer
The numeric index for plasma fluctuations and irregularities: 0-3 low, 4-5 medium, and > 6 high level of ionosphericplasma irregularities.
Ne_quality_flag
integer
Quality flag for the Ne data and the derived data from Ne, e.g., background density, foreground density etc.
TEC_STD
double
STD of VTEC from all GPS satellites.
dataset description
SW_OPER_AEJALPL_2F Swarm A ionospheric sheet current densities determined by the Line Current (LC) method
SW_OPER_AEJBLPL_2F Swarm B ionospheric sheet current densities determined by the Line Current (LC) method
SW_OPER_AEJCLPL_2F Swarm C ionospheric sheet current densities determined by the Line Current (LC) method
parameter / type description
Timestamp
isotime
Time of observation, UTC
Latitude
double
Position in ITRF - Geocentric latitude
Longitude
double
Position in ITRF - Geocentric longitude
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic local time (QD)
J_NE[2]
double
North and East component of horizontal sheet current density vector in geocentric frame
J_QD
double
East component of horizontal sheet current density in QD frame
dataset description
SW_OPER_AEJALPL_2F:Quality Swarm A ionospheric sheet current densities determined by the Line Current (LC) method
SW_OPER_AEJBLPL_2F:Quality Swarm B ionospheric sheet current densities determined by the Line Current (LC) method
SW_OPER_AEJCLPL_2F:Quality Swarm C ionospheric sheet current densities determined by the Line Current (LC) method
parameter / type description
Timestamp
isotime
Time instants of quality information (RMS_misfit and Confidence), UTC
RMS_misfit
double
Root Mean Square error misfit between observations and model values for the oval crossings
Confidence
double
Goodness of fit computed as 1 - (residual rms / signal rms) for the oval crossings
dataset description
SW_OPER_AEJAPBL_2F Swarm A ionospheric auroral electrojet peaks and boundaries determined by the Line Current (LC) method
SW_OPER_AEJBPBL_2F Swarm B ionospheric auroral electrojet peaks and boundaries determined by the Line Current (LC) method
SW_OPER_AEJCPBL_2F Swarm C ionospheric auroral electrojet peaks and boundaries determined by the Line Current (LC) method
parameter / type description
Timestamp
isotime
Time of observation, UTC
Latitude
double
Geocentric latitude in ITRF
Longitude
double
Geocentric longitude in ITRF
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic local time (QD)
Flags
integer
Quality indicator
PointType
integer
Point Type
J_QD
double
Peak eastward sheet current intensity in QD frame
dataset description
SW_OPER_AEJALPS_2F Swarm A ionospheric sheet current densities determined by the Spherical Elementary Current Systems (SECS) method
SW_OPER_AEJBLPS_2F Swarm B ionospheric sheet current densities determined by the Spherical Elementary Current Systems (SECS) method
SW_OPER_AEJCLPS_2F Swarm C ionospheric sheet current densities determined by the Spherical Elementary Current Systems (SECS) method
parameter / type description
Timestamp
isotime
Time of observation, UTC
Latitude
double
Position in ITRF - Geocentric latitude
Longitude
double
Position in ITRF - Geocentric longitude
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic local time (QD)
J_CF_NE[2]
double
North and East component of the curl-free horizontal sheet current density vector in geocentric frame
J_DF_NE[2]
double
North and East component of the divergence-free horizontal sheet current density vector in geocentric frame
J_CF_SemiQD
double
North component of the curl-free horizontal sheet current density in SemiQD frame
J_DF_SemiQD
double
East component of the divergence-free horizontal sheet current density in SemiQD frame
J_R
double
Radial ionospheric current density at 110 km altitude in SemiQD frame
dataset description
SW_OPER_AEJALPS_2F:Quality Swarm A ionospheric sheet current densities determined by the Spherical Elementary Current Systems (SECS) method
SW_OPER_AEJBLPS_2F:Quality Swarm B ionospheric sheet current densities determined by the Spherical Elementary Current Systems (SECS) method
SW_OPER_AEJCLPS_2F:Quality Swarm C ionospheric sheet current densities determined by the Spherical Elementary Current Systems (SECS) method
parameter / type description
Timestamp
isotime
Time instants of quality information (RMS_misfit and Confidence), UTC
RMS_misfit
double
Root Mean Square error misfit between observations and model values for the oval crossing
Confidence
double
Goodness of fit computed as 1 - (residual rms / signal rms) for the oval crossing
dataset description
SW_OPER_AEJAPBS_2F Swarm A ionospheric auroral electrojet peaks and boundaries determined by the Spherical Elementary Current Systems (SECS) method
SW_OPER_AEJBPBS_2F Swarm B ionospheric auroral electrojet peaks and boundaries determined by the Spherical Elementary Current Systems (SECS) method
SW_OPER_AEJCPBS_2F Swarm C ionospheric auroral electrojet peaks and boundaries determined by the Spherical Elementary Current Systems (SECS) method
parameter / type description
Timestamp
isotime
Time of observation, UTC
Latitude
double
Geocentric latitude in ITRF
Longitude
double
Geocentric longitude in ITRF
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic local time (QD)
Flags
integer
Quality indicator
PointType
integer
Point Type
J_DF_SemiQD
double
Peak divergence-free sheet current density in SemiQD frame
dataset description
SW_OPER_AEJAPBS_2F:GroundMagneticDisturbance Swarm A ionospheric auroral electrojet peaks and boundaries determined by the Spherical Elementary Current Systems (SECS) method
SW_OPER_AEJBPBS_2F:GroundMagneticDisturbance Swarm B ionospheric auroral electrojet peaks and boundaries determined by the Spherical Elementary Current Systems (SECS) method
SW_OPER_AEJCPBS_2F:GroundMagneticDisturbance Swarm C ionospheric auroral electrojet peaks and boundaries determined by the Spherical Elementary Current Systems (SECS) method
parameter / type description
Timestamp
isotime
Time of peaks in ground magnetic field disturbance
Latitude
double
Geodetic latitude of peaks in ground magnetic field disturbance
Longitude
double
Geodetic longitude of peaks in ground magnetic field disturbance
B_NE[2]
double
Peak value of the ground magnetic field disturbance, geodetic NE frame
dataset description
SW_OPER_AOBAFAC_2F Swarm A aurora oval boundaries determined from the Field Aligned Current (FAC) data
SW_OPER_AOBBFAC_2F Swarm B aurora oval boundaries determined from the Field Aligned Current (FAC) data
SW_OPER_AOBCFAC_2F Swarm C aurora oval boundaries determined from the Field Aligned Current (FAC) data
parameter / type description
Timestamp
isotime
Time of observation, UTC
Latitude
double
Position in ITRF - Geocentric latitude
Longitude
double
Position in ITRF - Geocentric longitude
Radius
double
Position in ITRF - Geocentric radius (from the Earth center)
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic Local Time (QD)
Boundary_Flag
integer
Indicator for equatorward (=1) or poleward (=2) boundary
Quality[2]
double
Quality indicator of equatorward/poleward boundary (Pa, Sigma)
Pair_Indicator
integer
Indicator 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 0
dataset description
SW_OPER_MITA_LP_2F Swarm A mid-latitude ionospheric trough boundaries and minima from from Langmuir Probe (LP) data
SW_OPER_MITB_LP_2F Swarm B mid-latitude ionospheric trough boundaries and minima from from Langmuir Probe (LP) data
SW_OPER_MITC_LP_2F Swarm C mid-latitude ionospheric trough boundaries and minima from from Langmuir Probe (LP) data
parameter / type description
Timestamp
isotime
Time of observation, UTC
Counter[2]
integer
Swarm orbit counter and quarter orbit (four per Swarm orbit) counter
Latitude
double
Geocentric latitude in ITRF
Longitude
double
Geocentric longitude in ITRF
Radius
double
Geocentric radius in ITRF
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic local time (QD)
L_value
double
L-value
SZA
double
Solar zenith angle
Ne
double
LP electron density
Te
double
LP electron temperature
Depth
double
Depth of the MIT
DR
double
Relative change in density within the MIT
Width
double
Width of the MIT calculated from QD latitudes
dL
double
Width of the MIT calculated from L-values
PW_Gradient
double
Change in log electron density at the poleward wall of the MIT divided by QD latitude difference
EW_Gradient
double
Change in log electron density at the equatorward wall of the MIT divided by QD latitude difference
Quality[8]
integer
Characterizes the detection quality of the MIT as a whole
dataset description
SW_OPER_MITA_LP_2F:ID Swarm A mid-latitude ionospheric trough boundaries and minima from from Langmuir Probe (LP) data
SW_OPER_MITB_LP_2F:ID Swarm B mid-latitude ionospheric trough boundaries and minima from from Langmuir Probe (LP) data
SW_OPER_MITC_LP_2F:ID Swarm C mid-latitude ionospheric trough boundaries and minima from from Langmuir Probe (LP) data
parameter / type description
Timestamp
isotime
Time of observation, UTC
Counter[2]
integer
Swarm orbit counter and quarter orbit (four per Swarm orbit) counter
Latitude
double
Geocentric latitude in ITRF
Longitude
double
Geocentric longitude in ITRF
Radius
double
Geocentric radius in ITRF
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic local time (QD)
L_value
double
L-value
SZA
double
Solar zenith angle
Ne
double
LP electron density
Te
double
LP electron temperature
Position_Quality
integer
Indicator characterizing the detection quality of the position
PointType
integer
Point Type
dataset description
SW_OPER_MITATEC_2F Swarm A mid-latitude ionospheric trough boundaries and minima from from Total Electron Content (TEC) data
SW_OPER_MITBTEC_2F Swarm B mid-latitude ionospheric trough boundaries and minima from from Total Electron Content (TEC) data
SW_OPER_MITCTEC_2F Swarm C mid-latitude ionospheric trough boundaries and minima from from Total Electron Content (TEC) data
parameter / type description
Timestamp
isotime
Time of observation, UTC
Counter[2]
integer
Swarm orbit counter and quarter orbit (four per Swarm orbit) counter
Latitude
double
Geocentric latitude in ITRF
Longitude
double
Geocentric longitude in ITRF
Radius
double
Geocentric radius in ITRF
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic local time (QD)
L_value
double
L-value
SZA
double
Solar zenith angle
TEC
double
Total electron content
Depth
double
Depth of the MIT
DR
double
Relative change in density within the MIT
Width
double
Width of the MIT calculated from QD latitudes
dL
double
Width of the MIT calculated from L-values
PW_Gradient
double
Change in TEC at the poleward wall of the MIT divided by QD latitude difference
EW_Gradient
double
Change in TEC at the equatorward wall of the MIT divided by QD latitude difference
Quality[8]
integer
Characterizes the detection quality of the MIT as a whole
dataset description
SW_OPER_MITATEC_2F:ID Swarm A mid-latitude ionospheric trough boundaries and minima from from Total Electron Content (TEC) data
SW_OPER_MITBTEC_2F:ID Swarm B mid-latitude ionospheric trough boundaries and minima from from Total Electron Content (TEC) data
SW_OPER_MITCTEC_2F:ID Swarm C mid-latitude ionospheric trough boundaries and minima from from Total Electron Content (TEC) data
parameter / type description
Timestamp
isotime
Time of observation, UTC
Counter[2]
integer
Swarm orbit counter and quarter orbit (four per Swarm orbit) counter
Latitude
double
Geocentric latitude in ITRF
Longitude
double
Geocentric longitude in ITRF
Radius
double
Geocentric radius in ITRF
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic local time (QD)
L_value
double
L-value
SZA
double
Solar zenith angle
TEC
double
Total electron content
Position_Quality
integer
Indicator characterizing the detection quality of the position
PointType
integer
Point Type
dataset description
SW_OPER_PPIAFAC_2F Swarm A equatorward boundary of Small-Scale Field Aligned Currents (SSFAC) and the associated midnight Plasma-Pause (PP) index
SW_OPER_PPIBFAC_2F Swarm B equatorward boundary of Small-Scale Field Aligned Currents (SSFAC) and the associated midnight Plasma-Pause (PP) index
SW_OPER_PPICFAC_2F Swarm C equatorward boundary of Small-Scale Field Aligned Currents (SSFAC) and the associated midnight Plasma-Pause (PP) index
parameter / type description
Timestamp
isotime
Time of observation, UTC
Counter[2]
integer
Swarm orbit counter and quarter orbit (four per Swarm orbit) counter
Latitude
double
Geocentric latitude in ITRF
Longitude
double
Geocentric longitude in ITRF
Radius
double
Geocentric radius in ITRF
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic local time (QD)
L_value
double
L-value
SZA
double
Solar zenith angle
dL
double
Width of the MIT calculated from L-values
Sigma
double
Standard deviation of the linear fit of S at the boundary [RD-2]
PPI
double
Midnight Plasmapause index
Quality[7]
integer
Characterizes the detection quality of the MIT as a whole
dataset description
SW_OPER_PPIAFAC_2F:ID Swarm A equatorward boundary of Small-Scale Field Aligned Currents (SSFAC) and the associated midnight Plasma-Pause (PP) index
SW_OPER_PPIBFAC_2F:ID Swarm B equatorward boundary of Small-Scale Field Aligned Currents (SSFAC) and the associated midnight Plasma-Pause (PP) index
SW_OPER_PPICFAC_2F:ID Swarm C equatorward boundary of Small-Scale Field Aligned Currents (SSFAC) and the associated midnight Plasma-Pause (PP) index
parameter / type description
Timestamp
isotime
Time of observation, UTC
Counter[2]
integer
Swarm orbit counter and quarter orbit (four per Swarm orbit) counter
Latitude
double
Geocentric latitude in ITRF
Longitude
double
Geocentric longitude in ITRF
Radius
double
Geocentric radius in ITRF
Latitude_QD
double
Quasi-dipole latitude
Longitude_QD
double
Quasi-dipole longitude
MLT_QD
double
Magnetic local time (QD)
L_value
double
L-value
SZA
double
Solar zenith angle
Position_Quality
integer
Indicator characterizing the detection quality of the position
PointType
integer
Point Type

API Description

VirES server implements the version 3.0 of the HAPI Specification.

Example HAPI Queries

Data Request Limits

The time selection of one HAPI data request is currently limited to a time selection of approx. 432,000 data records (equivalent of 5 days of 1Hz MAGx_LR_1B data or 2 hours and 24 minutes of 50Hz MAGx_HR_1B data), which is the same limit as the one applied to the synchronous VirES API requests.

This number of records is converted to a time period by multiplication with the nominal cadence of the dataset (see x_maxTimeSelection in the dataset info) which is then used as the actual hard limit. For irregularly sampled datasets, the number of the actual records may slightly differ from the nominal limit.

If you need to retrieve more data than this limit, please consider splitting your large requests into smaller chunks.

Custom Extensions

The HAPI Specification allows extension of the protocol as long as these do not collide with the baseline specification and can be safely ignored by client which do not recognize them. The extension attributes are labelled by the x_ prefix.

The VirES extensions are described below...

Dataset Name and Type

The info responses contain extra x_dataset and x_datasetType for the VirES product collection (equal to the HAPI dataset name) and VirES product type. Datasets of the same x_datasetType bear the identical set of parameters.

Maximum Time Selection

The maximum time selection is included in the dataset info response as the custom x_maxTimeSelection field.

Storage Data Type

The parameters description contains additional attribute x_type publishing original storage data type of the parameter and its bit-size (int8, int16, int32, int64, uint8, uint16, uint32, uint64, float32 or float64).

In case of the time-stamps, the description defines the original time-encoding with these attributes: x_standard (UTC), x_epoch (zero-time instant, 1970-01-01T00:00:00Z), x_unit (time unit of the stored numbers, e.g. s, ms, or us) and x_type (storage data type, int64).

The string arrays contain an additional x_encoding attribute (ASCII or UTF-8).

Custom Binary Format

VirES provides an extra custom binary format x_binary. This format has the same structure and endianity as the HAPI binary format but the time, integer and floating point values are encoded in their source data type indicated by the x_type, rather than by the ISO‑8601 time string, 32‑bits signed integer and double precision float.

This binary format is a bit faster to produce, more compact than the standard binary format and it can safely represent uint32, int64, and uint64 values.

JSON Representation of Special IEEE 745 Values

The number representation in the JSON format is limited to decimal numbers (-123.456) with the optional exponential notation (-1.23456e2). JSON cannot represent the IEEE 745 special not-a-number and positive or negative infinity values which may occur in the provided time series data.

VirES for Swarm HAPI server encodes these values as strings which are parsable by the Javascript Number() and Python float() functions:

special valueJSON representation
not-a-number"NaN"
positive infinity"Infinity"
negative infinity"-Infinity"