PAS L2 Data Products

We produce 3 PAS Level-2 (L2; scientific data level) products in CDF (NASA’s Common Data Format) as follows.

3D velocity distribution function

e.g., solo_L2_swa-pas-vdf_YYYYMMDD_Vxx.cdf
1D energy differential flux

e.g., solo_L2_swa-pas-eflux_YYYYMMDD_Vxx.cdf
Ground moments

e.g., solo_L2_swa-pas-grnd-mom_YYYYMMDD_Vxx.cdf

where YYYYMMDD is the year, month, day of the data (e.g., 20220403) and Vxx is the version of the file (e.g., V02).

Tip

Visualization of SWA-PAS data are available through CLweb (http://clweb.irap.omp.eu/) and AMDA (http://amda.cdpp.eu/).

3D velocity distribution function data

In this section the CDF variables are shown in bold.

The 3D velocity distribution function CDF file consists of 3D arrays (variable “vdf”) of [11 azimuth, 9 elevations, 96 energies] of the ion number density in the phase space expressed in s \(^3\) m \(^{-6}\). Since the instant sampling may cover just a part of the full angular-energy range, the data record contains also the start and number of the elevation bins (“start_elevation”, “nb_elevation”), the start and number of the azimuth bins (“start_CEM”,”nb_CEM”), and the start and number of the energy bins (“start_energy”,”nb_energy”). User shall use only records of the categories (variable “Info”) as follows:

Normal sampling, one “vdf” each 4 sec
Snapshot sampling, “nb_K” VDFs per second
Burst sampling, “nb_K” VDFs per second

As of the version 2 (V02) of VDF data products, we have the following parameters.

Table 5.1 Brief description of parameters in the PAS 3D VDF file
Parameters	Description	Data type	Dimension
Azimuth	Center of CEM bins (azimuth)	CDF_REAL4	[11]
Elevation	Center of elevation bins	CDF_REAL4	[9]
Elevation_correction	Elevation correction for each energy	CDF_REAL4	[96]
Energy	Center of energy bins	CDF_REAL4	[96]
Epoch:	Epoch encoded as Terrestrial Time on rotating Earth geoid, ns since J2000	CDF_TIME_TT2000	[21314]
Full_azimuth	Full definition azimuth table	CDF_REAL4	[11, 9, 3]
Full_elevation	Full definition elevation table	CDF_REAL4	[11, 9, 3]
Half_interval	Acquisition half interval	CDF_REAL4	[21314]
Info	Info 0:Ground, 1:Normal, 2:Snapshot, 3:Burst, 4:Engineering, 5:Calib	CDF_UINT1	[21314]
PAS_to_RTN	PAS to RTN transformation matrix	CDF_REAL8	[21314, 3, 3]
SCET	Elapsed time on the onboard clock	CDF_REAL8	[21314]
delta_Elevation	Delta elevation table	CDF_REAL4	[9]
delta_m_Energy	Delta minus energy bins	CDF_REAL4	[96]
delta_p_Energy	Delta plus energy bins	CDF_REAL4	[96]
nb_CEM	CEM number	CDF_INT2	[21314]
nb_K	Number of sub-sampings per second	CDF_INT2	[21314]
nb_elevation	Number elevation bin	CDF_INT2	[21314]
nb_energy	Number energy bin number	CDF_INT2	[21314]
quality_factor	Data quality factor	CDF_REAL4	[21314]
start_CEM	Start CEM	CDF_INT2	[21314]
start_elevation	Start elevation bin	CDF_INT2	[21314]
start_energy	Start energy bin	CDF_INT2	[21314]
total_count	Total count	CDF_REAL4	[21314]
unrecovered_count	Unrecovered count	CDF_REAL4	[21314]
vdf	Velocity Distribution Function	CDF_REAL4	[21314, 11, 9, 96]

1D Differential Energy Flux

1D Differential Energy flux CDF file contain original velocity distribution function integrated over elevation and azimuth and converted to the differential energy flux. The value is expressed in cm \(^{-2}\) s \(^{-1}\) eV / eV. Since the instant sampling may cover just a part of the full energy range, the data record contains also the start and number of the energy bins (“start_energy”,”nb_energy”). User shall use only records of the categories (variable “Info”) as follows.

Normal sampling, one “eflux” each 4 sec
Snapshot sampling, “nb_K” efluxs per second
Burst sampling, “nb_K” efluxs per second

The brief description is in Table 5.2 below.

Table 5.2 Brief description of PAS 1D differential energy flux products
Parameters	Description	Data type	Dimension
Energy	Center of energy bins	CDF_REAL4	[96]
Epoch	Epoch encoded as Terrestrial Time on rotating Earth geoid, ns since J2000	CDF_TIME_TT2000	[21314]
Half_interval	Acquisition half interval	CDF_REAL4	[21314]
Info	Info 0:Ground, 1:Normal, 2:Snapshot, 3:Burst, 4:Engineering, 5:Calib	CDF_UINT1	[21314]
SCET	Elapsed time on the onboard clock	CDF_REAL8	[21314]
delta_m_Energy	Delta minus energy bins	CDF_REAL4	[96]
delta_p_Energy	Delta plus energy bins	CDF_REAL4	[96]
eflux:	Energy Flux (Omni-directional)	CDF_REAL4	[21314, 96]
nb_energy	Number energy bin number	CDF_INT2	[21314]
quality_factor	Data quality factor	CDF_REAL4	[21314]
start_energy	Start energy bin	CDF_INT2	[21314]
total_count	Total count	CDF_REAL4	[21314]
unrecovered_count	Unrecovered count	CDF_REAL4	[21314]

PAS Ground Moments

Ground moments contain the number density, the velocity vector, the pressure tensor and the temperature of the proton peak, extracted from the 3D VDF. User shall use only records of the categories (variable “Info”) as follows:

Normal sampling, one measurement each 4 sec
Snapshot sampling, “nb_K” measurements per second
Burst sampling, “nb_K” measurements per second

The “validity” flag shows the data quality. Do not use the data labeled as “1” since the number density and the pressure could be too low. Use the data labeled “2” with attention because the data could be noisy.

The brief description is in the Table 5.3 below.

Table 5.3 Brief description of PAS ground moments data
Parameters	Description	Data type	Dimension
Epoch	Epoch encoded as Terrestrial Time on rotating Earth geoid, ns since J2000	CDF_TIME_TT2000	[21314]
Half_interval	Acquisition half interval	CDF_REAL4	[21314]
Info	Info 0:Ground, 1:Normal, 2:Snapshot, 3:Burst, 4:Engineering, 5:Calib	CDF_UINT1	[21314]
N	Density in cm \(^{-3}\)	CDF_REAL4	[21314]
P_RTN	Pressure tensor in RTN frame	CDF_REAL4	[21314, 6]
P_SRF	Pressure tensor in SRF frame	CDF_REAL4	[21314, 6]
SCET	Elapsed time on the onboard clock	CDF_REAL8	[21314]
T	Temperature	CDF_REAL4	[21314]
TxTyTz_RTN	Temperature components (Tx, Ty, Tz) in RTN frame	CDF_REAL4	[21314, 3]
TxTyTz_SRF	Temperature components (Tx, Ty, Tz) in SRF frame	CDF_REAL4	[21314, 3]
V_RTN	Velocity in RTN frame	CDF_REAL4	[21314, 3]
V_SOLO_RTN	Solar Orbiter spacecraft velocity in RTN frame	CDF_FLOAT	[21314, 3]
V_SRF	Velocity in SRF frame	CDF_REAL4	[21314, 3]
quality_factor	Data quality factor	CDF_REAL4	[21314]
total_count	Total count	CDF_REAL4	[21314]
unrecovered_count	Unrecovered count	CDF_REAL4	[21314]