PPIxFAC (Plasmapause boundary)

PPIxFAC (Plasmapause boundary)#

Abstract: Access to the PPIxFAC product from the PRISM project. This gives information about the boundaries of small-scale field-aligned currents (SSFAC) and the associated midnight plasmapause (PP) index.

Collection information#

The dataset is split over a default collection, and a subcollection:

SW_OPER_PPIxFAC_2F contains the plasmapause index (PPI)
SW_OPER_PPIxFAC_2F:ID identifies boundaries of SSSFAC (see PointType)

Collections available:

Collection	Dataset
`SW_OPER_PPIAFAC_2F`	Swarm A PPI and SSFAC boundaries
`SW_OPER_PPIAFAC_2F:ID`	Swarm A edges of the SSFAC boundaries (“ID” dataset)
`SW_OPER_PPIBFAC_2F`	Swarm B PPI and SSFAC boundaries
`SW_OPER_PPIBFAC_2F:ID`	Swarm B edges of the SSFAC boundaries (“ID” dataset)
`SW_OPER_PPICFAC_2F`	Swarm C PPI and SSFAC boundaries
`SW_OPER_PPICFAC_2F:ID`	Swarm C edges of the SSFAC boundaries (“ID” dataset)

Available “measurements” in each collection type:

request = SwarmRequest()
print("PPIxFAC variables:\n", request.available_measurements("SW_OPER_PPIAFAC_2F"))
print("PPIxFAC:ID variables:\n", request.available_measurements("SW_OPER_PPIAFAC_2F:ID"))

PPIxFAC variables:
 ['Counter', 'Latitude_QD', 'Longitude_QD', 'MLT_QD', 'L_value', 'SZA', 'Sigma', 'PPI', 'dL', 'Quality']
PPIxFAC:ID variables:
 ['Counter', 'Latitude_QD', 'Longitude_QD', 'MLT_QD', 'L_value', 'SZA', 'Position_Quality', 'PointType']

\[R_E\]

`SW_OPER_PPIxFAC_2F`#

VirES Variable	Source Product Variable	Unit	Dimension	Description
`Counter`	`Counter`	$$-$$	vector[2]	Swarm orbit and quarter orbit counters
`Timestamp`	`Timestamp`	$$-$$	scalar	UTC time of the SSFAC boundary
`Latitude`	`Latitude`	$$\text{deg}$$	scalar	ITRF geocentric latitude of the SSFAC boundary
`Longitude`	`Longitude`	$$\text{deg}$$	scalar	ITRF geocentric longitude of the SSFAC boundary
`Radius`	`Radius`	$$\text{m}$$	scalar	ITRF geocentric radius of the SSFAC boundary
`Latitude_QD`	`Latitude_QD`	$$\text{deg}$$	scalar	Quasi-dipole latitude of the SSFAC boundary
`Longitude_QD`	`Longitude_QD`	$$\text{deg}$$	scalar	Quasi-dipole longitude of the SSFAC boundary
`MLT_QD`	`MLT`	$$\text{hour}$$	scalar	Magnetic local time (QD) of the SSFAC boundary
`L_value`	`L_value`	$$-$$	scalar	L-value in earth radii of the SSFAC boundary
`SZA`	`SZA`	$$\text{deg}$$	scalar	Solar zenith angle of the SSFAC boundary
`Sigma`	`Sigma`	$$-$$	scalar	Standard deviation of the linear fit of S at the boundary
`PPI`	`PPI`	$$R_E$$	scalar	midnight plasmapause index
`dL`	`dL`	$$\text{deg}$$	scalar	boundary width in Earth radii
`Quality`	`Quality`	$$-$$	vector [7]	Quality indicators of SSFAC boundary detection

The Quality vector flags contain integer values from -1 to 3 indicating the quality of the MIT as a whole. Positive values indicate good or acceptable observation, while -1 means a likely false observation. For all flags, a 0 value means that the information needed to derive the flag is not available. In general, greater numbers indicate higher quality. For more details, see the product documentation.

`SW_OPER_PPIxFAC_2F:ID`#

VirES Variable	Source Product Variable	Unit	Dimension	Description
`Counter`	`Counter`	$$-$$	vector[2]	Swarm orbit and quarter orbit counters
`Timestamp`	`Timestamp_ID`	$$-$$	scalar	UTC time of the observation
`Latitude`	`Latitude_ID`	$$\text{deg}$$	scalar	ITRF geocentric latitude
`Longitude`	`Longitude_ID`	$$\text{deg}$$	scalar	ITRF geocentric longitude
`Radius`	`Radius_ID`	$$\text{m}$$	scalar	ITRF geocentric radius
`Latitude_QD`	`Latitude_QD_ID`	$$\text{deg}$$	scalar	Quasi-dipole latitude
`Longitude_QD`	`Longitude_QD_ID`	$$\text{deg}$$	scalar	Quasi-dipole longitude
`MLT_QD`	`MLT_ID`	$$\text{hour}$$	scalar	Magnetic local time (QD)
`L_value`	`L_value_ID`	$$-$$	scalar	L-value in earth radii
`SZA`	`SZA_ID`	$$\text{deg}$$	scalar	Solar zenith angle
`Position_Quality`	`Position_Quality_ID`	$$-$$	scalar	detection quality of each single position
`PointType`	n/a	$$-$$	scalar	point type derived from the source `*_ID` column

Position_Quality describes the overall quality of the corresponding boundary/position. The possible values and their meaning are 3: highest quality; 2: fair quality; 1: uncertain detection; -1: a likely false positive detection; -2: the corresponding boundary/position is not defined. For more details, see the product documentation.

These are the possible PointType values for the PPIxFAC_2F products:

Value	Hex.	Bin.	ID Column	Meaning
0	0x0	0b0000	1	equatorward edge of SSFAC boundary
1	0x1	0b0001	2	poleward edge of SSFAC boundary

PPIxFAC example#

start = dt.datetime(2016, 1, 1)
end = dt.datetime(2016, 1, 8)

def attach_missing_units(data, ds):
    """TO FIX"""
    with data.contents[0].open_cdf() as cdf:
        for data_var in ds.data_vars:
            units = cdf.varattsget(data_var).get("UNIT", "-")
            ds[data_var].attrs["units"] = units
    return ds

fig, axes = plt.subplots(nrows=2, ncols=1, figsize=(10, 5), sharex=True)
_equatorward = ds_id.where(ds_id["PointType"] == 0, drop=True)
_poleward = ds_id.where(ds_id["PointType"] == 1, drop=True)
axes[0].plot(_equatorward["Timestamp"], _equatorward["QDLat"], color="grey", linestyle="--")
axes[0].plot(_poleward["Timestamp"], _poleward["QDLat"], color="grey", linestyle="--")
axes[0].plot(ds["Timestamp"], ds["QDLat"], color="black", linestyle="-")
axes[1].plot(ds["Timestamp"], ds["PPI"])
axes[0].set_ylim(40, 90)
axes[0].set_title("Boundaries of SSFAC")
axes[0].set_ylabel("QDLat")
axes[1].set_title("Plasmapause index")
axes[1].set_ylabel("PPI [$R_E$]")
axes[0].grid()
axes[1].grid()

../_images/f174ab86077279e48632d94f84534e0356914210b0870df427536a3e6ad0056c.png

VirES Variable	Source Product Variable	Unit	Dimension	Description
`Counter`	`Counter`	$\(-\)$	vector[2]	Swarm orbit and quarter orbit counters
`Timestamp`	`Timestamp`	$\(-\)$	scalar	UTC time of the SSFAC boundary
`Latitude`	`Latitude`	$\(\text{deg}\)$	scalar	ITRF geocentric latitude of the SSFAC boundary
`Longitude`	`Longitude`	$\(\text{deg}\)$	scalar	ITRF geocentric longitude of the SSFAC boundary
`Radius`	`Radius`	$\(\text{m}\)$	scalar	ITRF geocentric radius of the SSFAC boundary
`Latitude_QD`	`Latitude_QD`	$\(\text{deg}\)$	scalar	Quasi-dipole latitude of the SSFAC boundary
`Longitude_QD`	`Longitude_QD`	$\(\text{deg}\)$	scalar	Quasi-dipole longitude of the SSFAC boundary
`MLT_QD`	`MLT`	$\(\text{hour}\)$	scalar	Magnetic local time (QD) of the SSFAC boundary
`L_value`	`L_value`	$\(-\)$	scalar	L-value in earth radii of the SSFAC boundary
`SZA`	`SZA`	$\(\text{deg}\)$	scalar	Solar zenith angle of the SSFAC boundary
`Sigma`	`Sigma`	$\(-\)$	scalar	Standard deviation of the linear fit of S at the boundary
`PPI`	`PPI`	$\(R_E\)$	scalar	midnight plasmapause index
`dL`	`dL`	$\(\text{deg}\)$	scalar	boundary width in Earth radii
`Quality`	`Quality`	$\(-\)$	vector [7]	Quality indicators of SSFAC boundary detection

PPIxFAC (Plasmapause boundary)

Contents

PPIxFAC (Plasmapause boundary)#

Collection information#

SW_OPER_PPIxFAC_2F#

SW_OPER_PPIxFAC_2F:ID#

PPIxFAC example#

`SW_OPER_PPIxFAC_2F`#

`SW_OPER_PPIxFAC_2F:ID`#