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Data Access
FTPS from SPDF (not with most browsers)
HTTPS from SPDF (CDF)
HTTPS from SPDF (ASCII)
CDAWeb
WebService:
CDAWeb Programmatic Data Access
HAPI: CDAWeb HAPI Server
ISIS 2 CRC Electron Density Profiles
var authors='Jackson, John E.';
document.write(authors);
(2025).
ISIS 2 CRC Electron Density Profiles.
[Data set].
Space Physics Data Facility.
https://doi.org/10.48322/g9ry-hq05. Accessed on document.write(currentDateStr);.
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Copy BibTeX Citation
or other formats, should include the "Accessed on date" to identify the version of the resource being cited in a given publication.
ResourceID
spase://NASA/NumericalData/ISIS2/SFS/TOPS
Description
This data set, provided by the Communications Research Centre (CRC) in Ottawa, Canada, consists of electron density profiles for the ionosphere above the F2 maximum (topside ionosphere). The data are computed from digital values of frequency and virtual height, scaled from ionograms that are measured by the ISIS 2 (International Satellites for Ionospheric Studies) Swept-Frequency Sounder. The data are ordered chronologically. Telemetry stations are not identified, but satellite location, Greenwich mean time of observation, solar zenith angle at the satellite, dip latitude at the satellite, total electron content down to the lowest height of topside signal reflection (normally near 300 km), and other relevant information is noted with each profile. The format gives sequences of numbers for each point scaled from the ionogram. These sequences include electron density at the successive points, and the coefficients a2, b3, b4, b5, etc. from which geometric heights can be calculated, using formulas 40 and 41 in J. E. Jackson, "The reduction of topside ionograms to electron-density profiles," Proceedings of the IEEE., p. 960, June 1969. These formulas can also be used to calculate interpolated density-height values. A CRC interpolation program (available at NSSDC) can be used with this data set.
Format Description (ASCII):
+------------------------------------------------+
| M | I5 | number of records |
+------------------------------------------------+
each record consists of a header and then the electron density profile data
HEADER:
+------------------------------------------------+
|itype | I1 | spacecraft identifier |
|iquality | I2 | quality index* |
|date | I6 | yddd year and day of year |
|time | I6 | hhmmss hour minutes and seconds |
|long | F6.1 | longitude in degrees |
|lat | F6.2 | latitude in degrees |
|dip | F6.2 | magnetic inclination (IGRF) |
|L | F5.2 | L value |
|xhi | F6.1 | solar zenith angle at 100 km |
|Rz12 | I3 | 12-month-running mean of sunspot number |
|IG12 | I3 | 12-month-running mean of IG index |
|rtec | F6.2 | TEC found in data set (units?) |
|ln(NmF2) | F7.4 | IRI value for F2 peak in cm-3 |
|hmF2 | F5.1 | IRI value for F2 peak height in km |
|TEC_IRI | F6.2 | IRI value for TEC in TECU |
|n | I3 | number of data points |
+------------------------------------------------+
(*) Quality index ranges from 0 (best) to 10 (worst), actually 4 to 10 for these
data sets, with a most likely value of 6.
PROFILE DATA:
+---------------------------------------+
|n height values: | 14I5 | h/km*10 |
|n density values: | 10I7 | ln(Ne/cm-3)*100000 |
+---------------------------------------+
starting with the highest value (satellite height).
Metadata Rights
CC0-1.0:
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available SPASE metadata descriptions. The actual data/software may be subject to a different license.
View XML |
Edit
Details
Version:2.7.1
NumericalData
ResourceID
spase://NASA/NumericalData/ISIS2/SFS/TOPS
NamingAuthority
NASA
ResourceType
NumericalData
ResourceHeader
ResourceName
ISIS 2 CRC Electron Density Profiles
DOI
https://doi.org/10.48322/g9ry-hq05
ReleaseDate
2025-12-04 13:29:42Z
RevisionHistory
RevisionEvent
ReleaseDate
2021-04-27 16:38:11
Note
Initial release of metadata.
RevisionEvent
ReleaseDate
2025-06-30 16:47:56
Note
Added parameter descriptions, added information URL to the Jackson paper, added contact, added keywords, added more Description text, updated Access URL to point to the crc_ne_ascii and crc_ne_cdf directories, raised the description to 2.7.0. LNG
RevisionEvent
ReleaseDate
2025-09-10 15:38:11Z
Note
Revised ObservedRegions. JMW
RevisionEvent
ReleaseDate
2025-11-14 16:02:28Z
Note
Added PublicationInfo. Added ResourceType and NamingAuthority. Changed http to https in top-level schemaLocation attribute. Fixed version number separator in top-level schemaLocation attribute. ZCB
RevisionEvent
ReleaseDate
2025-12-04 13:29:42Z
Note
Added MetadataRightsList and RightsList(s). Updated to 2.7.1. ZCB
Description
This data set, provided by the Communications Research Centre (CRC) in Ottawa, Canada, consists of electron density profiles for the ionosphere above the F2 maximum (topside ionosphere). The data are computed from digital values of frequency and virtual height, scaled from ionograms that are measured by the ISIS 2 (International Satellites for Ionospheric Studies) Swept-Frequency Sounder. The data are ordered chronologically. Telemetry stations are not identified, but satellite location, Greenwich mean time of observation, solar zenith angle at the satellite, dip latitude at the satellite, total electron content down to the lowest height of topside signal reflection (normally near 300 km), and other relevant information is noted with each profile. The format gives sequences of numbers for each point scaled from the ionogram. These sequences include electron density at the successive points, and the coefficients a2, b3, b4, b5, etc. from which geometric heights can be calculated, using formulas 40 and 41 in J. E. Jackson, "The reduction of topside ionograms to electron-density profiles," Proceedings of the IEEE., p. 960, June 1969. These formulas can also be used to calculate interpolated density-height values. A CRC interpolation program (available at NSSDC) can be used with this data set.
Format Description (ASCII):
+------------------------------------------------+
| M | I5 | number of records |
+------------------------------------------------+
each record consists of a header and then the electron density profile data
HEADER:
+------------------------------------------------+
|itype | I1 | spacecraft identifier |
|iquality | I2 | quality index* |
|date | I6 | yddd year and day of year |
|time | I6 | hhmmss hour minutes and seconds |
|long | F6.1 | longitude in degrees |
|lat | F6.2 | latitude in degrees |
|dip | F6.2 | magnetic inclination (IGRF) |
|L | F5.2 | L value |
|xhi | F6.1 | solar zenith angle at 100 km |
|Rz12 | I3 | 12-month-running mean of sunspot number |
|IG12 | I3 | 12-month-running mean of IG index |
|rtec | F6.2 | TEC found in data set (units?) |
|ln(NmF2) | F7.4 | IRI value for F2 peak in cm-3 |
|hmF2 | F5.1 | IRI value for F2 peak height in km |
|TEC_IRI | F6.2 | IRI value for TEC in TECU |
|n | I3 | number of data points |
+------------------------------------------------+
(*) Quality index ranges from 0 (best) to 10 (worst), actually 4 to 10 for these
data sets, with a most likely value of 6.
PROFILE DATA:
+---------------------------------------+
|n height values: | 14I5 | h/km*10 |
|n density values: | 10I7 | ln(Ne/cm-3)*100000 |
+---------------------------------------+
starting with the highest value (satellite height).
Acknowledgement
Please acknowledge the NASA Space Physics Data Facility and the instrument's Principal Investigator for data usage.
PublicationInfo
Authors
Jackson, John E.
PublicationDate
2025-11-14 16:02:28Z
PublishedBy
Space Physics Data Facility
Contacts
Role
Person
StartDate
StopDate
Note
1.
FormerPI
spase://SMWG/Person/John.E.Jackson
2.
GeneralContact
spase://SMWG/Person/Elizabeth.D.Hewens
3.
GeneralContact
spase://SMWG/Person/Dieter.K.Bilitza
4.
MetadataContact
spase://SMWG/Person/Leonard.N.Garcia
InformationURL
Name
J. E. Jackson, "The reduction of topside ionograms to electron-density profiles", Proceedings of the IEEE., p. 960, June 1969
URL
https://doi.org/10.1109/PROC.1969.7140
Description
Landing page for the Jackson paper
InformationURL
Name
ISIS/Alouette Topside Sounder Data Restoration Project
URL
https://nssdc.gsfc.nasa.gov/space/isis/isis-status.html
Description
Website that provides access to additional background information, software, publications and images
PriorIDs
spase://VSPO/NumericalData/ISIS 2/SFS/NEPROF_TOPS
spase://VSPO/NumericalData/ISIS2/SFS/TOPS
AccessInformation
RepositoryID
spase://SMWG/Repository/NASA/GSFC/SPDF
Availability
Online
AccessRights
Open
RightsList
Rights
SchemeURI
https://spdx.org/licenses/
RightsIdentifierScheme
SPDX
RightsIdentifier
CC0-1.0
RightsURI
https://spdx.org/licenses/CC0-1.0.html
RightsName
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available NASA Heliophysics data products
AccessURL
Name
FTPS from SPDF (not with most browsers)
URL
ftps://spdf.gsfc.nasa.gov/pub/data/isis/topside_sounder/
AccessURL
Name
HTTPS from SPDF (CDF)
URL
https://spdf.gsfc.nasa.gov/pub/data/isis/topside_sounder/crc_ne_profile_cdf/isis2/
Description
In CDF via HTTP from CDAWeb
Format
CDF
AccessDirectoryTemplate
https://spdf.gsfc.nasa.gov/pub/data/isis/topside_sounder/crc_ne_profile_cdf/isis2/$Y/
AccessFilenameTemplate
i2_neprof_tops_$Y$m$d_v$v.cdf
AccessInformation
RepositoryID
spase://SMWG/Repository/NASA/GSFC/SPDF
Availability
Online
AccessRights
Open
RightsList
Rights
SchemeURI
https://spdx.org/licenses/
RightsIdentifierScheme
SPDX
RightsIdentifier
CC0-1.0
RightsURI
https://spdx.org/licenses/CC0-1.0.html
RightsName
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available NASA Heliophysics data products
AccessURL
Name
HTTPS from SPDF (ASCII)
URL
https://spdf.gsfc.nasa.gov/pub/data/isis/topside_sounder/crc_ne_profile_ascii/isis2_ne.asc
Description
ASCII Table
AccessURL
Name
CDAWeb
URL
https://cdaweb.gsfc.nasa.gov/cgi-bin/eval2.cgi?dataset=I2_NEPROF_TOPS&index=sp_phys
ProductKey
I2_NEPROF_TOPS
Description
I2_NEPROF_TOPS
Format
Text
AccessDirectoryTemplate
https://cdaweb.gsfc.nasa.gov/pub/data/isis/topside_sounder/crc_ne_profile_cdf/isis2/$Y
AccessFilenameTemplate
i2_neprof_tops_$Y$m$d_$v.cdf
AccessInformation
RepositoryID
spase://SMWG/Repository/NASA/GSFC/SPDF
Availability
Online
AccessRights
Open
AccessURL
Name
CDAWeb Programmatic Data Access
URL
https://cdaweb.gsfc.nasa.gov/WS/cdasr/1/dataviews/sp_phys/datasets/I2_NEPROF_TOPS/clientLibraryExample/
Style
WebService
ProductKey
I2_NEPROF_TOPS
Description
Access to this data from common programming environments. Note: this AccessInformation element was added by HDPWS.
Format
Binary
AccessInformation
RepositoryID
spase://SMWG/Repository/NASA/GSFC/SPDF
Availability
Online
AccessRights
Open
RightsList
Rights
SchemeURI
https://spdx.org/licenses/
RightsIdentifierScheme
SPDX
RightsIdentifier
CC0-1.0
RightsURI
https://spdx.org/licenses/CC0-1.0.html
RightsName
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available NASA Heliophysics data products
AccessURL
Name
CDAWeb HAPI Server
URL
https://cdaweb.gsfc.nasa.gov/hapi
Style
HAPI
ProductKey
I2_NEPROF_TOPS
Description
Web Service to this product using the HAPI interface.
Format
CSV
InstrumentIDs
spase://SMWG/Instrument/ISIS2/SFS
MeasurementType
Profile
TemporalDescription
TimeSpan
StartDate
1971-04-08 22:27:48
StopDate
1979-08-27 17:52:25
ObservedRegion
Earth.Magnetosphere
ObservedRegion
Earth.Magnetosphere.Polar
ObservedRegion
Earth.NearSurface
ObservedRegion
Earth.NearSurface.AuroralRegion
ObservedRegion
Earth.NearSurface.EquatorialRegion
ObservedRegion
Earth.NearSurface.Ionosphere
ObservedRegion
Earth.NearSurface.PolarCap
ObservedRegion
Earth.NearSurface.Ionosphere.Topside
Keywords
Ionosphere
Topside
Sounder
Ionogram
Parameter #1
Name
Time
ParameterKey
EPOCH
Description
Time
Units
ms
UnitsConversion
1.0e-3>s
Support
SupportQuantity
Temporal
Parameter #2
Name
satellite ID
ParameterKey
spacecraftID
Description
sat.-ID: 1=AL1, 2=AL2, 3=ISIS1, 4=ISIS2
Support
SupportQuantity
Other
Parameter #3
Name
Topside Ne in cm-3
ParameterKey
density
Description
Topside electon density in cm-3 from F peak to orbit altitude
Units
cm^-3
UnitsConversion
1.0e-3>m^-3
RenderingHints
AxisLabel
Ne
ValidMin
1.00
ValidMax
1e+09
FillValue
-9999.00
Particle
ParticleType
Electron
ParticleQuantity
NumberDensity
Parameter #4
Name
log(Ne/cm-3)
ParameterKey
log_density
Description
Logarithm (base 10) of topside Ne in cm-3
RenderingHints
AxisLabel
log(Ne/cm-3)
ValidMin
1.0000
ValidMax
9.0000
FillValue
-9.0000
Particle
ParticleType
Electron
ParticleQuantity
NumberDensity
Parameter #5
Name
TEC
ParameterKey
tec
Description
Total Electron Content in TECU (=1E16 m-2)
Units
1E16 m-2
RenderingHints
AxisLabel
TEC
ValidMin
0.00
ValidMax
500.00
FillValue
-1.E+31
Particle
ParticleType
Electron
ParticleQuantity
NumberDensity
Parameter #6
Name
TEC_IRI95
ParameterKey
tec_iri
Description
IRI-95 value for TEC in TECU (=1E16 m-2)
Units
1E16 m-2
RenderingHints
AxisLabel
TEC_IRI95
ValidMin
0.00
ValidMax
1000.00
FillValue
-1.0E+31
Particle
ParticleType
Electron
ParticleQuantity
NumberDensity
Parameter #7
Name
ln(NmF2_IRI/cm-3)
ParameterKey
IRI_F2peak
Description
IRI-95 value for the natural logarithm of the F2 peak in cm-3
Units
IRI-95
RenderingHints
AxisLabel
ln(NmF2/cm-3)
ValidMin
0.00
ValidMax
500.00
FillValue
-1.0E+31
Particle
ParticleType
Electron
ParticleQuantity
NumberDensity
Parameter #8
Name
hmF2 IRI-95
ParameterKey
IRI_F2peakHeight
Description
IRI-95 value for F2 peak in km
Units
km
UnitsConversion
1.0e+3>m
RenderingHints
AxisLabel
hmF2_IRI95
ValidMin
0.00
ValidMax
500.00
FillValue
-1.0E+31
Support
SupportQuantity
Positional
Parameter #9
Name
Num Data Points
ParameterKey
numDataPoints
Description
Number of data points per profile
Units
data points
RenderingHints
AxisLabel
Number of
ValidMin
1
ValidMax
999
Support
SupportQuantity
Other
Parameter #10
Name
Quality Index
ParameterKey
qualityIndex
Description
Quality Index (0-best, 10-worst)
RenderingHints
AxisLabel
Quality Index
ValidMin
0
ValidMax
10
FillValue
-1
Support
SupportQuantity
DataQuality
Parameter #11
Name
Longitude
ParameterKey
lon
Description
Longitude in degree (-180 to 180)
Units
degrees
UnitsConversion
0.01745>rad
RenderingHints
AxisLabel
Longitude
ValidMin
-180.0
ValidMax
180.0
FillValue
-1.0e+31
Support
SupportQuantity
Positional
Parameter #12
Name
Latitude
ParameterKey
lat
Description
Latitude in degree
Units
degrees
UnitsConversion
0.01745>rad
RenderingHints
AxisLabel
Latitude
ValidMin
-90.0
ValidMax
90.0
FillValue
-1.0e+31
Support
SupportQuantity
Positional
Parameter #13
Name
Magnetic Inclination
ParameterKey
dip
Description
Magnetic Inclination in degree
Units
degrees
UnitsConversion
0.01745>rad
RenderingHints
AxisLabel
Dip
ValidMin
-90.0
ValidMax
90.0
FillValue
-1.0e+31
Field
FieldQuantity
Magnetic
Parameter #14
Name
L value
ParameterKey
L
Description
L value
RenderingHints
AxisLabel
L value
ValidMin
0.0
ValidMax
180.0
FillValue
-1.0e+31
Field
FieldQuantity
Magnetic
Parameter #15
Name
Solar zenith angle
ParameterKey
sza
Description
Solar zenith angle at 100 km
Units
degrees
UnitsConversion
0.01745>rad
RenderingHints
AxisLabel
SZA
ValidMin
0.0
ValidMax
180.0
FillValue
-1.0e+31
Support
SupportQuantity
Positional
Parameter #16
Name
Rz12
ParameterKey
sunspotNumber
Description
12-month-running mean of sunspot number
RenderingHints
AxisLabel
Rz12
ValidMin
1
ValidMax
300
FillValue
-1
Support
SupportQuantity
Other
Parameter #17
Name
IG-12 index
ParameterKey
IGindex
Description
12-month-running mean of IG ionosonde index
RenderingHints
AxisLabel
IG-12
ValidMin
1
ValidMax
350
FillValue
-1
Support
SupportQuantity
Other
Parameter #18
Name
height
ParameterKey
height
Description
height
Units
km
UnitsConversion
1e+3>m
RenderingHints
AxisLabel
height
ValidMin
100.0
ValidMax
4000.0
FillValue
-9999.0
Support
SupportQuantity
Positional