Realtime GNSS TEC

[npcalyen]

Hello,
Could you provide detailed guidance including examples, on how to calculate TECu from realtime GNSS CSV files? I have no idea how to proceed and greatly need assistance with step-by-step instructions.

Thanks in advance.

https://cddis.nasa.gov/archive/gnss/products/realtime/jpl_ionosphere/2024/
sample data :
GPSSoD, UTCTime, sat, ipplat, ipplon, atec, stec, dataflag
49555, 240504134537, C005I, 32.76959, 46.34834, -100.60362, 0.075012238,0
49560, 240504134542, C005I, 32.7717, 46.34699, -100.642869, 0.071028156,0
...

[CDDIS_support_Rebecca]

We will contact the creators of these files and ask them for guidance.

[CDDIS_support_Rebecca]

The creator of these files shared the following information. Please let us know if you need further assistance.

File Format: CSV. Fields and corresponding description:
- GPSSoD the GPS seconds of day (i.e., seconds since midnight on the day of the file)
- UTCTime the UTC time in YYmmDDHHMMSS format (taking UTC leap seconds into account; with YY the 2-digit year, mm the 2-digit month, DD the 2-digit day, HH the 2-digit hours, MM the 2-digit minutes, and SS the 2-digit seconds
- sat the satellite Space Vehicle Number (SVN)
- ipplat the latitude of the ionospheric pierce point (IPP) for the link between the site (<SITE> of the corresponding file) and the satellite (sat field)
- ipplon the longitude of the ionospheric pierce point (IPP) for the link between the site (<SITE> of the corresponding file) and the satellite (sat field)
- atec absolute (uncalibrated and unfiltered) slant TEC (Total Electron Content) along the line of sight between the site (<SITE> of the corresponding file) and the satellite (sat field)
- stec filtered (high-pass with a 15-min cut-off period) TEC (Total Electron Content) along the line of sight between the site (<SITE> of the corresponding file) and the satellite (sat field)
- dataflag informative flag about this particular data point: - 0 = nothing to report - 5 = interpolated data point, due to a data gap - 1X, 3X = a cycle slip was detected but not corrected; with: X = 1 or 2 if slip detected on carrier phase 1 or 2 (respectively), X = 3 if detected on both carrier phases - 2X, 4X = a cycle slip was detected and a correction was attempted; with: X = 1 or 2 if slip detected on carrier phase 1 or 2 (respectively), X = 3 if detected on both carrier phases

Format Link: https://datatracker.ietf.org/doc/html/rfc4180 (CSV)

[npcalyen]

Dear Rebecca,
Thank you, but unfortunately that's not the answer I'm looking for. I have sent you an email with the details of my query.

I would appreciate it if you could redirect my question to the relevant individuals after checking, please.

[drdgl]

Did this question ever get a more detailed answer about how one would use this data? For example, the atec and stec fields are sometimes negative where as TEC is positive. Is that due to a per site bias that needs to be calibrated? The scale of the tec fields are different by about 3 orders of magnitude. What are the units of each? The atec definition says slant TEC but the stec definition does not. Is the stec a vertical TEC? To be able to use a slant TEC, one would need to know the obliquity factor. The location of the sites and the satellites are not provided. Thanks in advance for any tips on how to convert this data into a vertical TEC value at the provided pierce point.

[CDDIS - rlimbach]

The people best able to answer your questions are Siddharth Krishnamoorthy (Siddharth.Krishnamoorthy@jpl.nasa.gov) and Camille Martire (camille.martire@jpl.nasa.gov).