Ne Gradient Ionosphere indeX (NEGIX)
The NEGIX measures the spatial Ne gradients in the topside ionosphere (Swarm up to GNSS orbit) using GNSS Precise Orbit Determination (POD) measurements using Swarm onboard Langmuir probe (LP) measurements (using 2 Hz data).
Sample Data
Global NEGIX
NEGIX for Europe
Product Specification
One data file in CDF format is produced per day since also daily input electron density files are used for the determination of NEGIX. The maximum length of the produced array corresponds to the resolution of the input data, meaning a maximum of 172800 measurements, or 2Hz sampling rate. However, the resolution of NEGIX finally will depend on the suggested combination of measurements.
As follows, a description of the expected output variables is presented:
Variable name | Description | Type | Unit |
Timestamp | Time in Universal Time | CDF_EPOCH | ns |
Longitude | Position of NEGIX (X, Y) in geocentric longitude. Averaged longitude position of many central points (CPs) derived from the combination of Ne measurements of Swarm-A and C | CDF_DOUBLE | deg |
Latitude | Position of NEGIX (X, Y) in geocentric latitude. Averaged latitude position of many central points (CPs) derived from the combination of Ne meas-urements of Swarm-A and C | CDF_DOUBLE | deg |
NEGIX X | Value of NEGIX for the East-West component as defined in equation 22 | CDF_DOUBLE | electron cm-3 km-1 |
NEGIX Y | Value of NEGIX for the North-South component as defined in equation 23 | CDF_DOUBLE | electron cm-3 km-1 |
Total NEGIX | Total value of NEGIX as defined in equation 21 | CDF_DOUBLE | electron cm-3 km-1 |
Flags NEGIX | Flags characterizing the dispersion of Ne-gradient values within a given spatial resolution that are used to compute the total vector | CDF_UINT4 |
Sample data can be found in the archive.