Rate Of TEC Index at ground
This plot shows the average ROTI observed by a receiver on the ground. Large values in this plot will correspond to problems for ground systems in that region.
Timeline for disturbance on the ground
This plot shows one day, from midnight to midnight, of average ROTI at the ground for three region. The regions are:
  • Southern Norway, defined as 57 to 62 degrees North (blue line)
  • Middle Norway, defined as 62 to 67 degrees North (green line)
  • Northern Norway, defined as 67 to 72 degrees North (reed line)

Rate of TEC Index (ROTI)
This plot shows ROTI, which is a measure of ionospheric turbulence. Note that as the satellites are generally not located directly overhead, this map may not correspond exactly to the experience of a user on the ground. If this is what you are looking for, you must look at the 'Rate Of TEC Index at ground' plot.
Vertical Total Electron Content (VTEC)
This plot shows the plasma content of the ionosphere. A large plasma content does not necessarily cause problems, because the main effects can be corrected for by the use of dual-frequency equipment or support systems. Large variations of the plasma content in space and/or time may lead to problems for some systems. The plasma content is given in units of TEC Units (TECU). For further explanation of VTEC and TECU, see abbreviations.
Grid Ionospheric Vertical Error (GIVE)
This plot shows GIVE, which is a measure of the uncertainty of the corresponding VTEC values. For further explanation of GIVE, see abbreviations.
Amplitude Scintillation (S4) plots
This plot shows amplitude scintillation (S4) at the L1 frequency. The value for each square is the average value for all measurements in that square.
Phase Scintillation (Sigma_Phi) plots
This plot shows phase scintillation (Sigma_Phi) at the L1 frequency. The value for each square is the average value for all measurements in that square.
to the top

Due to data size and download time, download has been restricted to 48 hours of data in one chunk. If large amounts of data is required please contact the help desk.
VTEC data file format
2-dimensional VTEC grid data is available in two formats: IONEX and LonLatGrid. The data contained in both formats is exactly the same. The reason for the use of the second format is to also include GIVE data in the file, which is not supported by IONEX. The IONEX format is a standard format for exchange of ionospheric TEC maps. It is defined in the document "IONEX: The IONosphere Map Exchange Format Version" by Stefan Schaer and Werner Gurtner. This document can be found here: ftp://ics.gnsslab.cn/reports/formats/ionex1.pdf The LonLatGrid format is defined in this document: RTIM_FormatDescription_LonLatGrid.pdf For further explanation of VTEC, see the description of the VTEC plots and the abbreviation explanation.
GIVE data file format
2-dimensional GIVE grid data is available in the LonLatGrid format.The LonLatGrid format is defined in this document: RTIM_FormatDescription_LonLatGrid.pdf Note that the files also contain VTEC data. For further explanation of GIVE, see the description of the GIVE plots and the abbreviation explanation.
ROTI data files
2-dimensional ROTI grid data is available in the LonLatGrid format. The LonLatGrid format is defined in this document: RTIM_FormatDescription_LonLatGrid.pdf Note that the files contain two sets of grids;ROTI, which is the value of ROTI at the ionosphere altitude and ROTI_Ground, which is the mean ROTI observed by a receiver at the ground. For further explanation of ROTI, see the description of ROTI plots and the abbreviation explanation.
Scintillation data files
Scintillation data for individual IPPs is available in text (ASCII) files. There is one file per scintillation receiver per day. The files are named “nnnnYYYYDOY.scn”, where 'nnnn' is a four-letter code identifying the receiver, 'YYYY' is the year, and 'DOY' is the day-of-year. There are two versions of the format v1_1 is defined in RTIM_FormatDescription_Scintillation_v1_1.pdf and v1_2 is defined in RTIM_FormatDescription_Scintillation_v1_2.pdf
to the top

GIVE - Grid Ionospheric Vertical Error
GIVE is a measure of the uncertainty of a VTEC value. It is designed so that in 99.9% of the time, the actual error in VTEC will be smaller that the GIVE value.
GMT - Greenwich Mean Time
Greenwich Mean Time (GMT) is a time system originally referring to mean solar time at the Royal Observatory in Greenwich, London, which later became adopted as a global time standard.
GNSS - Global Navigation Satellite System
The generic name of a satellite system for positioning and navigation, with global coverage.
GPS - Global Positioning System
GPS is a GNSS owned and controlled by the US. Most of the signals are freely available for anyone to use.
IPP - Ionospheric Pierce Point
The coordinate of the intersection between the receiver-to-satellite line and the single layer ionosphere shell.
ROTI - Rate Of TEC Index
A measure of large-amplitude, small-scale changes in a plasma. In other words, a measure of plasma turbulence. A turbulent ionosphere causes serious disturbances of GNSS signals. This kind of disturbances is often impossible to correct for, and may lead to problems for all types of GNSS systems.ROTI is strongly related to scintillation, and may be viewed as a proxy for phase scintillation.
TECU - Total Electron Content Unit
A unit of plasma content. Defined to be 10^16 electrons per square meter.
UTC - Coordinated Universal Time
Coordinated Universal Time (UTC) is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time (GMT). For most purposes, UTC is synonymous with GMT, but GMT is no longer precisely defined by the scientific community.
VTEC - Vertical Total Electron Content
The height-integrated plasma content of the ionosphere. Normally given in units of TECU, which is defined as 10^16 electrons per square meter.
to the top

The ionosphere is the top layer of the atmosphere. It starts at an altitude of 50-100 km, depending on the level of sunlight and some other factors, and extends several hundreds of kilometers above this. The main difference between the ionosphere and the other atmospheric layers is that a large percentage of the gas is ionized. Ionized gas is also known as plasma.

Picture from NASA
to the top

Plasma is one of the fundamental states of matter. In a plasma one or more electrons have been separated from their atoms, for a large percentage of the atoms. Thus, a plasma consists to a large degree of positively and negatively charged particles that may move independently of each other. This results in some special properties, especially with respect to electric and magnetic fields. As satellite signals are electromagnetic waves, they can be strongly affected by the ionosphere.
to the top