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HartRAO Geodata

GNSS Basestation Velocities

Global Navigation Satellite System (GNSS) basestations using signals from GPS and GLONASS measure positions at cm levels and so show tectonic plate motion when monitored on long timescales.

HartRAO and collaborators operate base stations used by the International Global Navigation Satellite System Service (IGS) that are listed below.

Precipitable Water Vapour

GNSS data are used to measure the Total Zenith Delay (TZD) in the arrival time of signals from the satellites at the base station. This is corrected for local air pressure and temperature variations to derive the Precipitable Water Vapour (PWV) content of the atmosphere.

HartRAO (station code HRAO) data are processed by SuomiNet. To download data recorded at 30 minute intervals from global sites processed by SUOMINET, start at SuomiNet - data. All their global stations will be downloaded, they are stored in one file per day. Data for wanted stations can be extracted by searching for their station codes.

Ionospheric Total Electron Content

GPS base station data can also be processed to derive the Total Electron Content (TEC) of the ionosphere from the difference in arrival times of the two frequencies transmitted by the satellites.

JPL produces real-time maps of the TEC from a global array of GPS stations, including those operated by the HartRAO Space Geodesy team at Hartebeesthoek and at Sutherland.

Tide Gauge Data

These data are processed by the Intergovernmental Oceanographic Commission of UNESCO (IOC).

Radio Telescope Position Velocities

Radio telescopes operating in global networks have their positions determined by using distant radio-emitting galaxies as fixed beacons in space. Plate tectonic motion makes these positions change over time. The most recent velocity solution is from NASA's Goddard Spaceflight Centre. More plots can be selected at GSFC VLBI NUVEL Solution 2007dn. For technical data see the GSFC VLBI Data and Results page.

Geodetic Data from HartRAO

GNSS, SLR, Geodetic VLBI data from HartRAO are archived and made available by the Crustal Dynamics Data Information System CDDIS at NASA's Goddard Spaceflight Centre.