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IONMON Archive
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The ESA/ESOC Navigation Support Office delivers animations of Total Electron Content (TEC) & TEC Root Mean Square errors (RMS) global maps. The animations cover 24 hours with 1-hour time resolution. TEC and RMS levels are displayed in TEC units (1 TECU = 1016 el/m2) on the colour maps animations. The colour bars, displayed underneath the maps, are fixed from 0 to 60 TECU for TEC and from 0 to 10 TECU for RMS. In case TEC and RMS values exceed the aforementioned fixed limits, the maximum value will be reported next the colour bar.

TEC and RMS maps are computed with a single layer approach (IONMON Version 1), taking slant range TEC observables derived from dual-frequency GPS and GLONASS data, whereby ionospheric TEC is modelled by spherical harmonics in combination with a daily Differential Code Biases (DCBs) fitting. In this single layer approach, the ionospheric TEC is assumed to be condensed on a hollow sphere enveloping the Earth at an altitude of 450 km. On that sphere, the global TEC distribution is then described by a degree and order 15 spherical harmonics function. The function coefficients are determined from GPS and GLONASS dual-frequency data recorded at maximum 300 globally distributed (typically 220 - 240) ground sites. Model-internal, all computations are conducted in a solar-geomagnetic reference system. References: J. Feltens (2007) and J. Feltens et al. (2011)

These movies are processed once per day, and new daily movies are typically available shortly after 10H UTC. Please note that a new processing scheme was implemented in September 2017, and movies prior to this date may not be fully consistent. For this reason, movies preceding this date are provided for illustrative purposes only, and should not considered definitive.

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