TEC

About: TEC is a research topic. Over the lifetime, 5119 publications have been published within this topic receiving 84696 citations.

Validation of the IRI-2012 model with GPS-based ground observation over a low-latitude Singapore station

Abstract: The ionospheric total electron content (TEC) in the low-latitude Singapore region (geographic latitude 01.37° N, longitude, 103.67° E, geomagnetic latitude 8.5° S) for 2010 to 2011 was retrieved using the data from global positioning system (GPS)-based measurements. The observed TEC from GPS is compared with those derived from the latest International Reference Ionosphere (IRI)-2012 model with three options, IRI-Nequick (IRI-Neq), IRI-2001, and IRI-01-Corr, for topside electron density. The results showed that the IRI-Neq and IRI-01-Corr models are in good agreement with GPS-TEC values at all times, in all seasons, for the year 2010. For the year 2011, these two models showed agreement at all times with GPS-TEC only for the summer season, and for the period 11:00 to 24:00 UT hours (19:00 to 24:00 LT and 00:00 to 08:00 LT) during the winter and equinox seasons. The IRI-2012 model electron density profile showed agreement with constellation observing system for meteorology, ionosphere, and climate (COSMIC) radio occultation (RO)-based measurements around 250 to 300 km and was found to be independent of the options for topside density profiles. However, above 300 km, the IRI-2012 model electron density profile does not show agreement with COSMIC measurements. The observations (COSMIC and GPS) and IRI-2012-based data of TEC and electron density profiles were also analyzed during quiet and storm periods. The analysis showed that the IRI model does not represent the impact of storms, while observations show the impact of storms on the low-latitude ionosphere. This suggests that significant improvements in the IRI model are required for estimating behavior during storms, particularly in low-latitude regions.

Measuring Ionospheric Scintillation Effects from GPS Signals

Abstract: GPS signals provide an excellent means for measuring ionospheric scintillation effects on a global basis because the signals are continuously available and can be measured through many points of the ionosphere simultaneously. GPS signals are themselves affected. However, tracking through disturbances with a GPS receiver is usually possible with reasonably wide bandwidth tracking loops. Because of this, ionospheric scintillation can be monitored, and is currently being monitored around the world. This was not widely possible during the last solar activity peak. The importance of the wide bandwidth is that scintillation parameters, such as spectral content, can be computed, not just the effects of the scintillation on GPS receiver performance. The majority of the current wide bandwidth monitoring is being done using a commercially off-the-shelf GPS receiver implemented with special software -- the GSV4000 GPS Ionospheric Scintillation Monitor (GISM) and predecessor prototype units. Now, GPS Silicon Valley is pleased to offer the new GSV4004 GPS Ionospheric Scintillation and TEC Monitor (GISTM) receiver. This receiver, a NovAtel EURO4 dual-frequency receiver with special firmware, comprises the major component of a GPS signal monitor, specifically configured to measure amplitude and phase scintillation from the L1 frequency GPS signals, and the ionosphere's TEC from the L1 and L2 frequency GPS signals. This scintillation and TEC monitoring receiver is housed in a NovAtel GPStation4E housing with a low phase noise oscillator, and provides true amplitude, single frequency carrier phase measurements and TEC measurements of up to 11 GPS satellites in view. It will also track one SBAS (WAAS, EGNOS or MSAS) satellite, providing L1 measurements and data, as the 12th satellite. The unit comes with complete software that allows the automatic measurement and computation of all the major scintillation parameters and TEC. A variety of antennae, with or without choke rings and cables, are offered as options. In this paper, the wide bandwidth monitoring capabilities of these receivers are described. This is followed by the presentation of data collected from a selection of recorded scintillation events and TEC calibration results.