A model of the deviation between IRI-2016 and ionospheric TEC observation based on GISTM at low latitude Indonesia region

Abstract

The diurnal variation pattern of total electron content(TEC) from the International Recurrence Ionosphere (IRI-2016) model is generally is good agreement with observational data at all latitudes. However, at low latitudes the IRI TEC is not as accurate as in midlatitudes. Some reports showed that the IRI-2016 TEC model at the maximum and minimum solar activities at low latitudes tends to be underestimate. In this paper, TEC from GISTM (GPS Ionospheric Scintillation and TEC Monitoring) that is installed at Pontianak station (0.03° S;109.33°E geomagnetic latitude 9.7°S ) used for validation and evaluation of IRI-2016 TEC model over the low latitude Indonesian sector. Data from the 2012 - 2014 period representing solar maximum and data from 2018 representing solar minimum, were used in this study. We also developed VTEC deviation (ΔTEC) model by using multiple linear regression and tested the model by using data 2019. Results show that IRI-2016 generally reproduces the diurnal variations pattern but underestimates the observation data for many hours each day especially during maximum solar activity 2012-20114. The highest deviation in the equinoctial months and lowest during the June and December solstice. The deviation (ΔTEC) model showed good agreement with observation data on January and December but not for other months especially on equinox months. Testing of the VTEC deviation model using 2019 data did not show significant improvement compared to the IRI-2016 itself, which generally produces good TEC prediction in most of the months except for equinox months.