Assimilating ground-based GNSS-derived TEC data into NeQuick at low latitudes

NAVA BRUNO; MORAES SANTOS PIRES; KASHCHEYEV ANTON; AZPILICUETA FRANCISCO

Boston

Simposio; Beacon Satellite Symposyum; 2022

Boston College - ICTP

In this work, the results obtained through the implementation of the Best Linear Unbiased Estimator (BLUE) algorithm to assimilate low-latitude, ground-based, GNSS-derived Total Electron Content (TEC) data into NeQuick are presented. NeQuick being a model conceived to reproduce the behaviour of the ionospheric electron density in a climatological way, it has been used as a background in the assimilation procedure. TEC data for the days 15 and 16 July 2017 from about 200 receivers located in the South American continent have been assimilated. Manually scaled ionosphere peak parameter values obtained at one-hour time interval from Boa Vista, Cachoeira Paulista, Campo Grande, and Fortaleza ionosondes have been considered as “ground truth” measurements for the validation of the assimilation scheme. In terms of geomagnetic activity, the 15th corresponds to a quiet period, while the 16th can be considered slightly disturbed (with the Dst index reaching a minimum of -72 nT). From the data analysis, during the day 16 it is possible to notice a TEC decrease in relation to the southern peak of the Equatorial Ionization Anomaly region if compared to the day 15, while a slight increase can be observed otherwise. The statistical results, based on the relative frequency distribution of the differences between the retrieved and the corresponding experimental peak parameter values, confirm the effectiveness of the BLUE algorithm for assimilating ground-based GNSS-derived TEC data, especially during the geomagnetically disturbed day. This is substantiated by the reduced average and standard deviation errors in the reconstructed foF2, if compared to the analogous errors for the NeQuick model used as a background, and by the fact that the error reduction is more remarkable during the disturbed day.