Impact of Filtering Methods in the Assessment of COSMIC Electron Density Profiles Over the Brazilian Region: Excluding Profiles With Negative Values Is the Best Strategy?
Year: 2025
Type: article
Abstract: Global Navigation Satellite Systems radio occultation (RO) is a valuable and relevant source of information from the atmosphere. Many efforts have been made to provide methods of validation of RO profiles, however, no clear methodology for filtering the profiles from RO can be easily found. In this study, we present strategies to filter RO electron density profiles over a low latitude region. Different methods are applied considering minimum values, manual filtering, range, and discrepancies with reference to the Chapman profile. The assessment is performed by means of ionosonde data for two years (2014–2015). The results show that assuming a minimum electron density limit slightly smaller than zero consistently with electron density estimation errors under very low actual values can provide significant improvements. In this study, the use of a − el/ limit led to better rates of retained profiles (65% vs. 32%) and a reduction in root mean square (RMS) (12% vs. 7%) compared to the exclusion of all profiles with negative values. When considering only electron density values above 100 km in altitude, there is still a significant loss of about 20% in the number of profiles with the same reference values (84% vs. 63%), with a similar performance in the RMS. The best performance is obtained with the strategies: range of occurrence (200–450 km) and the outliers identification (5 standard deviations limit), leading to a RMS reduction of about 26% and 19%, and a RMS reduction of 34% and 25%, respectively, while keeping 91% and 82% of the original profiles.
Source: Radio Science
DOI: 10.1029/2024rs008192
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,700
OpenAlex ID: W4416380394