LAUSR

Abstract. In this work we analyze the ionograms obtained by the recent digisonde installed in Santa Maria (29.7 ∘  S, 53.7 ∘  W, dip angle  = − 37 ∘ ), Brazil, to calculate the monthly averages of the F2 layer critical frequency (foF2), its peak height (hmF2), and the E-region critical frequency (foE) acquired during geomagnetically quiet days from September 2017 to August 2018. The monthly averages are compared to the 2016 version of the International Reference Ionosphere (IRI) model predictions in order to study its performance close to the center of the South America Magnetic Anomaly (SAMA), which is a region particularly important for high-frequency (HF) ground-to-satellite navigation signals. The foF2 estimated with the Consultative Committee International Radio (CCIR) and International Union of Radio Science (URSI) options makes good predictions throughout the year, whereas, for hmF2, it is recommended to use the SHU-2015 option instead of the other available options (AMTB2013 and BSE-1979). The IRI-2016 model outputs for foE and the observations presented very good agreement.