High‐speed solar wind stream effects on the topside ionosphere over Arecibo: A case study during solar minimum. Issue 15 (11th August 2017)

• Record Type: Journal Article
• Authors: Hajra, Rajkumar; Tsurutani, Bruce T.; Brum, Christiano G. M.; Echer, Ezequiel
• Is Part Of: Geophysical research letters. Volume 44:Issue 15(2017)
• Page Start: 7607
• Page End: 7617
• Publication Date: 2017-08-11
• Subjects: topside ionosphere -- transition height -- solar wind -- HSS -- CIR -- EMIC waves; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL073805
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The impact of a high‐speed solar wind stream (HSS) on the topside near‐equatorial ionosphere (Arecibo: 28.17°N, L = 1.3) is investigated for the first time. Although the HSS did not lead to any significant geomagnetic storm activity, the ionosphere over Arecibo became hotter and expanded significantly in altitude as compared to a non‐HSS interval. The O + /H + transition height h T increased by ~200 km in the daytime and by ~100 km at night. At the h T, the peak ionospheric electron and ion temperatures increased by ~200–500 K during day and by ~50–70 K at night. While the O + ion concentration exhibited an overall enhancement, deep penetration of the H + ions below h T are observed during the day. The noontime peak electron density was ~4 times higher during the HSS event compared to the non‐HSS interval. We present three possible mechanisms to explain this topside ionospheric heating. Key Points: Impact of an interplanetary high‐speed solar wind stream (HSS) on the near‐equatorial topside ionosphere is studied for the first time The topside ionosphere expanded in altitude (100‐200 km) and became hotter (50–500 K) during the HSS The electron density of the topside ionosphere increased by a factor of ~4 during the HSS compared to a non‐HSS interval