Solar flare effects observed over Jicamarca during MST-ISR experiments

MST radar;IS radar;solar flare;solar flare effects;Jicamarca Radio Observatory;mesosphere-stratosphere-troposphere (MST)

Reyes, Pablo ; Kudeki ; Erhan

关键词: MST radar;    IS radar;    solar flare;    solar flare effects;    Jicamarca Radio Observatory;    mesosphere-stratosphere-troposphere (MST);   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/31196/Reyes_Pablo.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

A study of solar flare effects observed at the Jicamarca Radio Observatory (JRO) will be presented. The observations were made while the Jicamarca radar was conducting combined observations in mesosphere-stratosphere-troposphere (MST) and incoherent scatter radar (ISR) modes. Combined MST-ISR campaigns have been conducted at JRO from December 2004 until January 2009 with the purpose of obtaining calibrated radar cross section (RCS) measurements of the coherent echoes of the lower ionosphere using the measured radar cross-section of incoherent scatter (IS) returns from F-region ionosphere and IS theory [Kudeki and Milla, 2011; Milla and Kudeki, 2011].The present study focuses on the effects of six solar flare events observed to cause significant changes in the mesosphere and the thermosphere. The largest event in terms of solar X-ray flux intensity was an X17.1 (peak of 17.1 × 10−4 W/m2) solar flare that occurred at approximately local noon on September 07, 2005. The second largest event was an X6.6 (peak of 6.6 × 10−4 W/m2) solar flare around 13:54 LT on December 06, 2006. The next event was an X5.5 (peak of 5.5 × 10−4 W/m2) solar flare around 16:00 LT on September 08, 2005. The next event was an M3.5 (peak of 0.35 × 10−4 W/m2) solar flare around 15:15 LT on December 06, 2006. The final two events were both M2.1 (peak of 0.21×10−4 W/m2) solar flares and occurred at 12:00 and 15:30 LT on September 08, 2005. During these events we observed an enhancement of D-region radar backscatter while F-region IS echoes were suppressed due to D-region absorption. Also, the equatorial electrojet (EEJ) radar backscatter was suppressed. Radar echoes from 150 km region were observed throughout the events but showed an abrupt initial drop in altitude by about 10 to 20 km followed by a slow recovery of 1 to 2 hours. Finally, in the case of the X17.1 and the X6.6 solar flares, 50 MHz solar radio emissions of type III and V were detected.