5:15 PM - 7:15 PM
[PEM10-P22] Statistical study of the relationship between NO variability and magnetospheric activities/energetic particles based on mm-wave observations at Syowa Station
Keywords:Energetic particle precipitation, Atmospheric minor constituent, Polar region, ground based millimeter wave observation
Energetic particle precipitation (EPP) onto the polar regions induced by the solar activity ionizes atmospheric molecules, and the subsequent ion chemistry produces NOx and HOx, leading to depletion of ozone.
We started millimeter-wave spectroscopic observation of nitric oxide (NO) at Syowa Station in 2012 to clarify the atmospheric response to the energetic particle precipitation and have been observing six NO hyperfine structure lines simultaneously since July 2022 by using new multi-frequency millimeter-wave spectrometer. The results of the comparison of temporal variations of NO column densities and geomagnetic storms for the period from July 2022 to the end of 2023 were reported at the SGEPSS 2024 fall meeting.
Throughout the above period, there were 35 magnetic storms with Dst index more than -50 nT, and the NO column density increased in 24 of them, corresponding to 68%. A linear correlation between the amounts of the NO increment and Dst indices or electron flux above 40 keV was examined. The correlation coefficients were 0.58 and 0.61, respectively, indicating a weak correlation but no clear strong correlation as expected. The increment value in NO is defined as the difference between the minimum value of NO column density within two days before the magnetic storm and the maximum value within half a day before and two days after the magnetic storm. The electron flux values were averaged every 3 hours using 0-degree telescope data of POES/METOP satellite, selected using Syowa Station L-value (5.47 < L < 6.49) and MLT (< ±1.5h). In the presentation, we will report further statistical comparisons between the amount of NO increase and the physical quantities of magnetospheric activities and energetic particles, including data until December 2024, which will be brought back by Shirase in March.
We started millimeter-wave spectroscopic observation of nitric oxide (NO) at Syowa Station in 2012 to clarify the atmospheric response to the energetic particle precipitation and have been observing six NO hyperfine structure lines simultaneously since July 2022 by using new multi-frequency millimeter-wave spectrometer. The results of the comparison of temporal variations of NO column densities and geomagnetic storms for the period from July 2022 to the end of 2023 were reported at the SGEPSS 2024 fall meeting.
Throughout the above period, there were 35 magnetic storms with Dst index more than -50 nT, and the NO column density increased in 24 of them, corresponding to 68%. A linear correlation between the amounts of the NO increment and Dst indices or electron flux above 40 keV was examined. The correlation coefficients were 0.58 and 0.61, respectively, indicating a weak correlation but no clear strong correlation as expected. The increment value in NO is defined as the difference between the minimum value of NO column density within two days before the magnetic storm and the maximum value within half a day before and two days after the magnetic storm. The electron flux values were averaged every 3 hours using 0-degree telescope data of POES/METOP satellite, selected using Syowa Station L-value (5.47 < L < 6.49) and MLT (< ±1.5h). In the presentation, we will report further statistical comparisons between the amount of NO increase and the physical quantities of magnetospheric activities and energetic particles, including data until December 2024, which will be brought back by Shirase in March.