Relationship between Na layer and CNA variations observed at Syowa, Antarctic

T T Tsuda,R Tozu,M K Ejiri,T D Kawahara,Y -M Tanaka,T Nakamura,T Nishiyama,K Takizawa

doi:10.1186/s40623-020-01335-7

Abstract

We have performed a statistical data analysis on relationship between simultaneous Na density data and cosmic noise absorption (CNA) data, which is an indicator for energetic particle precipitation, obtained at Syowa, Antarctic in 2000–2002. It is found that the Na densities around the topside of Na layers (above sim 95 ,hbox {km} height) tended to be smaller when the CNA was larger. The amounts of Na density responses, i.e., Na density decrease or Na loss, were increasing with magnetic local time (MLT) from dusk hours to dawn hours, and those of CNA responses, i.e., CNA increase, were also increasing with MLT. Thus, there were clear negative correlations between the Na density and CNA variations. These results indicate that the Na loss around the topside of Na layer would be induced by the energetic particle precipitation, and its effect would be more severe in dawn hours.

Highlights

The sodium (Na) layer around 80–110-km heights is one of the metal layers existing in the Earth’s upper atmosphere, and has been widely used as a valuable observation target to study the upper atmospheric science using the lidar technique
Event-based investigations were performed, and those reported conflicting results and/or suggestions regarding the response in the Na density to auroral activity
Tsuda et al (2017) made a statistical investigation using Odin/Optical Spectrograph and Infrared Imager System (OSIRIS) data together with AE index, and it showed a significant decrease in the Na density above ∼ 95 km height during the geomagnetically active periods

Summary

Introduction

The sodium (Na) layer around 80–110-km heights is one of the metal layers existing in the Earth’s upper atmosphere, and has been widely used as a valuable observation target to study the upper atmospheric science using the lidar technique (cf. Chu and Papen 2005, and references therein). At ∼ 100 km height, the median Na densities during the active days were a bit smaller than those during the quiet days.

Results

Conclusion