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 $$\sim 95 \,\hbox {km}$$ ∼ 95 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.

中文翻译：

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在南极绍瓦观测到的 Na 层与 CNA 变化之间的关系

我们对 2000 年至 2002 年在南极绍瓦获得的同步 Na 密度数据和宇宙噪声吸收 (CNA) 数据之间的关系进行了统计数据分析，CNA 数据是高能粒子降水的指标。发现当 CNA 较大时，Na 层顶部（高于 $$\sim 95 \,\hbox {km}$$ ∼ 95 km 高度）周围的 Na 密度趋于较小。从黄昏到黎明时分，Na 密度响应，即Na 密度降低或Na 损失，随着磁本地时间(MLT) 的增加而增加，而CNA 响应，即CNA 增加，也随着MLT 的增加而增加。因此，Na 密度和 CNA 变化之间存在明显的负相关。这些结果表明，Na 层顶部周围的 Na 损失是由高能粒子沉淀引起的，