Seasonal variations of the nocturnal mesospheric Na and Fe layers at 30°N
Seasonal variations of the nocturnal mesospheric Na and Fe layers at 30°N
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DOI：
10.1029/2008jd010344
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发表时间：
2009-01
期刊：
影响因子：
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通讯作者：
F. Yi;Changming Yu;Shaodong Zhang;X. Yue;Yujin He;Chunming Huang;Yunpeng Zhang;K. Huang
中科院分区：
文献类型：
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作者：
F. Yi;Changming Yu;Shaodong Zhang;X. Yue;Yujin He;Chunming Huang;Yunpeng Zhang;K. Huang
基于多年来的Na和Fe激光雷达测量，建立了中国武汉（30°N）夜间中层Na和Fe层的完整季节变化模式。Na和Fe层柱丰度都表现出强烈的年变化和温和的半年变化，在冬季达到最大值，在春末至中秋期间达到双最小值（注意，目前在5月中旬至7月中旬之间只有一个晚上的铁数据可用）。铁丰度的季节变化明显强于钠丰度的季节变化。Na层丰度的年平均值为~ 2.5 × 109 cm−2，而Fe层丰度的年平均值为~ 7.5 × 109 cm−2。Na和Fe质心高度以相似相位的半年振荡为主。Na的平均质心高度为~ 91.4 km， Fe的平均质心高度为~ 88.7 km。Na RMS宽度表现出强烈的半年振荡，冬季层略宽，而Fe宽度主要是年变化，冬季最大。Na层和Fe层的平均RMS宽度分别为4.5 km和4.1 km。将30°N观测到的Na和Fe层的季节特征与目前在其他纬度观测到的Na和Fe层进行了比较。与北纬40°和南极相比，其丰度的季节比值较小。它们的质心高度和均方根宽度的季节性变化也比所有其他纬度的对应值要小。年平均Na和Fe丰度约为40°N、18°N和南极的60-77%。这表明夜间Na和Fe层在30°N附近都有一个低丰度区域。根据北半球三个纬度的观测结果，年平均铁层宽度随纬度的增加而减小。
The complete seasonal variation patterns of the nocturnal mesospheric Na and Fe layers over Wuhan, China (30°N), have been established on the basis of several years of Na and Fe lidar measurements. Both the Na and Fe layer column abundances show strong annual variations as well as moderate semiannual variations with maxima in winter and double minima from late spring to midautumn (note that only one night of Fe data is presently available between mid‐May and mid‐July). The seasonal variation in the Fe abundance is evidently stronger than that of Na. The Na layer abundance has an annual mean of ∼2.5 × 109 cm−2, while this value for Fe is ∼7.5 × 109 cm−2. The Na and Fe centroid heights are dominated by semiannual oscillations with similar phases. The mean centroid heights are ∼91.4 km for Na and ∼88.7 km for Fe. The Na RMS width exhibits a strong semiannual oscillation with the layer slightly broader in winter, whereas the Fe width varies principally annually with a maximum in winter. The mean RMS widths of the Na and Fe layers are 4.5 and 4.1 km, respectively. The seasonal characteristics of the Na and Fe layers observed at 30°N have been compared with those currently available at other latitudes. The seasonal ratios of their abundances are smaller compared with 40°N and the South Pole. Their centroid heights and RMS widths also show less seasonal variations than the counterparts at all other latitudes. The annual mean Na and Fe abundances are about 60–77% of the counterparts at 40°N, 18°N, and the South Pole. This suggests that both the nocturnal Na and Fe layers have a low‐abundance region around 30°N. On the basis of the results observed at the three latitudes in the Northern Hemisphere, the annual mean Fe layer width decreases with increasing latitude.