The terrestrial potassium layer (75–110 km) between 71°S and 54°N: Observations and modeling
The terrestrial potassium layer (75–110 km) between 71°S and 54°N: Observations and modeling
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DOI：
10.1029/1999ja900117
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发表时间：
1999-08
影响因子：
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通讯作者：
V. Eska;U. Zahn;J. Plane
中科院分区：
文献类型：
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作者：
V. Eska;U. Zahn;J. Plane
1996年3月至6月在德国研究船Polarstern上对夜间大气钾层进行了观测。在71°S和45°N之间获得了K密度分布。夜间平均峰值密度从赤道地区的140 cm−3到南极地区的10 cm−3不等，柱丰度从低纬度到高纬度从1.2 × 108 cm−2下降到1.3 × 107 cm−2。高峰密度和柱丰度也经常观察到零星的K层。正常（背景）K层的全球平均峰值高度为88.3 km。在北极星战役之后，继续在库隆斯博恩（北纬54度）进行观测。1996年7月和1997年1月期间观察到的夏季和冬季K层的形状有很大不同，但具有相似的峰值密度和柱丰度。一个一维模型的K层，其中包括大气沉降，垂直输送通过涡扩散，和一个完整的化学方案。如果冬季K层的沉降通量比夏季减少30%，则该模式能够非常满意地再现54°N处K层的季节变化。中纬度地区K与Na的比值约为1%，远低于这两种金属的绝对比值或宇宙比值（分别为0.8%或6%）。最有可能的原因是钾从流星体中蒸发的效率低于钠，这与非理想岩浆的热力学模型和水星外逸层的观测结果一致。最后，该模式在再现K层的纬度变化方面通常非常成功。
Observations of the nighttime atmospheric potassium layer were performed on the German research vessel Polarstern from March to June 1996. K density profiles were obtained between 71°S and 45°N. The nightly mean peak densities ranged from 140 cm−3 in the equatorial region to 10 cm−3 in the Antarctic, and the column abundances decreased from 1.2 × 108 to 1.3 × 107 cm−2 going from low to high latitudes. High peak densities and column abundances were also commonly observed together with sporadic K layers. The global mean peak height of the normal (background) K layer was found to be 88.3 km. After the Polarstern campaign, observations were continued at Kuhlungsborn (54°N). The summer and winter K layers, observed during July 1996 and January 1997, were quite different in shape but had similar peak densities and column abundances. A one-dimensional model of the K layer was developed which includes meteoric deposition, vertical transport through eddy diffusion, and a full chemical scheme. This model was able to reproduce very satisfactorily the seasonal behavior of the K layer at 54°N if the wintertime deposition flux of the metal was reduced by 30% compared to the summer. The midlatitude ratio of K to Na was about 1%, much less than either the chondritic or cosmic ratios of the two metals (≈8 or 6%, respectively). The most likely reason is that potassium vaporizes less efficiently from meteoroids than sodium, in agreement with a thermodynamic model of a nonideal chondritic magma and observations in the exosphere of Mercury. Finally, the model was generally very successful in reproducing the latitudinal variations in the K layer.