A global atmospheric model of meteoric iron
A global atmospheric model of meteoric iron
复制标题
DOI：
10.1002/jgrd.50708
复制
发表时间：
2013-08
期刊：
影响因子：
--
通讯作者：
W. Feng;D. Marsh;M. Chipperfield;D. Janches;J. Höffner;F. Yi;J. Plane
中科院分区：
文献类型：
--
作者：
W. Feng;D. Marsh;M. Chipperfield;D. Janches;J. Höffner;F. Yi;J. Plane
第一个大气中陨铁的全球模型（WACCM-Fe）是通过结合三个组成部分开发的：全大气群落气候模型（WACCM），描述中间层和低热层（MLT）中铁的中性和离子分子化学，以及对大气中陨铁成分注入的处理。铁化学处理七个中性和四个离子化的含铁物种与30个中性和离子-分子反应。流星输入函数（MIF），它描述了作为高度，纬度和天的函数的Fe的注入，是预先计算从一个天文模型耦合到一个化学流星消融模型（CABMOD）。这个新开发的WACCM-Fe模型已经针对一些可用的地基激光雷达观测进行了评估，并在模拟中间层原子Fe层方面表现良好。该模式再现了Fe层峰值附近温度与Fe浓度的强正相关关系和100 km附近的大相关关系。日潮在中层有显著的影响，模型也很好地捕捉到了观测到的季节变化。然而，与有限的火箭载质谱仪数据相比，该模型高估了Fe+的峰值浓度，尽管通过调整Fe分子离子与电子解离复合的速率系数可以获得离子层底面的良好一致性。在一维模型中使用相同化学成分的敏感性实验来突出反应速率系数中剩余的显著不确定性，并探索总Fe丰度对MIF和垂直传输速率的依赖性。
The first global model of meteoric iron in the atmosphere (WACCM‐Fe) has been developed by combining three components: the Whole Atmosphere Community Climate Model (WACCM), a description of the neutral and ion‐molecule chemistry of iron in the mesosphere and lower thermosphere (MLT), and a treatment of the injection of meteoric constituents into the atmosphere. The iron chemistry treats seven neutral and four ionized iron containing species with 30 neutral and ion‐molecule reactions. The meteoric input function (MIF), which describes the injection of Fe as a function of height, latitude, and day, is precalculated from an astronomical model coupled to a chemical meteoric ablation model (CABMOD). This newly developed WACCM‐Fe model has been evaluated against a number of available ground‐based lidar observations and performs well in simulating the mesospheric atomic Fe layer. The model reproduces the strong positive correlation of temperature and Fe density around the Fe layer peak and the large anticorrelation around 100 km. The diurnal tide has a significant effect in the middle of the layer, and the model also captures well the observed seasonal variations. However, the model overestimates the peak Fe+concentration compared with the limited rocket‐borne mass spectrometer data available, although good agreement on the ion layer underside can be obtained by adjusting the rate coefficients for dissociative recombination of Fe‐molecular ions with electrons. Sensitivity experiments with the same chemistry in a 1‐D model are used to highlight significant remaining uncertainties in reaction rate coefficients, and to explore the dependence of the total Fe abundance on the MIF and rate of vertical transport.