Model studies of short‐term variations induced in trace gases by particle precipitation in the mesosphere and lower thermosphere
Model studies of short‐term variations induced in trace gases by particle precipitation in the mesosphere and lower thermosphere
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DOI：
10.1002/2015ja022291
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发表时间：
2016-10
期刊：
影响因子：
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通讯作者：
T. Fytterer;S. Bender;U. Berger;H. Nieder;M. Sinnhuber;J. Wissing
中科院分区：
文献类型：
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作者：
T. Fytterer;S. Bender;U. Berger;H. Nieder;M. Sinnhuber;J. Wissing
利用三维全球化学和输运模式(3dCTM)对2002年1月至2010年5月60~133公里范围内的NO、OH和O_3进行了研究。分析了它们的白天和夜间平均纬向平均值(地磁纬度55°-75°)与粒子降水有关的短期变化。相应的电离率是从三维大气电离模块Osnabrück(AIMOS)推导出来的，该模块基于粒子通量测量。利用叠加历元分析研究了痕量气体相对于背景的变化。与颗粒物降水有关的27天特征在NO中被发现，而在冬季只在OH和O_3中被发现。与11年太阳周期相关的变化的太阳光谱导致这一信号的变化高达10%，而主要模式是保守的。已发表的观测显示了一个清晰的27天信号，在北半球冬季除臭氧外，在70公里的高度上与模型结果定性一致。在痕量气体变化的大小方面也存在进一步的差异，这主要归因于不同的痕量气体背景和背景大气的动力学变化。3DCTM在冬季高估了OH的绝对值变化，而臭氧的变化则相反。这些差异可能源于AIMOS中未知的偏移量、不正确的化学反应速率、不同的水和臭氧背景以及模型动力学。但在南半球冬季，定性地捕捉到了它们之间的非线性关系和响应最大的高度。
The 3‐D global chemistry and transport model (3dCTM) was used to investigate NO, OH, and O3 from January 2002 to May 2010 between 60 km and 133 km. Their daytime and nighttime mean zonal means (55°–75° geomagnetic latitude) were analyzed with respect to short‐term variations associated with particle precipitation. The corresponding ionization rates were derived from the 3‐D atmospheric ionization module Osnabrück (AIMOS), which is based on particle flux measurements. The trace gas variations with respect to their background were investigated by using a superposed epoch analysis. The 27 day signature associated with particle precipitation is found in NO, while it is only indicated in OH and O3 during winter. A varying solar spectrum associated with the 11 year solar cycle causes modifications of this signal up to 10%, while the main patterns are conserved. Published observations show a clear 27 day signal, qualitatively agreeing with the model results at altitudes >70 km except for O3 in Northern Hemisphere winter. Further differences occur with respect to the magnitude of the trace gas variations, primarily attributed to the different trace gas background and dynamical variations of the background atmosphere. Absolute OH variations are overestimated by the 3dCTM during winter, while the opposite is true for O3. These differences might originate from an unknown offset in AIMOS, incorrect chemical reaction rates, a different background of H2O and O3, and the model dynamics. However, their nonlinear relationship and their altitude of largest response are qualitatively captured in Southern Hemisphere winter.