Three‐dimensional model simulations of SF6 with mesospheric chemistry
Three‐dimensional model simulations of SF6 with mesospheric chemistry
复制标题
SF6 中层化学三维模型模拟
DOI：
--
复制
发表时间：
2001
期刊：
影响因子：
--
通讯作者：
W. Kouker
中科院分区：
文献类型：
--
作者：
T. Reddmann;R. Ruhnke;W. Kouker
用卡尔斯鲁厄中大气模拟模式(KASIMA)进行了多年积分，利用10hpa以下的涡度和散度的气象分析，分析了简化的SF6中间层化学对估计空气平均年龄的影响，并比较了平流层观测到的SF6混合率分布与模式模拟的差异。化学降解包括SF6的电子附着和SF6-的后续反应，如光剥离和与臭氧的电荷转移。对反应速率常数和电子分布的几种组合进行了测试。对于惰性的SF6输运，发现与观测结果很好地一致。然而，当模式中计入中层损失时，极地冬季25公里以上的观测值有明显的偏差。没有反应的电子附着造成的化学损失再次产生了SF6，这与观测结果不符。根据假设的损耗机制和平流层中电子密度的值，SF6的大气寿命跨度为400到10000年。
Multiannual integrations with the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA) have been performed using meteorological analyses of vorticity and divergence up to 10 hPa to analyze the influence of a simplified SF 6 mesospheric chemistry on estimation of mean age of air and to compare profiles of SF 6 mixing ratios observed in the stratosphere with model simulations. The chemical degradation scheme includes electron attachment of SF 6 and subsequent reactions of SF 6 - , such as photodetachment and charge transfer with ozone. Several combinations of reaction rate constants and electron profiles have been tested. Good agreement with observations is found for inert SF 6 transport. However, when mesospheric loss is inclnded in the model, significant deviations are found for polar winter observations above 25 km. Chemical loss by electron attachment without reactions yielding SF 6 again is not compatible with observations. The atmospheric lifetime of SF 6 spans 400 to 10,000 years, depending on the assumed loss mechanism and the value for the electron density in the stratosphere.