Using cloud ice flux to parametrise large-scale lightning
Using cloud ice flux to parametrise large-scale lightning
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DOI：
10.5194/acp-14-12665-2014
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发表时间：
2014-01-01
影响因子：
6.3
通讯作者：
Blyth, A. M.
中科院分区：
文献类型：
--
作者：
Finney, D. L.;Doherty, R. M.;Blyth, A. M.
闪电是氮氧化物的重要天然来源，尤其是在对流层中上部。因此，在化学输送和耦合化学气候模式中，闪电的模拟是必不可少的。使用ERA-Interim气象再分析数据，我们比较了使用几个现有的闪电参数化产生的闪电密度分布，以及在440 hPa向上的云冰通量的基础上开发的新参数化。冰通量的使用与雷暴的非感应充电机制形成了联系。闪电密度的空间和时间分布进行了比较热带和亚热带观测2007-2011年从闪电成像传感器（LIS）的热带降雨测量使命（TRMM）卫星。基于云顶高度的常用闪电参数化有很大的偏差，但推导出的年总闪电密度与LIS观测比其他现有的参数化有更好的空间相关性。不同方案模拟的闪光密度的比较表明，云顶高度参数化有更多的情况下，中等闪光密度和更少的低和高的极端相比，其他parametrisations。文献中的其他研究表明，云顶高度参数化的这一特征与某些地区的闪电观测相反。我们的新的冰通量参数化显示出明显的改善，所有现有的参数化与较低的均方根误差（RMSE）和更好的空间相关性与观测的年度总分布，季节和年际变化。最大的改进与新的参数化是一个更现实的代表性的纬向分布与热带和亚热带闪电之间的估计更好的平衡。新的参数化是适当的测试化学运输和化学气候模式，使用闪电参数化。
Lightning is an important natural source of nitrogen oxide especially in the middle and upper troposphere. Hence, it is essential to represent lightning in chemistry transport and coupled chemistry climate models. Using ERA-Interim meteorological reanalysis data we compare the lightning flash density distributions produced using several existing lightning parametrisations, as well as a new parametrisation developed on the basis of upward cloud ice flux at 440 hPa. The use of ice flux forms a link to the non-inductive charging mechanism of thunderstorms. Spatial and temporal distributions of lightning flash density are compared to tropical and subtropical observations for 2007-2011 from the Lightning Imaging Sensor (LIS) on the Tropical Rainfall Measuring Mission (TRMM) satellite. The well-used lightning flash parametrisation based on cloud-top height has large biases but the derived annual total flash density has a better spatial correlation with the LIS observations than other existing parametrisations. A comparison of flash density simulated by the different schemes shows that the cloud-top height parametrisation has many more instances of moderate flash densities and fewer low and high extremes compared to the other parametrisations. Other studies in the literature have shown that this feature of the cloud-top height parametrisation is in contrast to lightning observations over certain regions. Our new ice flux parametrisation shows a clear improvement over all the existing parametrisations with lower root mean square errors (RMSEs) and better spatial correlations with the observations for distributions of annual total, and seasonal and interannual variations. The greatest improvement with the new parametrisation is a more realistic representation of the zonal distribution with a better balance between tropical and subtropical lightning flash estimates. The new parametrisation is appropriate for testing in chemistry transport and chemistry climate models that use a lightning parametrisation.