Quantification of lightning-induced nitrogen oxide emissions over Europe


In this study, the importance of lightning-generated NO over Europe in the year 2010 is assessed with the COSMO-CCLM - SMOKE-EU - CMAQ chemistry transport modeling system. Lightning data from TRMM satellite flash density data climatologies are taken and linearly fitted to convective precipitation climatologies. With the resulting linear model, lightning activity in 2010 is calculated based on the convective precipitation rate from model data. This approach combines the globally available satellite observations with the simplicity of linear convective rain parameterizations. It provides a new method for fitting lightning data for linear flash density parameterizations. Compared to other linear flash rate approaches or the very common cloud top height parameterization, the data for 2010 derived by the climatologies and actual 2010 precipitation data better matches the TRMM observation data. Lightning was found to be the second most important natural source after nitrogen monoxide emission from soil, with an annual average amount of 0.295 Tg N per year and an amount in 2010 of 0.278 Tg N. While it is less important for near-surface concentrations, it has a considerable effect on the nitrogen deposition in southern and eastern Europe and a large effect on the NO2 concentration in higher model layers. The effect in higher atmospheric layers over eastern Europe is 6 times larger than the effect of aircrafts on the air concentration of NO2 in the mid- and high altitudes. Comparisons with NO2 observations from the OMI satellite revealed that lightning NO emissions have an observable impact on the NO2 column density over Europe.
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