The global lightning-induced nitrogen oxides source

Introduction Conclusions References Tables Figures ◭ ◮ ◭ ◮ Back Close Full Screen / Esc Abstract Introduction Conclusions References Tables Figures ◭ ◮ ◭ ◮ Back Close Full Screen / Esc Abstract The knowledge of the lightning-induced nitrogen oxides (LNO x) source is important for understanding and predicting the nitrogen oxides and ozone distributions in the tro-posphere and their trends, the oxidising capacity of the atmosphere, and the lifetime of trace gases destroyed by reactions with OH. This knowledge is further required 5 for the assessment of other important NO x sources, in particular from aviation, the stratosphere, and from surface sources, and for understanding the possible feedback between climate changes and lightning. This paper reviews more then 3 decades of research. The review includes laboratory studies as well as surface, airborne and satellite-based observations of lightning and of NO x and related species in the atmo-10 sphere. Relevant data available from measurements in regions with strong LNO x influence are identified, including recent observations at midlatitudes and over tropical continents where most lightning occurs. Various methods to model LNO x at cloud scales or globally are described. Previous estimates are re-evaluated using the global annual mean flash frequency of 44±5 s −1 reported from OTD satellite data. From the review, 15 mainly of airborne measurements near thunderstorms and cloud-resolving models, we conclude that a " typical " thunderstorm flash produces 15 (2–40)×10 25 NO molecules per flash, equivalent to 250 mol NO x or 3.5 kg of N mass per flash with uncertainty factor from 0.13 to 2.7. Mainly as a result of previous global model studies for various LNO x parameterisations tested with related observations, the best estimate of the 20 annual global LNO x nitrogen mass source and its uncertainty range is (5±3) Tg a −1 in this study. An accuracy of order 1 Tg a −1 or 20%, as necessary in particular for understanding tropical tropospheric chemistry, is still a challenging goal.