The production of NOx by lightning over the contiguous United States has been evaluated by using combined ground-based and satellite lightning measurements. The lightning data from the National Lightning Detection Network (NLDN) over the period of 1995-1999, along with a ratio of intracloud (IC) to cloud-to-ground (CG) flashes derived in conjunction with satellite lightning measurements from the Optical Transient Detector (OTD), are analyzed to obtain the number of CG and IC flashes. The average annual lightning counts over the 5-year period are about 23 million for CG flashes and 55 million for IC flashes. The resulting lightning distributions are employed to calculate the production of NOx assuming a NO production rate of 6.7 x 10(26) molecules for each CG flash and 6.7 x 10(21) molecules for each IC flash. NOx production by lightning varies seasonally in accordance with the lightning distribution, with the maximum production occurring in the summer (June, July, and August) and in the Southeast. CG flashes produce more NOx than IC flashes despite fewer CG flashes by a factor of 2 or more. The geographical and seasonal production of NOx by lightning is compared to NOx emissions from other sources (i.e., from anthropogenic, soil, and biomass-burning emissions). The results indicate that regional emissions of NOx by lightning can be significant in the summertime and may play a critical role in ozone formation in the free troposphere. Our estimate of NOx emission by lightning over the United States would decrease by an order of magnitude if we use the production rates from a recent laboratory study [Wang et al., 1998] that are significantly lower than previous estimates. [References: 53]
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机译：已通过结合使用地面和卫星闪电测量技术评估了连续美国闪电产生的NOx。 1995年至1999年期间，来自国家闪电检测网络（NLDN）的闪电数据，以及根据光学暂态的卫星闪电测量结果得出的内部云（IC）与云对地（CG）闪光的比率分析检测器（OTD），以获得CG和IC闪烁的次数。五年内，CG闪光的年平均雷电计数约为2300万次，IC闪光的年雷电计数约为5500万次。假设每个CG闪光灯的NO生成率为6.7 x 10（26）分子，每个IC闪光灯的6.7 x 10（21）分子的NO生成速率，则使用所得的闪电分布来计算NOx的生成。闪电产生的NOx产量随闪电分布而季节性变化，最大产量发生在夏季（6月，7月和8月）和东南部。尽管CG闪光的数量减少了2倍或更多，但CG闪光比IC闪光产生的NOx更多。将闪电产生的NOx的地理和季节性生产与其他来源（即人为，土壤和燃烧生物质的排放）的NOx排放进行了比较。结果表明，在夏季，闪电引起的NOx区域排放可能很大，并且可能在自由对流层中的臭氧形成中发挥关键作用。如果我们使用最近的实验室研究[Wang et al。，1998]的生产率大大低于以前的估计，我们对美国闪电产生的NOx排放的估计将减少一个数量级。 [参考：53]
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