Relationship between Lightning Activity and Tropospheric Nitrogen Dioxide and the Estimation of Lightning-produced Nitrogen Oxides over China

To better understand the relationship between lightning activity and nitrogen oxides （NOx） in the troposphere and to estimate lightning-produced NOx （LNOx） production in China more precisely, spatial and temporal distributions of vertical column densities of tropospheric nitrogen dioxide （NO2 VCDs） and lightning activity were analyzed using satellite measure- ments. The results showed that the spatial distribution of lightning activity is greater in the east than in the west of China, as with NO2 VCDs. However, the seasonal and annual variation between lightning and NO2 density show different trends in the east and west. The central Tibetan Plateau is sparsely populated without modem industry, and NO2 VCDs across the plateau are barely affected by anthropogenic sources. The plateau is an ideal area to study LNOx. By analyzing 15 years of satellite data from that region, it was found that lightning density is in strong agreement with annual, spatial and seasonal variations of NO2 VCDs, with a correlation coefficient of 0.79 from the linear fit. Combining Beirle＇s method and the linear fit equation, LNOx production in the Chinese interior was determined to be 0.07 （0.02-0.27） TgN yr-1 for 1997-2012, within the range of 0.016-0.384 TgN yr-1 from previous estimates.

青藏高原闪电与NO_2的分析及中国内陆地区LNO_x产量的估算

为了进一步认识闪电活动与对流层氮氧化物的关系及更准确地估算中国地区闪电产生的氮氧化物（LNOx）总量,选取人口稀疏,工业生产水平较低的青藏高原地区作为研究区域,基于LIS（Lightning Imaging Sensor）和GOME-2（The Global Ozone Monitoring Experiment-2）卫星探测仪资料,分析了青藏高原中部区域2009年1月至2012年2月闪电与对流层NO2垂直浓度（VCD）月均值资料的时空分布特性和相关性。在此基础上,结合Beirle et al.（2004）的LNOx估算方法,估算了中国内陆地区的LNOx产量。结果表明：青藏高原地区对流层NO2与闪电与在年际趋势、空间分布及季节变化上保持很好的一致性,闪电密度与NO2VCD的线性拟合相关系数为0.84,这表明青藏高原地区NOx受人为源影响小,是研究LNOx的理想区域。基于拟合结果,估算得到中国内陆地区LNOx的年均产量为0.15（0.03-0.38）Tg（N）a^-1。这一结论进一步缩小了以往研究中中国地区LNOx产量估算的不确定范围,有助于更清楚地认识闪电在中国气候变化中的重要作用。