Impact of Lightning and Convection on Reactive Nitrogen in the Tropical Free Troposphere
Impact of Lightning and Convection on Reactive Nitrogen in the Tropical Free Troposphere
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DOI：
10.1029/97jd02073
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发表时间：
1997-12
影响因子：
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通讯作者：
S. Kawakami;Y. Kondo;M. Koike;H. Nakajima;G. Gregory;G. Sachse;R. Newell;E. Browell;D. Blake;José María Rodríguez;J. Merrill
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文献类型：
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作者：
S. Kawakami;Y. Kondo;M. Koike;H. Nakajima;G. Gregory;G. Sachse;R. Newell;E. Browell;D. Blake;José María Rodríguez;J. Merrill
1994年2月，DC-8飞机在西太平洋探测任务B（PEM-West B）期间，在30°N和10°S之间获得了8.9-12 km处NO、NOy、O3、CO、CH 3 I和H2O混合比的垂直分布。在3天内的两次飞行中，在1°N-14°N的9.5-12公里处观察到非常低的NOy混合比，中值为51万亿分之一体积（pptv）。一个非常低的中位数O3混合比为19十亿分之一的体积（ppb）和高混合比的H2O和CH 3 I同时观察到，这表明低NOy值可能是由于对流输送空气从热带海洋边界层到这个高度。中位NOy/O3比是一个因素的2小于在热带海洋边界层的空气质量可能表明的可能性，在对流输送过程中的HNO 3的异质去除进一步降低NOy水平。除9.5 ~ 12 km外，1°N下4 ~ 12 km的NOy和O_3值较低。200和1000 hPa辐散风场和红外云图显示，新几内亚岛东北部有大尺度对流（>1000 km × 1000 km），其中心位于0°S和150°E附近，是热带辐合带和南太平洋辐合带系统对流活动的一部分。这种类型的大尺度对流可以输送空气与低水平的NOy和O3的对流层中上部在热带地区的广泛区域。另一方面，在4°S和10°S之间的9.5 km处观察到50-200 pptv的NO混合比和0.4-0.6的高NOx/NOy比。高的H2O混合比为600-1200百万分之一的体积（ppmv）和低的CO混合比为65 ppbv的空气质量中观察到的高NO值可能是由于NO生产的闪电。卫星观测显示，在飞机测量之前的3天里，新几内亚岛上空的闪电相对频繁。这些结果被认为是一致的想法，在一般情况下，海洋对流是不伴随着闪电活动，而在陆地对流。由于这些过程的影响范围很大，低NOy空气的对流输送和闪电产生的NO应该在控制赤道地区活性氮的丰度方面发挥关键作用。
Latitudinal distributions of NO, NOy, O3, CO, CH3I, and H2O mixing ratios at 8.9–12 km were obtained between 30°N and 10°S by DC-8 aircraft measurements made in February 1994 during Pacific Exploratory Mission-West B (PEM-West B). Very low NOy mixing ratios with a median value of 51 parts per trillion by volume (pptv) were observed at 9.5–12 km at 1°N–14°N during two flights made within 3 days. A very low median O3 mixing ratio of 19 parts per billion by volume (ppbv) and high mixing ratios of H2O and CH3I were simultaneously observed, suggesting that the low NOy values were probably due to the convective transport of air from the tropical marine boundary layer to this altitude. The median NOy/O3 ratio being a factor of 2 smaller than in the air masses in the tropical marine boundary layer might suggest the possibility that the heterogeneous removal of HNO3 during convective transport further reduced NOy levels. In addition to the measurements between 9.5 and 12 km, low values of NOy and O3 were observed between 4 and 12 km at 1°N. Divergent wind fields at 200 and 1000 hPa and infrared (IR) cloud images show that there was large scale convection (>1000 km × 1000 km) in the northeast of New Guinea Island centered around 0°S and 150°E as part of systematic convective activity of the Intertropical Convergence Zone (ITCZ) and the South Pacific Convergence Zone (SPCZ). This type of large scale convection could have transported air with low levels of NOy and O3 to the middle and upper troposphere over a wide area in the tropics. On the other hand, NO mixing ratios of 50–200 pptv and high NOx/NOy ratios of 0.4–0.6 were observed at 9.5 km between 4°S and 10°S. High H2O mixing ratios of 600–1200 parts per million by volume (ppmv) and low CO mixing ratios of 65 ppbv observed in the air mass indicated that the high NO values were probably due to NO production by lightning. Satellite observations showed relatively frequent lightning flashes over the New Guinea Island for 3 days prior to the aircraft measurements. These results are considered to be consistent with the idea that, in general, marine convection is not accompanied by lightning activity, whereas convection over land is. Because of the large areal extent of the influences from these processes, the convective transport of low NOy air and NO production by lightning should play critical roles in controlling the abundance of reactive nitrogen in the equatorial region.