Influence of global lightning source of NOx on atmospheric ozone and odd nitrogen

Reactive nitrogen oxides (NOx = NO + NO2) play a key role in the photochemi cal processes that form the tropospheric and stratospheric ozone layer. Dep ending on their content in different atmospheric parts, they either destroy ozone or facilitate its formation. The global lightning source of NOx (NOx -GLS) is a major source of tropospheric nitrogen oxides, but its strength e stimates have a high degree of uncertainty (2-200 Tg N/yr). In this study, the effect of NOx-GLS on the atmospheric odd nitrogen (NO,I) and ozone cont ents is examined by using a zonally averaged interactive model of radiative , dynamic, and photochemical processes in the troposphere and stratosphere. The sensitivity of the total ozone content to the NOx-GLS strength is anal yzed, and the model total ozone content is compared to the TOMS data over 1 979-1994. The introduction of the lightning source of nitrogen oxides into the model led to a much closer agreement between the computed total ozone c ontents and the observed data, especially in the tropical latitudes. The re lative error of the computed ozone content against the measurements decreas es as the NOx-GLS strength increases and reaches a minimum when the global lightning source strength comprises 20 Tg N/yr. It is proposed to view this strength value as a model estimate for the global formation of atmospheric nitrogen dioxides caused by lightning.