EFFECT OF LIGHTNING ON THE CONCENTRATION OF ODD NITROGEN SPECIES IN THE LOWER STRATOSPHERE - AN UPDATE

Revised model estimates of the effect of lightning on the lower strato spheric NO(y) are presented. Several changes in the Atmospheric and En vironmental Research Incorporated model were made since the last evalu ation of the impact of lightning. Improvements were made in the model circulation and location of tropopause in the tropics, which is now ca lculated from the National Meteorological Center temperature data. Cha nges in model circulation reduced the mass flux from the troposphere t o the tropical stratosphere. The calculated mass fluxes are found to a gree better with some recent estimates. The circulation changes also r educed the advective mass flux from the tropical lower stratosphere to the midlatitudes. The change in circulation and the change in the tro popause height lead to increases in the calculated concentration of N2 O, O3 and NO(y) in the tropical lower stratosphere. The effect of ligh tning is to increase the calculated concentration of NO(y) around 64 m bar by a factor of 2, compared to a factor of 10 enhancement in the pr evious calculations. Comparison with the Stratosphere Troposphere Exch ange Project 1987 data indicates that the inclusion of a lightning sou rce brings the model results in closer agreement with the observations .