NO_x from lightning 2. Constraints from the global atmospheric electric circuit

The global atmospheric electric circuit can be used to constrain the total amount of NO_x produced by lightning (LNO_x). Since the global atmospheric electric circuit is regulated by global thunderstorm activity and, more specifically, global lightning currents, we use the global electric circuit to quantify and place limits on the total amount of energy available from lightning. Using a production rate of 10 × 10¹⁶ molecules NO/J, we have calculated the global LNO_x production on monthly, annual, and interannual timescales from 1983 to 1991. The 8-year mean production rate is found to be 13.2 Tg N/yr and agrees with the independent estimate derived in part 1 of this study (12.2 Tg N/yr), which is based on lightning physics and global lightning distributions. After considering the various uncertainties in these calculations, we conclude that the annual production rate of NO_x from lightning cannot be less than 5 nor more than 25 Tg N/yr.