Tropospheric distribution and variability of N(2)O: Evidence for strong tropical emissions

Measurements of atmospheric N₂O spanning altitudes from the surface to 14 km, and latitudes from 67°S to 85°N, show high concentrations in the tropics and subtropics, with strong maxima in the middle and upper troposphere. The pattern varies significantly over time scales of a few weeks. Global simulations do not accurately capture observed distributions with latitude, altitude, or time. Inversion results indicate strong, episodic inputs of nitrous oxide from tropical regions (as large as 1 Tg N-N₂O over 9 weeks) are necessary to produce observed vertical and latitudinal distributions. These findings highlight strong tropical sources of N₂O with high temporal variability, and the necessity of using full vertical profile observations in deriving emissions from atmospheric measurements.