Global reactive nitrogen deposition from lightning NO_x

We present results of the deposition of nitrogen compounds formed from lightning (LNO_x) using the global chemical transport Model of Atmospheric Transport and Chemistry-Max Planck Institute for Chemistry version. The model indicates an approximately equal deposition of LNO_x in both terrestrial and oceanic ecosystems, primarily in the tropics and midlatitudes open ocean, despite much higher intensities of lightning flashes above landmasses. The highest values of deposition are due to wet convective deposition, with highest values concentrated in the tropical continents. Nonconvective wet deposition, associated with large-scale weather patterns, occurs over large areas of the ocean amid lower values per square meter, manifesting the long-range transport of NO_y, including long-lived species such as HNO₃ at high altitudes and PAN. Dry deposition is concentrated primarily above landmasses, yet oceanic deposition over wide areas is still observed. Combined together, the total LNO_x deposition exhibits maximal influx values over land, whereas oceanic deposition over wider areas renders the integrated deposition over both ecosystems almost identical. Peaks of terrestrial deposition values (located in Africa, South America, and Asia) show seasonal variability by meridionally penetrating the northern or southern midlatitude following the corresponding summer hemisphere, in accordance with the migration of LNO_x production sites. On land, wet and dry deposition rates are more or less equal with a small bias toward wet deposition, whereas above the ocean, wet deposition is markedly higher because of a small water uptake efficiency and relatively small surface roughness. Further work of modeling additional species and obtaining more information on different compounds is required.