Yienger, J. J., and H. Levy II, 1995: Empirical model of global soil-biogenic
NOx emissions. Journal of Geophysical
Research, 100(D6), 11,447-11,464.
Abstract: We construct a global, temperature and precipitation dependent,
empirical model of soil biogenic NOx emissions
using 6-hour general circulation model forcing. New features of this source
relative to the latest published ones by Dignon et al. [1992] and Muller
[1992] include synoptic-scale modeling of "pulsing" (the emissions
burst following the wetting of a dry soil), a biome dependent scheme to
estimate canopy recapture of NOx, and an
explicit linear dependence of emission on N fertilizer rate for agricultural
soils. Our best estimate for annual above-canopy emissions is 5.5 Tg N
(NOx) with a range of 3.3-7.7 Tg N. Globally,
the strongest emitters are agriculture, grasslands, and tropical rain forests,
accounting for 41%, 35%, and 16% of the annual budget, respectively. "Pulsing"
contributes 1.3 Tg N annually. In temperate regions, agriculture dominates
emission, and in tropical regions, grassland dominates. Canopy recapture
is significant, consuming, on average, possibly 50% of soil emissions.
In temperate regions, periodic temperature changes associated with synoptic-scale
distu;rbances can cause emission fluctuations of up to 20 ng N m-2
s-1, indicating a close correlation between
emission and warm weather events favorable to O3/smog
formation. By the year 2025, increasing use of nitrogen fertilizer may
raise total annual emissions to 6.9 Tg N with agriculture accounting for
more than 50% of the global source. Finally, biomass burning may add up
to an additional 0.6 Tg N globally by stimulating emissions for a short
period after the burn.