Sensitive response of atmospheric oxidative capacity to the uncertainty
in the emissions of nitric oxide (NO) from soils in Amazonia
Abstract
Soils are a major source of nitrogen oxides, which in the atmosphere
help govern its oxidative capacity. Thus the response of soil nitric
oxide (NO) emissions to forcings such as warming or forest loss has a
meaningful impact on global atmospheric chemistry. We find that the soil
emission rate of NO in Amazonia from a common inventory is biased low by
at least an order of magnitude in comparison to tower-based
observations. Accounting for this regional bias decreases the modeled
global methane lifetime by 1.4% to 2.6%. In comparison, a fully
deforested Amazonia, representing a 37% decrease in global emissions of
isoprene, decreases methane lifetime by at most 4.6%, highlighting the
sensitive response of oxidation rates to changes in emissions of NO
compared to those of terpenes. Our results demonstrate that improving
our understanding of soil NO emissions will yield a more accurate
representation of atmospheric oxidative capacity.