Interannual variability in tropospheric nitrous oxide

International audienceObservations of tropospheric N 2 O mixing ratio show significant variability on interannual timescales (0.2 ppb, 1 standard deviation). We found that interannual variability in N 2 O is weakly correlated with that in CFC-12 and SF 6 for the northern extratropics and more strongly correlated for the southern extratropics, suggesting that interannual variability in all these species is influenced by large-scale atmospheric circulation changes and, for SF 6 in particular, interhemispheric transport. N 2 O interannual variability was not, however, correlated with polar lower stratospheric temperature, which is used as a proxy for stratosphere-to-troposphere transport in the extratropics. This suggests that stratosphere-to-troposphere transport is not a dominant factor in year-to-year variations in N 2 O growth rate. Instead, we found strong correlations of N 2 O interannual variability with the Multivariate ENSO Index. The climate variables, precipitation, soil moisture, and temperature were also found to be significantly correlated with N 2 O interannual variability, suggesting that climate-driven changes in soil N 2 O flux may be important for variations in N 2 O growth rate