Interannual variability in tropospheric nitrous oxide

Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. [1] Observations 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.