# Do NO2 and O3 titrate each other out in the atmosphere?

Here is a plot of the vertical column densities of NO2 and O3 from an ultraviolet-visible spectrometer in Fairbanks, Alaska. It is interesting to see that when NO2 dips, O3 rises, and vice versa. Also, because the scale of both the graphs is so different, I cannot plot them together, which makes it difficult to see if the dips in both the plots is occurring simultaneously. This is important to verify the fact that is the instrument compromised by any kind of artefact or not. I was thinking of doing a dy/dx (where y=NO2 and x=O3) to see if the sign is the same, meaning that both the measurements are following the same pattern. Otherwise, the general trend of both the measurements is supposed to be opposite. Is this a good way to check my hypothesis?

• Both of them are strong oxidisers, so I doubt they react with each other. There might be a separate reason for it. – Gimelist May 28 '18 at 9:47
• In fact, they do. NO2 + O3 -> NO3 + O2; NO2 + NO3 <-> N2O5. This reaction was published in the following paper: pubs.acs.org/doi/pdf/10.1021/j100907a003 – Sujai Banerji May 28 '18 at 9:54
• You have the cycle NO + O -> NO_2 and NO_2 + h \nu -> NO + O. Whereas the O comes from O_3. Thus, if you have a lot of NO_2 and solar radiation (h \nu), you can expect to get a lot of ozone. Or the other way around: a lot of ozone plus NO leads to higher levels of NO_2. – daniel.heydebreck May 28 '18 at 14:00
• www-personal.umich.edu/~sillman/ozone.htm#OZO1.2.1 may be of use – farrenthorpe May 28 '18 at 18:25
• The NO-to-NO2-ratio, the total amount of NO+NO2, and the amount of solar radiation are important factors, which govern this process. If you have low NO+NO2 concentrations and their emissions are low (anthropogenic combustion) then it won't interact much with you O3. – daniel.heydebreck May 30 '18 at 7:33