Simultaneous, in situ measurements of OH, HO sub(2), O sub(3), and H sub(2)O: A test of modeled stratospheric HO sub(x) chemistry

Simultaneous, in situ measurements of OH, HO sub(2), H sub(2)O, and O sub(3) from 37-23 km are reported. The partitioning between OH and HO sub(2) and the total HO sub(x) concentration are compared with expected steady-state values. The ratio of HO sub(2) to OH varies from less than 2 at 36 km to more than 3 at 25 km; in the lower stratosphere this ratio is nearly a factor of two less than predicted. The data are used to calculate HO sub(x) production and loss rates. The measured HO sub(x) mixing ratio is consistent with production dominated by the reaction of O( super(1)D) with H sub(2)O, and loss controlled by NO sub(y) below 28 km and HO sub(x) above 30 km. The steady-state concentration of H sub(2)O sub(2) is inferred from the measured HO sub(2) concentration and calculated photolysis rate. The maximum H sub(2)O sub(2) mixing ratio (at 33 km) is predicted to be less than 0.2 ppb.