An attempt to identify the obscured paths of water cluster ions build-up in the D-region

A comparison of rocket-borne mass spectrometric measurements of the quiet daytime D-region positive ion concentrations above 75 km and the hypothesized detailed positive ion chemistry of the region is undertaken. Fast reactions analogous to the conversion of NO(+) to NO(+).H2O are needed to account for the observed concentrations of NO(+).(H2O)2 and NO(+).(H2O)3. Furthermore, a fast reaction converting O2(+) to O2(+).H2O is needed. A reaction route is also proposed to explain the distributions of hydronium ions.