The lifetime of the OH radical in comets at 1 AU

It has been shown that the photochemical lifetime of OH in comets is a function of the comet's radial velocity. The calculated lifetime at 1 AU can vary between 6.9 × 10⁴ to 2.1 × 10⁵ sec for radial velocities that vary from ?58 to +59 km/sec. A comparison between the scale lengths observed for three comets and those calculated based upon the theoretical lifetime has been made. This comparison shows that in two of the comets the lifetime derived from the scale lengths is a factor of 1.7 larger than the theoretical lifetime. Suggestions are made about the origin of this discrepancy.