EFFECTS OF REFRACTION ON PHOTOCHEMICAL CALCULATIONS

A general method for the calculation of refracted ray paths through th e atmosphere is developed and adapted for photochemical modeling appli cations. The adapted method is then used to study the effect of refrac tion on the twilight radiation field and stratospheric photochemistry. We show that refraction has the effect of increasing the amount of so lar flux available for photodissociation in the atmosphere. This is ca used by both the reduction of the optical path of the direct solar bea m and a significant lengthening of the sunlit day. It is also shown th at for polar conditions, concentrations of O(P-3), NO3, and NO are sig nificantly affected by refraction.