MONTE-CARLO STUDIES OF THE RESONANCE FLUORESCENCE TECHNIQUE FOR ATMOSPHERIC ATOMIC OXYGEN MEASUREMENTS

The resonance fluorescence of the O (P-3-S-3) triplet has been used ex tensively for rocket-borne measurements of atomic oxygen in the mesosp here and lower thermosphere. The accuracy and compatibility of differe nt experimental configurations are however still a subject of controve rsy. In order to better quantify the measurements, we have developed a 3-dimensional Monte Carlo model which simulates the radiative transfe r inherent to atom detection by means of resonance lamps. Angle-depend ent partial frequency redistribution describes the fluorescence proces s, natural broadening becoming significant when the line center optica l thickness exceeds 10. Applying the model to a recently flown rocket instrument, a strong temperature dependence and nonlinear relations be tween atomic oxygen abundance and fluorescence signal are found at den sities above 5.10(10) cm(-3). Above 1.0(12) cm(-3), the signal gradual ly saturates and useful measurements cannot be obtained. The spatial d istribution of the scattering events and effects of the payload motion are analyzed. A discussion of the results is applied to different cal ibration techniques fbr rocket instruments. (C) 1997 Elsevier Science Ltd.