The effect of collisions with nitrogen on absorption by oxygen in the a-band using cavity ring-down spectroscopy

International audience; This paper reports on the effect of collisions between nitrogen and oxygen on absorption in the A-band near 760 nm under atmospheric conditions relevant for satellite retrieval studies. We use pulsed laser cavity ring-down spectroscopy with a narrow bandwidth laser and use pressure scans to increase the accuracy of the measured oxygen extinction coefficients. We use the so-called Adjustable Branch Coupling model to describe line mixing in the magnetic allowed A-Band dipole absorption and we retrieve the collision induced absorption spectrum due to N$_2$-O$_2$ collisions.