Frequency-stabilized cavity ring-down spectroscopy measurements of line mixing and collision-induced absorption in the O2 A-band.

Frequency-stabilized cavity ring-down spectroscopy measurements were performed in the P-branch of the O(2) A-band [b(1)Σ(g) (+) ← X (3)Σ(g) (-)(0,0)] near atmospheric pressure. Line mixing parameters and collision-induced absorption were quantified and reported. These measurements show qualitative differences with those taken at relatively high pressure (2 MPa-20 MPa). We also assess the implications of these measurements on atmospheric retrievals.