Presentation #102.287 in the session Poster Session.
Empirical constraints of fundamental properties of protoplanetary disks are important for understanding planet formation and planetary properties. Disk properties are often determined from observations of carbon monoxide (CO) gas in the upper warm disk layers that may not trace bulk disk properties. Also, estimates of properties using different tracers vary significantly, indicating that CO is depleted relative to expected values. Previous models of ice formation, chemistry, and transport, could not explain CO depletion on observed ~1 Myr timescales. I will discuss a new non-equilibrium mechanism for CO ice-formation and evolution that explains the observed distribution, abundance, and time evolution of CO gas in four well-studied protoplanetary disks. Using this method, we can constrain three crucial parameters that control planetary formation: the solid and gaseous CO inventory at the disk midplane, the disk diffusivities, and the disk mass (where we resolve inconsistencies in estimates from other mass tracers).