# Thermochemistry and vertical mixing in the tropospheres of Uranus and Neptune: How convection inhibition can affect the derivation of deep oxygen abundances

## TL;DR

This paper investigates how convection inhibition due to water condensation affects the thermal structure and oxygen abundance estimates in Uranus and Neptune's atmospheres, using updated models and observations.

## Contribution

It introduces a revised atmospheric model that accounts for convection inhibition, leading to more accurate deep oxygen abundance estimates in ice giant planets.

## Key findings

- Convection inhibition significantly alters the thermal profile.
- Revised models suggest different oxygen enrichment levels.
- Current limitations of the modeling approach are discussed.

## Abstract

Thermochemical models have been used in the past to constrain the deep oxygen abundance in the gas and ice giant planets from tropospheric CO spectroscopic measurements. Knowing the oxygen abundance of these planets is a key to better understand their formation. These models have widely used dry and/or moist adiabats to extrapolate temperatures from the measured values in the upper troposphere down to the level where the thermochemical equilibrium between H$_2$O and CO is established. The mean molecular mass gradient produced by the condensation of H$_2$O stabilizes the atmosphere against convection and results in a vertical thermal profile and H$_2$O distribution that departs significantly from previous estimates. We revisit O/H estimates using an atmospheric structure that accounts for the inhibition of the convection by condensation. We use a thermochemical network and the latest observations of CO in Uranus and Neptune to calculate the internal oxygen enrichment required to satisfy both these new estimates of the thermal profile and the observations. We also present the current limitations of such modeling.