# Advection of potential temperature in the atmosphere of irradiated exoplanets: a robust mechanism to explain radius inflation

## TL;DR

This paper proposes a new atmospheric circulation mechanism involving potential temperature advection that explains the inflated radii of irradiated hot Jupiters, aligning well with observed data.

## Contribution

It introduces a robust 2D atmospheric model demonstrating how potential temperature advection causes radius inflation in hot Jupiters, supported by comparison to 3D calculations.

## Key findings

- Reproduces the observed radius of HD209458b
- Explains the correlation between radius inflation and irradiation
- Identifies potential temperature advection as a key inflation mechanism

## Abstract

The anomalously large radii of strongly irradiated exoplanets have remained a major puzzle in astronomy. Based on a 2D steady state atmospheric circulation model, the validity of which is assessed by comparison to 3D calculations, we reveal a new mechanism, namely the advection of the potential temperature due to mass and longitudinal momentum conservation, a process occuring in the Earth's atmosphere or oceans. At depth, the vanishing heating flux forces the atmospheric structure to converge to a hotter adiabat than the one obtained with 1D calculations, implying a larger radius for the planet. Not only do the calculations reproduce the observed radius of HD209458b, but also the observed correlation between radius inflation and irradiation for transiting planets. Vertical advection of potential temperature induced by non uniform atmospheric heating thus provides a robust mechanism explaining the inflated radii of irradiated hot Jupiters.