A simple model for radiative and convective fluxes in planetary atmospheres

Juan P. Tolento, Tyler D. Robinson

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

One-dimensional (vertical) models of planetary atmospheres typically balance the net solar and internal energy fluxes against the net thermal radiative and convective heat fluxes to determine an equilibrium thermal structure. Thus, simple models of shortwave and longwave (optical and infrared) radiative transport can provide insight into key processes operating within planetary atmospheres. Here, we develop a simple, analytic expression for both the downwelling thermal and net thermal radiative fluxes in a planetary troposphere. For thermal wavelengths, we assume that the atmosphere is non-scattering and that opacities are grey (i.e., wavelength-independent). Additionally, we adopt an atmospheric thermal structure that follows a modified dry adiabat as well as a physically-motivated power-law relationship between grey thermal optical depth and atmospheric pressure. To verify aspects of our analytic treatment, we compare our model to more sophisticated “full physics” tools as applied to Venus, Earth, and a cloudfree Jupiter, thereby exploring a diversity of atmospheric conditions. Next, we seek to better understand our analytic model by exploring how thermal radiative flux profiles respond to variations in key physical parameters, such as the total grey thermal optical depth of the atmosphere. Using energy balance arguments, we derive convective flux profiles for the tropospheres of all Solar System worlds with thick atmospheres, and propose a scaling that enables inter-comparison of these profiles. Lastly, we use our analytic treatment to discuss the validity of other simple models of convective fluxes in planetary atmospheres. Our new expressions build on decades of analytic modeling exercises in planetary atmospheres, and further prove the utility of simple, generalized tools in comparative planetology studies.

Original languageEnglish (US)
Pages (from-to)34-45
Number of pages12
JournalIcarus
Volume329
DOIs
StatePublished - Sep 1 2019

Keywords

  • Atmospheres
  • Jovian planets
  • Radiative transfer
  • Structure
  • Terrestrial planets

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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