Lorenz Energy Cycle: Another Way to Understand the Atmospheric Circulation on Tidally Locked Terrestrial Planets

Abstract

In this study, we employ and modify the Lorenz energy cycle (LEC) framework as another way to understand the atmospheric circulation on tidally locked terrestrial planets. It well describes the atmospheric general circulation in the perspective of energy transformation, involved with several dynamical processes. We find that on rapidly rotating, tidally locked terrestrial planets, mean potential energy (P${}_{\mathrm{M}}$) and eddy potential energy (P${}_{\mathrm{E}}$) are comparable to those on Earth, as they have similar steep meridional temperature gradients. Mean kinetic energy (K${}_{\mathrm{M}}$) and eddy kinetic energy (K${}_{\mathrm{E}}$) are larger than those on Earth, related to stronger winds. The two conversion paths, P${}_{\mathrm{M}}\to$P${}_{\mathrm{E}}\to$K${}_{\mathrm{E}}$ and P${}_{\mathrm{M}}\to$K${}_{\mathrm{M}}\to$K${}_{\mathrm{E}}$, are both efficient. The former is associated with strong baroclinic instabilities, and the latter is associated with Hadley cells. On slowly rotating, tidally locked terrestrial planets, weak temperature gradients in the free atmosphere and strong nightside temperature inversion make P${}_{\mathrm{M}}$ and P${}_{\mathrm{E}}$ are much smaller than those on Earth. Meanwhile, large day--night surface temperature contrast and small rotation rate make the overturning circulation extend to the globe, so that the main conversion path is P${}_{\mathrm{M}}\to$K${}_{\mathrm{M}}\to$K${}_{\mathrm{E}}$. This study shows that the LEC analyses improve the understanding of the atmospheric circulation on tidally locked terrestrial planets.

25 pages, 16 fugures

References in corpus (18)

• Strong Dependence of the Inner Edge of the Habitable Zone on Planetary Rotation Rate
• Atmospheric dynamics of Earth-like tidally locked aquaplanets
• 3D Structures of equatorial waves and the resulting superrotation in the atmosphere of a tidally locked hot Jupiter
• Constraints on Climate and Habitability for Earth-like Exoplanets Determined from a General Circulation Model
• The rotational and divergent components of atmospheric circulation on tidally locked planets
• Deciphering thermal phase curves of dry, tidally locked terrestrial planets
• The TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI). Part II: Moist Cases -- The Two Waterworlds
• The TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI). Part I: Dry Cases -- The fellowship of the GCMs
• The Equatorial Jet Speed on Tidally Locked Planets: I -- Terrestrial Planets
• The Acceleration of Superrotation in Simulated Hot Jupiter Atmospheres
• Stabilization of dayside surface liquid water via tropopause cold trapping on arid slowly rotating tidally locked planets
• Earth${}^{\prime }$s polar night boundary layer as an analogue for dark side inversions on synchronously rotating terrestrial exoplanets
• How does Background Air Pressure Influence the Inner Edge of the Habitable Zone for Tidally Locked Planets in a 3D View?
• A New Line-By-Line General Circulation Model for Simulations of Diverse Planetary Atmospheres: Initial Validation and Application to the Exoplanet GJ 1132b
• Phase Shift of Planetary Waves and Wave--Jet Resonance on Tidally Locked Planets
• Atmospheric Overturning Circulation on Dry, Tidally-locked Rocky Planets is Mainly Driven by Radiative Cooling
• Multiple moist climate equilibrium states on arid rocky M-dwarf planets: A last-saturation tracer analysis
• The Phase-curve Signature of Condensible Water-rich Atmospheres on Slowly Rotating Tidally Locked Exoplanets

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