ATMOSPHERIC HEAT REDISTRIBUTION ON HOT JUPITERS

By D. Perez-Becker, A. Showman. 2013

137 citations recorded by the source corpus.

Infrared light curves of transiting hot Jupiters present a trend in which the atmospheres of the hottest planets are less efficient at redistributing the stellar energy absorbed on their daysides—and thus have a larger day–night temperature contrast—than colder planets. To this day, no predictive atmospheric model has been published that identifies which dynamical mechanisms determine the atmospheric heat redistribution efficiency on tidally locked exoplanets. Here we present a shallow-water model of the atmospheric dynamics on synchronously rotating planets that explains why heat redistribution efficiency drops as stellar insolation rises. Our model shows that planets with weak friction and weak irradiation exhibit a banded zonal flow with minimal day–night temperature differences, while models with strong irradiation and/or strong friction exhibit a day–night flow pattern with order-unity fractional day–night temperature differences. To interpret the model, we develop a scaling theory which shows that the timescale for gravity waves to propagate horizontally over planetary scales, τwave, plays a dominant role in controlling the transition from small to large temperature contrasts. This implies that heat redistribution is governed by a wave-like process, similar to the one responsible for the weak temperature gradients in the Earth's tropics. When atmospheric drag can be neglected, the transition from small to large day–night temperature contrasts occurs when , where τrad is the radiative relaxation time and Ω is the planetary rotation frequency. Alternatively, this transition criterion can be expressed as τrad ∼ τvert, where τvert is the timescale for a fluid parcel to move vertically over the difference in day–night thickness. These results subsume the more widely used timescale comparison for estimating heat redistribution efficiency between τrad and the horizontal day–night advection timescale, τadv. Only because τadv ∼ τvert for hot Jupiters does the commonly assumed timescale comparison between τrad and τadv yield approximately correct predictions for the heat redistribution efficiency.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/421bcf0e0493d7b3b289ca70f1984bacdd76b227

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. D. Sing
5. D. Deming
6. M. Line
7. J. D'esert
8. H. Knutson

In Instrumentation

1. Jon Fortney
2. N. Madhusudhan
3. A. Showman
4. D. Sing
5. M. Line
6. J. D'esert
7. H. Knutson
8. D. Deming

In Statistical and Nonlinear Physics

1. N. Madhusudhan
2. Jon Fortney
3. M. Line
4. A. Showman
5. H. Knutson
6. V. Parmentier
7. J. D'esert
8. M. Marley

Citations in the corpus

• H− Opacity and Water Dissociation in the Dayside Atmosphere of the Very Hot Gas Giant WASP-18b (2018, methodology): “Our retrieved value of f=2.03 ± 0.08 is consistent with minimal day-night redistribution expected for such a hot planet (Perez-Becker & Showman 2013) and measured by Maxted et al. (2013).”
• SPECTROSCOPIC EVIDENCE FOR A TEMPERATURE INVERSION IN THE DAYSIDE ATMOSPHERE OF HOT JUPITER WASP-33b (2015, methodology): “Our inference of TiO supports previous theoretical predictions that TiO should be abundant in the hottest of oxygen-rich hot Jupiters, due to the lack of an effective vertical or day-night cold trap (Perez-Becker & Showman 2013; Parmentier et al. 2013).”
• SPITZER PHASE CURVE CONSTRAINTS FOR WASP-43b AT 3.6 AND 4.5 μm (2016, methodology): “Next, we note that the waveadjustment mechanism described by Perez-Becker & Showman (2013) and Komacek & Showman (2016) operates most efficiently within the equatorial wave guide.”
• HST hot-Jupiter transmission spectral survey: evidence for aerosols and lack of TiO in the atmosphere of WASP-12b (2013, background): “The efficiency of redistribution is primarily governed by the ratio of advective to radiative timescales, with hotter planets tend to have shorter radiative timescales and thus larger day/night contrasts (Showman & Guillot 2002; Perna et al. 2012; Cowan et al. 2012; Perez-Becker & Showman 2013).”
• Global Climate and Atmospheric Composition of the Ultra-hot Jupiter WASP-103b from HST and Spitzer Phase Curve Observations (2018, background): “Fast radiative timescales are predicted at high temperatures, and small hotspot offsets are also observed for other very hot Jupiters (Perez-Becker & Showman 2013; Komacek & Showman 2016; Komacek et al. 2017).”
• SPITZER SECONDARY ECLIPSES OF THE DENSE, MODESTLY-IRRADIATED, GIANT EXOPLANET HAT-P- 20 b ?> USING PIXEL-LEVEL DECORRELATION (2014, background): “Cowan & Agol (2012) studied the statistics of heat re-distribution using secondary eclipse data, and Perez-Becker & Showman (2013) studied heat redistribution using phase curves.”
• TRANSITIONS IN THE CLOUD COMPOSITION OF HOT JUPITERS (2016, background): “…of σ = 1.05 around the mean particle size in order to smooth the Mie bumps in the opacities. temperature variation across the dayside increases with the equilibrium temperature, as does the day/night temperature contrast (Perna et al. 2012; Perez-Becker & Showman 2013; Komacek & Showman 2016).”