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Radiative Feedback of Photochemical Hazes in 3D Simulations of Hot Jupiters

Presentation #102.215 in the session Poster Session.

Published onJun 20, 2022
Radiative Feedback of Photochemical Hazes in 3D Simulations of Hot Jupiters

To date, 3D simulations of aerosols in the atmospheres of extrasolar giant planets have almost exclusively focused on condensate clouds. However, for relatively cool hot Jupiters, photochemical hazes are expected to be an important source of opacity. As 1D radiative transfer models show, absorption and scattering from photochemical hazes can change the temperature profile by several hundred Kelvin in these planets. Here, we present 3D simulations of hot Jupiter HD 189733b using SPARC/MITgcm that include radiative feedback from photochemical hazes. We simulated photochemical hazes as radiatively active tracers with a constant particle size of 3 nm. For our nominal simulations, we assumed a soot-like complex refractive index. To explore the dependence on the assumed optical properties, we also performed simulations with a refractive index based on Titan-like hazes.

In all simulations with haze radiative feedback, a strong temperature inversion at low pressures forms on the dayside. The response of the atmospheric circulation and the detailed temperature structure strongly depend on the assumed optical properties of the hazes. For soot-like hazes, the equatorial jet slows down and broadens at low pressures. Vertical velocities increase, especially upwelling near the terminator and on the dayside. For Titan-like hazes, the strength of the equatorial jet increases substantially, especially at low pressures. This results in a 3D haze distribution that differs dramatically from simulations without haze feedback or with soot-like hazes. While in simulations with soot-like hazes or without haze feedback, hazes are most concentrated on the nightside and the morning terminator, with lower haze abundances on the dayside and evening terminator, Titan-like hazes are most abundant on the dayside, the evening terminator and in the equatorial region on the nightside.

The changed temperature structure affects the model-predicted dayside emission spectrum and phase curve in the near- and mid-infrared, with changes particularly large in the near-infrared water bands and at wavelengths >4 μm, for both soot- and Titan-like hazes. In the dayside emission spectrum, the amplitude of the water absorption features is reduced. For the largest haze production rates for soot-like hazes, water is seen in emission rather than in absorption in multiple wavelength regions. The phase curve amplitude increases substantially at most infrared wavelengths when including haze feedback.

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