Wild and Windy Exoplanets

reporting by Helen Hill for MITgcm

Maria Steinrueck is a fourth-year graduate student at the Lunar and Planetary Laboratory (LPL) at the University of Arizona who uses three-dimensional numerical fluid simulations to study the atmospheres of exoplanets. A particular interest is in so-called hot Jupiters. “The tidal locking of these close-in gas giants creates strong day-night temperature contrasts which drive a fascinating atmospheric circulation dominated by an eastward equatorial jet,” explains Steinrueck. “In my research, I am examining how this circulation shapes chemical processes, such as disequilibrium chemistry, cloud or haze formation, as well as how these processes, in turn, influence the atmospheric circulation and radiative transfer.”

In particular, Steinrueck has been looking at the impact the strong winds on hot Jupiters can be expected to have on the distribution of methane and carbon monoxide, two important infrared absorbers. “In the absence of an atmospheric circulation,” she says,” one might expect to find carbon monoxide on the day side and methane on the night side; an assumption (called equilibrium chemistry) that has been used in many models, including most 3D simulations of hot Jupiter atmospheres with realistic radiative transfer.” She continues, “Taking into account the strong winds, however, the methane and carbon monoxide abundances can be expected to be homogenized between day and night sides, as the winds transport gases faster than chemical reactions can take place.”

Hypothesizing that including this effect in her simulations might explain a discrepancy researchers see between observed and simulated light curves of hot Jupiters, Steinrueck decided to take a look at the impact of including this effect of disequilibrium chemistry in a 3D simulation of hot Jupiter HD 189733b, the closest transiting hot Jupiter to Earth found to date. Her findings, co-authored with Vivien Parmentier (Oxford University, UK), Adam Showman and Joshua Lothringer also from LPL, together with Roxana Lupu from NASA Ames are published in The Astrophysical Journal.

Steinrueck and her co-authors used the Substellar and Planetary Atmospheric Radiation and Circulation (SPARC) model (Showman et al, 2009), which uses the MITgcm hydrodynamic kernel to model the atmospheric dynamics and the radiative model of McKay, Marley, Fortney, and collaborators for the radiation (eg Marley, M. S., and C. P. McKay, 1999). All previous studies of hot Jupiters using the SPARC/MITgcm utilized radiation transfer tables calculated assuming equilibrium chemistry. To explore the effect of transport-induced disequilibrium carbon chemistry, Steinrueck et al instead assumed that the methane to carbon monoxide ratio in their runs was “quenched to a constant value throughout the entire atmosphere.”

“I found that including disequilibrium chemistry leads to significant temperature changes (larger than 50-100 K) in simulations of hot Jupiter HD 189733b,” says Steinrueck. “If carbon monoxide is the dominant carbon species in chemical disequilibrium, the day side cools and the night side heats up.”

“In the less likely methane dominated regime, the atmosphere becomes hotter than in the equilibrium chemistry case everywhere on the planet for pressures larger than 30 mbar. Looking at observations predicted from our model, I showed that disequilibrium chemistry cannot explain the observed discrepancies. In fact, while there is little effect on the light curve in the Spitzer 4.5 micron band, the day-night contrast in the 3.6 micron band becomes much smaller when including disequilibrium chemistry—the opposite of what is needed to match observations! As a result, I had to conclude that other effects not included in our model, most likely night side clouds, must be responsible for these discrepancies.”

To find out more about this work contact Maria

This Month’s Featured Publication

Related Publication:

Showman, A.P., J.J. Fortney, Y. Lian, M.S. Marley, R.S. Freedman, H.A. Knutson, and D. Charbonneau (2009), Atmospheric circulation of hot Jupiters: Coupled radiative-dynamical general circulation model simulations of HD 189733b and HD 209458b. Astrophys. J., doi: 10.1088/0004-637X/699/1/564

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Jarle Berntsen, Guttorm Alendal, Helge Avlesen (2019), The role of eddies on pathways, transports, and entrainment in dense water flows along a slope, Ocean Dynamics, doi: 10.1007/s10236-019-01276-0

A. Bower, S. Lozier, A. Biastoch, K. Drouin, N. Foukal, H. Furey, M. Lankhorst, S. Rühs, S. Zou (2019), Lagrangian Views of the Pathways of the Atlantic Meridional Overturning Circulation, Journal of Geophysical Research – Oceans, doi: 10.1029/2019JC015014

Ruichen Cao, Shuya Wang, Guohui Xu, and Xianqing (2019), Characteristics of liquefied soil motion in wavy environment, Physics of Fluids, doi: 10.1063/1.5098507

Michael Doron, Idan Segev, Dafna Shahaf (2019), Discovering Unexpected Local Nonlinear Interactions in scientific Black-box Models, Association of Computing Machinery, Research Track Paper, doi: 10.1145/3292500.3330886

Carsten Eden, Manita Chouksey, and Dirk Olbers (2019), Gravity wave emission by shear instability, Journal of Physical Oceanography, doi: 10.1175/JPO-D-19-0029.1

Julia Gottschalk, Gianna Battaglia, Hubertus Fischer, Thomas L. Frölicher, Samuel L. Jaccard, Aurich Jeltsch-Thömmes, Fortunat Joos, Peter Köhler, Katrin J. Meissner, Laurie Menviel, Christoph Nehrbass-Ahles, Jochen Schmitt, Andreas Schmittner, Luke C. Skinner, Thomas F. Stocker (2019), Mechanisms of millennial-scale atmospheric CO₂ change in numerical model simulations, Quaternary Science Reviews, doi: 10.1016/j.quascirev.2019.05.013

Shijian Hu, Ying Zhang, Ming Feng, Yan Du, Janet Sprintall, Fan Wang, Dunxin Hu, Qiang Xie, Fei Chai (2019), Interannual to decadal variability of upper ocean salinity in the southern Indian Ocean and the role of the Indonesian Throughflow, Journal of Climate, doi: 10.1175/JCLI-D-19-0056.1

Christian Katlein, Stefanie Arndt, H. Jakob Belter, Giulia Castellani, Marcel Nicolaus (2019), Seasonal evolution of light transmission distributions through Arctic sea ice, Journal of Geophysical Research – Oceans, doi: 10.1029/2018JC014833

Qiang Li, Xianzhong Mao, Guotong Deng, Ruixiang Zhao, Chuanzheng Zhang, Xiaohua Zhu (2019), Internal Tide Generation and Dissipation by Small Periodic Topography in Deep Ocean, Journal fo the Ocean University of China, doi: 10.1007/s11802-019-3966-7

Xi Liang, Martin Losch, Lars Nerger, Longjiang Mu, Qinghua Yang, Chengyan Liu (2019), Using Sea Surface Temperature Observations to Constrain Upper Ocean Properties in an Arctic Sea Ice‐Ocean Data Assimilation System, Journal of Geophysical Research – Oceans, doi: 10.1029/2019JC015073

Pablo Lorente, Marcos García-Sotillo, Arancha Amo-Baladrón, Roland Aznar, Bruno Levier, José C. Sánchez-Garrido, Simone Sammartino, Álvaro de Pascual-Collar, Guillaume Reffray, Cristina Toledano, and Enrique Álvarez-Fanjul (2019), Skill assessment of global, regional, and coastal circulation forecast models: evaluating the benefits of dynamical downscaling in IBI (Iberia–Biscay–Ireland) surface waters, Ocean Sci., doi: 10.5194/os-15-967-2019

Anna Pagnone, Christoph Völker, Ying Ye (2019), Processes affecting dissolved iron across the Subtropical North Atlantic: a model study, Ocean Dynamics, doi: 10.1007/s10236-019-01288-w

T. Radko and D. Lewis,(2019), The Age of a Wake, Physics of Fluids, doi: 10.1063/1.5100969

Christopher J. Roach, Kevin Speer (2019), Exchange of Water Between the Ross Gyre and ACC Assessed by Lagrangian Particle Tracking, Journal of Geophysical Research – Oceans, doi: 10.1029/2018JC014845

Rodriguez, Angelica R (2019), Buoyancy transport mechanisms at continental shelf, surf zone, and estuarine scales, UC San Diego Doctoral Dissertation [pdf]

Joseph Skitka, J.B. Marston, Baylor Fox-Kemper (2019), Reduced-Order Quasilinear Model of Ocean Boundary-Layer Turbulence, arXiv: 1906.11671 [physics.ao-ph]

Maria E. Steinrueck, Vivien Parmentier, Adam P. Showman, Joshua D. Lothringer, and Roxana E. Lupu (2019), The Effect of 3D Transport-induced Disequilibrium Carbon Chemistry on the Atmospheric Structure, Phase Curves, and Emission Spectra of Hot Jupiter HD 189733b, The Astrophysical Journal, doi: 10.3847/1538-4357/ab2598

J.N. Stroh, Gleb Panteleev, Max Yaremchuk, Oceana Francis, Richard Allard (2019), Toward optimization of rheology in sea ice models through data assimilation, Journal of Atmospheric and Oceanic Technology, doi: 10.1175/JTECH-D-18-0239.1

Guang J. Zhang, Xiaoliang Song, Yong Wang (2019), The double ITCZ syndrome in GCMs: A coupled feedback problem among convection, clouds, atmospheric and ocean circulations, Atmospheric Research, doi: 10.1016/j.atmosres.2019.06.023

Jicai Zhang, Guoqing Li, Jiacheng Yi, Yanqiu Gao, and Anzhou Cao (2019), A Method on Estimating Time-Varying Vertical Eddy Viscosity for An Ekman Layer Model with Data Assimilation, Journal of Atmospheric and Oceanic Technology, doi: 10.1175/JTECH-D-18-0223.1

Do you have news about research using MITgcm? We are looking for contributions to these pages. If you have an interesting MITgcm project (ocean, atmosphere, sea-ice, physics, biology or otherwise) that you want to tell people about, get in touch. To make a post, contact Helen