Exoclimes_Conference_booklet1

the climate on exoplanets by providing important species affecting radiation. On the other
hand, climate may pose important constraints on atmospheric composition, based on
which different schemes of photochemistry can perform. In this work we will discuss the
interplays between exoplanet climate and atmospheric composition and photochemistry,
focusing on potentially habitable exoplanets such as HD40307g and the GJ667C planets.
Water loss from terrestrial planets with N2/CO2 atmospheres!
Robin!Wordsworth! — University of Chicago!
The initial volatile content delivered to terrestrial planets during accretion is most likely
highly variable, with many planets receiving significantly more than Earth today possesses.
Understanding how later processes such as photolysis-driven H2O loss affect planetary
evolution is therefore vital to constraining the range of possibilities for both the early Solar
System and for many recently discovered low-mass exoplanets. Here we discuss a range
of calculations we have performed to study the dependence of water loss rates on a wide
range of planetary parameters. We show through a combination of simple analysis and
numerical climate models (1D and 3D) that the non-condensing atmospheric component
plays a fundamental role in controlling water loss via regulation of the stratospheric cold
trap. While CO2 can increase H2O transport to the high atmosphere over a small range of
mixing ratios by increasing surface temperature, thermodynamic constraints and cooling of
the middle/upper atmosphere act as a bottleneck on escape in other circumstances. The
differing relationships of total stellar luminosity and stellar XUV with time for G-stars places
strong limits on H2O loss rates for planets like Earth, although escape can reach higher
values for planets with surface liquid water around M-stars. Because the carbon cycles of
planets with ocean-covered surfaces are likely to be fundamentally different from that of
Earth, our results have important implications for the likely surface and atmospheric
characteristics of super-Earth exoplanets in the habitable zone.
Oceanic Circulation of Tidally Locked Terrestrial Planets!
Jun Yang — University of Chicago!
A fully coupled oceanic-atmospheric general circulation model is modified to simulate the
climate of tidally locked terrestrial planets. A central issue to be examined is to identify the
determining factors of oceanic circulation and its associated heat transport in both zonal
and meridional directions. In this study we will examine five planetary parameters: ocean
depth, land-sea distribution, rotational period (equaling to orbital period), planetary radius,
and gravity.
All these simulations show an eastward current along the equator, transporting heat from
dayside to nightside, and a meridional overturning circulation (MOC) in each hemisphere,
transporting heat from tropics to high latitudes. The equatorial current is driven by the
combined effect of surface wind streeses and Rossby waves in the ocean which transport
eastward momentum from high latitudes to the equator. The MOC is driven by salinity and/
or temperature contrasts between low and high latitudes. The salinity contrast results from
sea ice formation at high latitudes which releases salt to the ocean, and from sea ice
melting at low-latitude ice margins which decreases the salinity there. The strengths of the
oceanic circulation and heat transport are signifcantly influenced by the five planetary
parameters. We will further present how these parameters work.
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