Exoclimes_Conference_booklet1

circulations with an idealized General Circulation Model (GCM), in which an atmospheric
model with idealized physics is coupled to an aquaplanet slab ocean of fixed depth and the
top-of-atmosphere insolation is varied seasonally. A broad range of circulation regimes is
studied by changing the thermal inertia of the slab ocean, the planet rotation rate and
radius while keeping the seasonal cycle of insolation fixed. The climates of Earth, Mars
and Titan will be discussed in this context, and implications for classifying exoplanet
climates will be drawn.
A search for hot water vapor in the atmosphere of Venus during the 2012 transit
Daniel Gisler — Kiepenheuer-Institut für Sonnenphysik
We have observed the Venus transit in 2012 using the Scatter-free Observatory for Limb
Active Regions and Coronae (SOLARC), located on the summit of Haleakala, Maui. The
SOLARC is a 45 cm off-axis Gregorian telescope. This telescope design minimizes
scattered light, that is critical for photon-limited observations. The data has been collected
with the Optical Fiber Imaging Spectralpoarimeter (OFIS). Our goal is to search for water
vapor lines absorbing solar light passing through the Venusian atmosphere and evaluate
the sensitivity of our spectropolarimetric technique to detect water and other constituents
in atmospheres of transiting exoplanets. Here we present the data and analyze Stokes I,
Q, U spectra extracted from the solar disk and the Venus limb and night side. We estimate
limits on the water vapor partial pressure and compare these with measurements by space
missions and probes.
Development of a new Global Climate Model of Saturn's stratosphere
Sandrine Guerlet — Laboratoire de Météorologie Dynamique, Paris!
Recent observations of Saturn’s stratospheric thermal structure and composition have
revealed new phenomena: an equatorial oscillation in temperature, reminiscent of the
Earth's Quasi-Biennal Oscillation ; strong meridional contrasts of hydrocarbons ; a warm
“beacon” associated with the powerful 2010 storm. Those signatures cannot be
reproduced by 1D photochemical and radiative models and suggest that atmospheric
dynamics plays a key role. This motivated us to develop a complete 3D General
Circulation Model (GCM) for Saturn, based on the LMD’s hydrodynamical core, to explore
the circulation, seasonal variability, and wave activity in Saturn's atmosphere.
In order to closely reproduce Saturn's radiative forcing, a particular emphasis was put in
obtaining fast and accurate radiative transfer calculations. Our radiative model uses
correlated-k distributions and spectral discretization tailored for Saturn's atmosphere. We
include an internal heat flux, ring shadowing and both tropospheric and stratospheric
aerosols.
Firstly, we will present a comparison of temperature fields obtained with this new
seasonal, radiative equilibrium model to that inferred from Cassini/CIRS observations.
Even in the absence of dynamics, our model qualitatively reproduces the overall
meridional temperature gradient between the summer and the winter hemispheres in the
lower stratosphere except in the equatorial region, where the temperature structure is
governed by the dynamical equatorial oscillation. Our model can also reproduce the
“temperature knee” observed around 200 mbar, which is caused by heating at the top of
the tropospheric aerosol layer.
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