Modellizzazione della temperatura superficiale di pianeti di tipo terrestre

Giovanni Vladilo (1,2), Giuseppe Murante (1), Laura Silva (1), Antonello Provenzale (3)

(1) INAF - Osservatorio Astronomico di Trieste(2) University of Trieste, Department of Physics

(3) Institute of Atmospheric Sciences and Climate (ISAC)-CNR, Torino

Gaia Ferri(2), Gregorio Ragazzini (2), Salvatore Scarpato(2), Matteo Pinamonti(2)

Goals

Use climate models to estimate the planet surface temperature as a function of time and latitude

Use the temperatures predicted by the modelto quantify the surface habitabiliy of the planet

Climate tools used in studies of habitability

Single atmospheric column calculationsUsed in classic work on the habitable zone

Energy Balance ModelsUsed to explore a range of planetary parameters

We use a combination of these tools

Zonal & seasonal EBMProt << Porb

Set of equations (one for each latitude zone)

Exact calculation of S(φ,t) as a function of orbital eccentricity and axis obliquity

Incoming stellar radiation

Thermal capacity

Surface albedo

Schematic geography: fo,i

We are currentlyusing CCM routineswhich are part of the NCAR climate model

Top-of-atmosphere OLR and albedo

Diffusion term

Parametrization of the diffusion term D

Currently using a parametrization proposed by Barry et al. (2002) based on GCM experiments

Validation of the diffusion term D

EBM calibration with Earth data

Anctartica not reproduced becauseorography is not featured in EBMs

Examples of results

Impact of planetary properties onseasonal-latitudinal temperature maps

Rotation period and climate

Surface pressure and climate

Axis obliquity and climate

Planet radius and climate

Tidal heating and climate

Tesi M. Pinamonti (2014)

Why using our climate tools instead of GCMs ?

EBMs

GCMs

weeks

CPU time

minutes

days, but only once

Single-columncalculations

EBMs

GCMs

hard to assess the interplay

between different climate

factors

easy to isolate the role of

different physical effects

Interpretation of the model predictions

Single-columncalculations

EBMs

GCMs

3D model results sensitive to the

orography, which is unknown

surface distribution of continents can be treated in a schematic way

Requirement of input parameters

Single-columncalculations

Planets should not be tidally locked since the EBM requires Prot << Porb

The exoplanet should be of terrestrial type(in lack of measurements of the planet mean density,one possible selection criterion could be R < 2 R⊕)

Limits of application to exoplanets

The observable physical quantities of exoplanets most relevant for the climate are currently quite limited:

a (semi-major axis), e (eccentricity), L* (stellar luminosity),

but the climate is influenced by many other quantities currently unconstrained by observations

With our climate tools we can:

(1) Explore the parameter space of unconstrained parametersand provide significant insights in the field of planetary habitability

(2) Perform preliminary climate studies of special cases before running CPU-consuming GCMs

Conclusions

Future work

Searching for a more flexible tool for single-column

calculations

Implementing our own 3D model

calculations tailored for testing the diffusion term