Isca, v1.0: a framework for the global modelling of the atmospheres of Earth and other planets at varying levels of complexity

Abstract. Isca is a framework for the idealized modelling of the global circulation of planetary atmospheres at varying levels of complexity and realism. The framework is an outgrowth of models from the Geophysical Fluid Dynamics Laboratory in Princeton, USA, designed for Earth's atmosphere, but it may readily be extended into other planetary regimes. Various forcing and radiation options are available, from dry, time invariant, Newtonian thermal relaxation to moist dynamics with radiative transfer. Options are available in the dry thermal relaxation scheme to account for the effects of obliquity and eccentricity (and so seasonality), different atmospheric optical depths and a surface mixed layer. An idealized grey radiation scheme, a two-band scheme, and a multiband scheme are also available, all with simple moist effects and astronomically based solar forcing. At the complex end of the spectrum the framework provides a direct connection to comprehensive atmospheric general circulation models. For Earth modelling, options include an aquaplanet and configurable continental outlines and topography. Continents may be defined by changing albedo, heat capacity, and evaporative parameters and/or by using a simple bucket hydrology model. Oceanic Q  fluxes may be added to reproduce specified sea surface temperatures, with arbitrary continental distributions. Planetary atmospheres may be configured by changing planetary size and mass, solar forcing, atmospheric mass, radiation, and other parameters. Examples are given of various Earth configurations as well as a giant planet simulation, a slowly rotating terrestrial planet simulation, and tidally locked and other orbitally resonant exoplanet simulations. The underlying model is written in Fortran and may largely be configured with Python scripts. Python scripts are also used to run the model on different architectures, to archive the output, and for diagnostics, graphics, and post-processing. All of these features are publicly available in a Git-based repository.

[1]  S. Moorthi,et al.  Relaxed Arakawa-Schubert - A parameterization of moist convection for general circulation models , 1992 .

[2]  A. Betts,et al.  A new convective adjustment scheme. Part II: Single column tests using GATE wave, BOMEX, ATEX and arctic air‐mass data sets , 1986 .

[3]  M. Latif,et al.  State dependence of atmospheric response to extratropical North Pacific SST anomalies , 2016 .

[4]  J. Haigh,et al.  The effects of increasing humidity on heat transport by extratropical waves , 2016 .

[5]  Heiko Jansen,et al.  The Planet Simulator: Towards a user friendly model , 2005 .

[6]  M. Blackburn,et al.  Further Investigation of the Impact of Idealized Continents and SST Distributions on the Northern Hemisphere Storm Tracks , 2012 .

[7]  A. Nikoghossian.  Radiative Transfer in Inhomogeneous Atmospheres. I , 2004 .

[8]  M. Suárez,et al.  A proposal for the intercomparison of the dynamical cores of atmospheric general circulation models , 1994 .

[9]  S. Manabe.  CLIMATE AND THE OCEAN CIRCULATION1 , 1969 .

[10]  G. Vallis.  Atmospheric and Oceanic Fluid Dynamics: Fundamentals and Large-Scale Circulation , 2017 .

[11]  G. Vallis,et al.  Regime Change Behavior during Asian Monsoon Onset , 2017 .

[12]  N. Wood,et al.  The unified model, a fully-compressible, non-hydrostatic, deep atmosphere global circulation model, applied to hot Jupiters - ENDGame for a HD 209458b test case , 2014 .

[13]  James Manners,et al.  Exploring the climate of Proxima B with the Met Office Unified Model (Corrigendum) , 2017, Astronomy & Astrophysics.

[14]  T. Schneider,et al.  The Hydrological Cycle over a Wide Range of Climates Simulated with an Idealized GCM , 2008 .

[15]  M. Byrne.  Land–Ocean Warming Contrast over a Wide Range of Climates: Convective Quasi-Equilibrium Theory and Idealized Simulations , 2013 .

[16]  N. A. Phillips,et al.  A COORDINATE SYSTEM HAVING SOME SPECIAL ADVANTAGES FOR NUMERICAL FORECASTING , 1957 .

[17]  Isaac M. Held,et al.  The Gap between Simulation and Understanding in Climate Modeling , 2005 .

[18]  G. Russell,et al.  Research paperSeasonal oceanic heat transports computed from an atmospheric model , 1985 .

[19]  Stephen H. Schneider,et al.  Climate modeling , 1987 .

[20]  G. Vallis.  Geophysical fluid dynamics: whence, whither and why? , 2016, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[21]  E. Mlawer,et al.  Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave , 1997 .

[22]  L. Polvani,et al.  EQUATORIAL SUPERROTATION ON TIDALLY LOCKED EXOPLANETS , 2011, 1103.3101.

[23]  E. Gerber,et al.  Untangling the Annual Cycle of the Tropical Tropopause Layer with an Idealized Moist Model , 2017 .

[24]  Jonathan L. Mitchell,et al.  Locally enhanced precipitation organized by planetary-scale waves on Titan , 2011 .

[25]  M. McIntyre,et al.  Jupiter's unearthly jets: a new turbulent model exhibiting statistical steadiness without large-scale dissipation , 2014, 1412.4684.

[26]  M. Blackburn,et al.  The Basic Ingredients of the North Atlantic Storm Track. Part I: Land-Sea Contrast and Orography , 2009 .

[27]  Shepard A. Clough,et al.  Atmospheric radiative transfer modeling: a summary of the AER codes , 2005 .

[28]  Isaac M. Held,et al.  A Gray-Radiation Aquaplanet Moist GCM. Part II: Energy Transports in Altered Climates , 2007 .

[29]  William Bourke,et al.  A multi-level spectral model. I. Formulation and hemispheric integrations , 1974 .

[30]  J. Thepaut,et al.  The ERA‐Interim reanalysis: configuration and performance of the data assimilation system , 2011 .

[31]  Thomas M. Smith,et al.  Seasonal oceanic heat transports computed from an atmospheric model and ocean temperature climatology , 1989 .

[32]  Stephan Hoyer,et al.  xarray: N-D labeled arrays and datasets in Python , 2017 .

[33]  Giuseppe Piccioni,et al.  Variable winds on Venus mapped in three dimensions , 2008 .

[34]  C. Kobayashi,et al.  The JRA-55 Reanalysis: General Specifications and Basic Characteristics , 2015 .

[35]  G. Rybicki.  Radiative transfer , 2019, Climate Change and Terrestrial Ecosystem Modeling.

[36]  Jonathan L. Mitchell,et al.  The dynamics behind Titan's methane clouds , 2006, Proceedings of the National Academy of Sciences.

[37]  Catherine Gautier,et al.  SBDART: A Research and Teaching Software Tool for Plane-Parallel Radiative Transfer in the Earth's Atmosphere. , 1998 .

[38]  T. Schneider,et al.  Atmospheric Dynamics of Earth‐Like Tidally Locked Aquaplanets , 2010, 1001.5117.

[39]  David Charbonneau,et al.  ATMOSPHERIC CIRCULATION OF HOT JUPITERS: COUPLED RADIATIVE-DYNAMICAL GENERAL CIRCULATION MODEL SIMULATIONS OF HD 189733b and HD 209458b , 2008, 0809.2089.

[40]  Isaac M. Held,et al.  A Gray-Radiation Aquaplanet Moist GCM. Part I: Static Stability and Eddy Scale , 2006 .

[41]  G. Vallis,et al.  Response of the large‐scale structure of the atmosphere to global warming , 2015 .

[42]  T. Schneider,et al.  Self-Organization of Atmospheric Macroturbulence into Critical States of Weak Nonlinear Eddy-Eddy Interactions , 2006 .

[43]  T. Schneider,et al.  Contrasting responses to orbital precession on Titan and Earth , 2016 .

[44]  T. Schneider,et al.  Formation of Jets and Equatorial Superrotation on Jupiter , 2008, 0809.4302.

[45]  Jonathan L. Mitchell,et al.  Atmospheric superrotation in an idealized GCM: Parameter dependence of the eddy response , 2014 .

[46]  K. Miyakoda,et al.  Reduction of the Gibbs Oscillation in Spectral Model Simulations , 1994 .

[47]  G. Russell,et al.  Annual oceanic heat transports computed from an atmospheric model , 1983 .

[48]  R. Hide.  Dynamics of the Atmospheres of the Major Planets with an Appendix on the Viscous Boundary Layer at the Rigid Bounding Surface of an Electrically-Conducting Rotating Fluid in the Presence of a Magnetic Field , 1969 .

[49]  M. Blackburn,et al.  Context and Aims of the Aqua-Planet Experiment (Special Issue on The Aqua-Planet Experiment Project (APE) and Related Researches) , 2013 .

[50]  Dilbert,et al.  The portable university model of the atmosphere ( PUMA ) : Storm track dynamics and low-frequency variability , 2005 .

[51]  G. Vallis,et al.  The Thermal Phase Curve Offset on Tidally and Nontidally Locked Exoplanets: A Shallow Water Model , 2017, 1704.06813.

[52]  S. Fueglistaler,et al.  IGCM4: a fast, parallel and flexible intermediate climate model , 2014 .

[53]  Brian J. Hoskins,et al.  Dynamical processes in the atmosphere and the use of models , 1983 .

[54]  Robert L. Haney,et al.  On the Pressure Gradient Force over Steep Topography in Sigma Coordinate Ocean Models , 1991 .

[55]  G. Vallis,et al.  On the Zonal Structure of the North Atlantic Oscillation and Annular Modes , 2009 .

[56]  S. Grimm,et al.  THOR: A NEW AND FLEXIBLE GLOBAL CIRCULATION MODEL TO EXPLORE PLANETARY ATMOSPHERES , 2016, 1607.05535.

[57]  Riccardo Farneti,et al.  An Intermediate Complexity Climate Model (ICCMp1) based on the GFDL flexible modelling system , 2009 .

[58]  A..  A new convective adjustment scheme. Part I: Observational and theoretical basis , 2006 .

[59]  W. Stern,et al.  A Description of the GFDL Global Spectral Model , 1982 .