Geoscientific Model Development www.geosci-model-dev.net 1991-959X 1991-9603 2 1 2009 10.5194/gmd-2-1-2009 http://www.geosci-model-dev.net/2/1/2009/ http://www.geosci-model-dev.net/2/1/2009/gmd-2-1-2009.html http://www.geosci-model-dev.net/2/1/2009/gmd-2-1-2009.pdf 1 11 2009-02-11 qtcm 0.1.2: a Python implementation of the Neelin-Zeng Quasi-Equilibrium Tropical Circulation Model J. W.-B. Lin jlin@northpark.edu Physics Department, North Park University, 3225 W. Foster Ave., Chicago, Illinois 60625, USA Historically, climate models have been developed incrementally and in compiled languages like Fortran. While the use of legacy compiled languages results in fast, time-tested code, the resulting model is limited in its modularity and cannot take advantage of functionality available with modern computer languages. Here we describe an effort at using the open-source, object-oriented language Python to create more flexible climate models: the package qtcm, a Python implementation of the intermediate-level Neelin-Zeng Quasi-Equilibrium Tropical Circulation model (QTCM1) of the atmosphere. The qtcm package retains the core numerics of QTCM1, written in Fortran to optimize model performance, but uses Python structures and utilities to wrap the QTCM1 Fortran routines and manage model execution. The resulting "mixed language" modeling package allows order and choice of subroutine execution to be altered at run time, and model analysis and visualization to be integrated in interactively with model execution at run time. This flexibility facilitates more complex scientific analysis using less complex code than would be possible using traditional languages alone, and provides tools to transform the traditional "formulate hypothesis → write and test code → run model → analyze results" sequence into a feedback loop that can be executed automatically by the computer. Beazley, D M.: SWIG 1.1 Users Manual, http://www.swig.org/Doc1.1/HTML/Contents.html, 1997. Edwards, P N.: A brief history of atmospheric general circulation modeling, in: General Circulation Development, Past Present and Future: The Proceedings of a Symposium in Honor of Akio Arakawa, edited by: Randall, D A., Academic Press, New York, 67–90, 2000. Gushchina, D., Dewitte, B., and Illig, S.: Remote ENSO forcing versus local air-sea interaction in QTCM: A sensitivity study to intraseasonal variability, Adv. Geosci., 6, 289–297, 2006. Hunter, J. and Dale, D.: The Matplotlib User's Guide, http://matplotlib.sourceforge.net/users_guide_0.98.1.pdf, 2007. Johnson, R A.: Object-oriented analysis and design – What does the research say?, J. Comput. Inform. Syst., 42, 11–15, 2002. Lin, J. W.-B.: qtcm User's Guide, http://www.johnny-lin.com/py_pkgs/qtcm/doc/manual.pdf, 2008. Lin, J. W.-B. and Neelin, J D.: Influence of a stochastic moist convective parameterization on tropical climate variability, Geophys. Res. Lett., 27, 3691–3694, 2000. Lin, J. W.-B. and Neelin, J D.: Considerations for stochastic convective parameterization, J. Atmos. Sci., 59, 959–975, 2002. Lin, J. W.-B., Neelin, J D., and Zeng, N.: Maintenance of tropical intraseasonal variability: Impact of evaporation-wind feedback and midlatitude storms, J. Atmos. Sci., 57, 2793–2823, 2000. Mesinger, F. and Arakawa, A.: Numerical Methods Used in Atmospheric Models, Vol. 1, GARP Publications Series No. 17, World Meteorological Organization, 1976. Neelin, J D. and Zeng, N.: A quasi-equilibrium tropical circulation model – formulation, J. Atmos. Sci., 57, 1741–1766, 2000. Neelin, J D., Zeng, N., Chou, C., Lin, J., Su, H., Munnich, M., Hales, K., and Meyerson, J.: The Neelin-Zeng Quasi-Equilibrium Tropical Circulation Model (QTCM1), Version 2.3, UCLA Department of Atmospheric Sciences, Los Angeles, http://www.atmos.ucla.edu/~csi/qtcm_man/v2.3/qtcm_manv2.3.pdf, 2002. Oliphant, T E.: Python for scientific computing, Comput. Sci. Eng., 9, 10–20, 2007. PCMDI: Climate Data Analysis Tools, http://cdat.sf.net, 2006. Pennington, N., Lee, A Y., and Rehder, B.: Cognitive activities and levels of abstraction in procedural and object-oriented design, Hum.-Comput. Interact., 10, 171–226, 1995. Peterson, P.: F2PY Users Guide and Reference Manual, http://cens.ioc.ee/projects/f2py2e/usersguide/index.html, 2005. PyCCSM: pyccsm: A Python version of the CCSM coupler, http://code.google.com/p/pyccsm/, 2008. Unidata: The NetCDF Tutorial, Boulder, CO, http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-tutorial.html, 2007. van~der Walt, S.: Documentation: NumPy and SciPy, http://www.scipy.org/Documentation, 2008. van Rossum, G.: Python Tutorial: Release 2.5.2, Python Software Foundation, http://www.python.org/doc/2.5.2/tut/tut.html, 2008. Zeng, N., Neelin, J D., Lau, K.-M., and Tucker, C J.: Enhancement of interdecadal climate variability in the Sahel by vegetation interaction, Science, 286, 1537–1540, 1999. Zeng, N., Neelin, J D., and Chou, C.: A quasi-equilibrium tropical circulation model–-implementation and simulation, J. Atmos. Sci., 57, 1767–1796, 2000.