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RTM McArtim 3.0

McArtim is an acronym for Monte Carlo Atmospheric Radiative Transfer Inversion Model. It is a RTM that has been designed to simulate the radiative transfer in the atmosphere of the Earth in the UV/vis/NIR spectral range with Monte Carlo methods. The method is described in detail in the McArtim paper. The aim is to support the analysis and evalution of scattered sun light measurements. Certain output quantities of the programs can be used in combination with the DOAS technique.

This webpage shall provide the necessary informations to use and run McArtim. It furthermore gives an overview on how the program results can be used in combination with numerical (inversion) methods to reconstruct parts of the atmospheric state from a spectroscopic measurement.

On January 8th 2015 I finished my PhD thesis on McArtim. The thesis can be downloaded here. The defense talk is here.

This is a screen video from the PathViewer program, which is used to view the output of the McArtim (Monte Carlo Art by Tim) radiative transport model. In order to see whether I can still do it, in response to a request I have just calculated a cloud scenario from NASA's i3rc phase 2 and looked at where a detector at about 22 km above the ground would measure a cumulus cloud field. The green points are scattering on cloud particles, red points are scattering on air molecules, yellow is scattering on the ground, blue are absorption events. The cloud layer is between 1 km and 2.4 km. The sun is almost at its zenith.

McArtim Specification

McArtim is an atmospheric radiative transfer code implementing the Monte Carlo method in order to solve the vector radiative transfer equation in the UV/vis/NIR spectral range. The RT model supports 1D and 3D, plane parallel and spherical model grids. The geographical model covers by default plane Lambertian surfaces, ocean BRDF, parametrized by wind speed and direction [Cox and Munk, 1954a, 1954b], and terrain modelling with lambertian surfaces. McArtim contains a Mie optical preprocessor [Mie, 1908, Wiscombe, 1979, Sanghavi, 2003] allowing for defining microphysical atmospheric spherical particle properties, i.e. complex refractive index and PSD, the famous model of Henyey and Greenstein [Henyey and Greenstein, 1941] besides arbitrarily definable differential scattering cross sections (phase functions), all in polarized form (Stokes matrices).

Polarized Scattering at air molecules is supported, as well as inelastic rotational Raman scattering [Placzek and Teller, 1933, Penney et al., 1974] to support modelling of the filling-in of Fraunhofer and other absorption lines [Grainger and Ring, 1962, Kattawar et al., 1981, Bussemer, 1993, M.Vountas et al., 1998]. Gaseous absorption is modelled by defining number densities and absorption cross sections. Absorption of gases with significant temperature and pressure dependence a line shape preprocessor [Humlı́c̆ek, 1982] is included compatible with the HITRAN database [Rothman, 2008]. The primarily modelled radiometric quantities are (ir)radiances, Ring effect affected (ir-)radiances, actinic fluxes, fluxes into and out of the grid layers and voxels and 1st and 2nd order derivates ot these radiometric quantities wrt to the optical and microphysical properties of the gaseous and particulate constituents of the atmosphere in order to support inverse modelling.

The modelled output of McArtims predecessor TRACY-II was validated against other radiation transport codes [Wagner et al, 2007] and irradiances obtained from balloon borne limb soundings [Deutschmann 2009]. In 2007 the code of TRACY-II was restructured yielding McArtim. Irradiances of McArtim occuring in the cloud scenes of the I3RC 3D radiation transport code intercomparison workshop [Cahalan et al., 2005] were validated [Deutschmann et al., 2011]. Polarized radiometric quantities, 2nd order derivates and the Ring effect were implemented and validated in comparison with other codes [Kokhanovsky et al., 2010, Deutschmann, 2015].

In the DOAS (Differential Optical Absorption Spectroscopy) community [Platt and Stutz 2008, ] McArtim is applied to model radiances in the spherically curved 1D atmosphere [Kritten, 2009], box air mass factors [Perliski and Solomon 1993, Puķı̄te et al., 2009], absorption spectra of volcanic plumes [Kern et al., 2012], amongst other applications.

References

Source Code

The source code of McArtim is available here. You must accept the licence conditions listed in the following when using the source code in any way.

McArtim Licence

*
*       You may not use the source code in ANY way for commercial purposes,
*       i.e. to generate profit from any derivations (modifications and/or compilations, etc.)
*       of the source code without my explicit permission. ANY commercial usage has to be allowed by me,
*       Tim Deutschmann, and will be charged with a profit share of at least 5%.
*
*       You may freely study, modify, compile and redistribute the following source code
*
*	                     FOR SCIENTIFIC PURPOSES ONLY.
*
*       The modified source code has to be made publically available at the latest on the day of
*       publishing the effects of the modification. All derivations of this source code shall remain
*       to be 'open source'.
*	
*       If you use the source code or the programs compiled from the original or
*       from the modified files you must properly cite the author of the original code by refering
*       to the following publications:
*	
*
*       Tim Deutschmann: Atmospheric Radiative Transfer Modelling with Monte Carlo Methods,
*       master thesis, University of Heidelberg, 2009.
*
*       Deutschmann, T., Beirle, S., Frieß, U., Grzegorski, M., Kern, C., Kritten, L.,
*       Platt, U., Prados-Román, C., Pukı̄te, J., Wagner, T., Werner, B., and Pfeilsticker, K.:
*       The Monte Carlo Atmospheric Radiative Transfer Model McArtim:
*       Introduction and Validation of Jacobians and 3D Features,
*       Journal of Quantitative Spectroscopy and Radiative Transfer, 112(6):1119-1137, 2011.
*
*       Tim Deutschmann: On Modeling Elastic and Inelastic Polarized Radiation Transport in the
*       Earth Atmosphere with Monte Carlo Methods, PhD thesis, University of Leipzig, 2014.
*
*       The official webpage of the McArtim source code 3.0 is
*
*                        http://www.tim-deutschmann.de/McArtim/index.html
*       
*       You may contact me through Tim.Deutschmann@posteo.de.
*
*       Have fun with the code!
*
*
*
*	                                                 Tim Deutschmann, Dossenheim, May 11th 2018.
	

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