JURASSIC

JURASSIC (Juelich Rapid Spectral Simulation Code) is a radiative transfer model for simulating infrared radiation in the Earth's atmosphere. It combines efficient radiative transfer approximations, precomputed spectroscopic lookup tables, and retrieval tools for the analysis of atmospheric remote sensing measurements.

Infrared limb, nadir, and zenith observations are widely used to study atmospheric temperature, composition, and dynamical variability. Their interpretation requires radiative transfer calculations, but computationally expensive line-by-line models can become a limiting factor when processing large satellite datasets, performing sensitivity studies, or carrying out iterative retrievals.

JURASSIC addresses this need by combining fast radiative transfer approximations with precomputed spectroscopic lookup tables. The model is designed for applications requiring large numbers of infrared radiance or transmittance calculations with configurable atmospheric states, instrument characteristics, spectral channels, and observation geometries.

JURASSIC has been applied to satellite remote sensing and atmospheric research, including temperature and trace-gas retrievals and studies of atmospheric gravity waves. Its efficient implementation and parallelisation make it suitable for applications ranging from individual workstation calculations to large-scale processing on high-performance computing systems.

Features

• Efficient infrared radiative transfer: JURASSIC implements the Emissivity Growth Approximation (EGA) and the Curtis–Godson Approximation (CGA) for fast calculations of atmospheric radiances and transmittances.
• Lookup-table spectroscopy: Band transmittances are obtained from precomputed spectroscopic lookup tables based on detailed line-by-line calculations, substantially reducing the computational cost of repeated radiative transfer simulations.
• Multiple observation geometries: Limb, nadir, and zenith viewing geometries are supported, enabling applications to a range of satellite, airborne, and ground-based remote sensing measurements.
• Optimal-estimation retrievals: JURASSIC provides an optimal-estimation retrieval framework for inverse modelling of atmospheric state variables such as temperature and trace-gas volume mixing ratios.
• Flexible configuration: Spectral channels, instrument configurations, atmospheric profiles, and observation geometries can be adapted to different instruments and scientific applications.
• Validated radiative transfer: JURASSIC has been evaluated in published intercomparisons with established radiative transfer models including the Karlsruhe Optimized and Precise Radiative Transfer Algorithm (KOPRA), the Reference Forward Model (RFM), and the Stand-alone AIRS Radiative Transfer Algorithm (SARTA).
• High-performance computing: OpenMP parallelisation across the tool suite and MPI-based task distribution for retrieval workloads enable efficient processing of large datasets on multicore and HPC systems.
• Reproducible workflows and testing: Example applications for limb, nadir, and zenith observations, reference results, and regression tests support verification of installations and reproducible model development.
• Scientific data and documentation: Precomputed spectroscopic lookup-table datasets, user and developer documentation, and versioned software releases are publicly available.
• Open-source development: JURASSIC is distributed under the GNU General Public License (GPL) and is developed openly on GitHub.

Getting started

JURASSIC is available from the GitHub repository:

https://github.com/slcs-jsc/jurassic

The repository contains installation instructions, example applications, regression tests, and information on required and optional software dependencies.

More detailed information for users and developers is provided in the JURASSIC manual:

https://slcs-jsc.github.io/jurassic/

Precomputed spectroscopic lookup tables for common configurations are available from the JURASSIC data repository:

https://datapub.fz-juelich.de/slcs/jurassic/

Example simulations are provided for limb, nadir, and zenith observation geometries and can be used to verify an installation and explore typical JURASSIC workflows.

Further information

The following publications provide background on JURASSIC and its applications:

• Baumeister, P. F. and Hoffmann, L.: Fast infrared radiative transfer calculations using graphics processing units: JURASSIC-GPU v2.0, Geoscientific Model Development, 15, 1855–1874, https://doi.org/10.5194/gmd-15-1855-2022, 2022.

• Hoffmann, L. and Alexander, M. J.: Retrieval of stratospheric temperatures from Atmospheric Infrared Sounder radiance measurements for gravity wave studies, Journal of Geophysical Research: Atmospheres, 114, D07105, https://doi.org/10.1029/2008JD011241, 2009.

• Hoffmann, L., Kaufmann, M., Spang, R., Müller, R., Remedios, J. J., Moore, D. P., Volk, C. M., von Clarmann, T., and Riese, M.: Envisat MIPAS measurements of CFC-11: retrieval, validation, and climatology, Atmospheric Chemistry and Physics, 8, 3671–3688, https://doi.org/10.5194/acp-8-3671-2008, 2008.

The source code and individual software releases can be cited using the JURASSIC Zenodo record:

https://doi.org/10.5281/zenodo.4572889

Further citation information is available in the CITATION.cff file in the GitHub repository.

Contributing

Contributions and collaborations are welcome. JURASSIC is intended for use in both research and operational remote sensing applications, and we welcome feedback, feature requests, bug reports, and contributions from users and developers.

Contribution guidelines and the project Code of Conduct are available in the GitHub repository. Questions about scientific applications or technical aspects of JURASSIC can also be addressed directly to the development team.

Contact

Dr. Lars Hoffmann
Jülich Supercomputing Centre
Forschungszentrum Jülich
l.hoffmann@fz-juelich.de