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Working with HITRAN database using HAPI: HITRAN Application Programming Interface Roman V. Kochanova,c, Christian Hilla,b, Piotr Wcisloa,d, Jonas S. Wilzewskie, Iouli E. Gordona, and Laurence S. Rothmana aHarvard-Smithsonian Center for Astrophysics, Cambridge MA, USA bUniversity cTomsk dNicolas eHarvard College London, London, UK State University, Tomsk, RUSSIA Copernicus University, Torun, POLAND University, Astronomy Dept, Cambridge MA, USA Introduction ● What is API? ● API, an abbreviation of Application Programming Interface, is a set of routines, protocols, and tools for building software applications. The API specifies how software components should interact and be used in a program code. – A good API makes it easier to develop a program by providing all the building blocks. A programmer then puts the blocks together. What is HITRAN API (HAPI)? – – – – Python module (library of functions) to work with HITRAN data Main purpose: extending user's code by the data of HITRAN and functionality of HITRANonline Offline part of HITRANonline functionality Why is API a powerful tool for creating radiative-transfer codes? ● Seamless data format conversion Parsing data (cross-sections, line-by-line, parameters) “in a background” – ● Flexibility – – – ● ● Large number of input parameters to control calculation Possibility to add custom user code Possibility to use different line parameters and compare results Portability Access to external libraries – Python, Fortran, C++ ... What is HAPI for? ● ● ● ● Retrieve and use of HITRANonline data (line lists, cross sections, molecule and isotopologue info...) from a program written in Python (HITRANonline data is parsed automatically) Reduce the load of HITRANonline web service (calculation of cross sections can be resource-demanding!) Give more flexibility in data filtering (as in RDB) Provide a possibility to work with HITRAN data “offline” (locally) Prerequisites 1) Python 2.6+: https://www.python.org/ 2) Numpy: http://www.numpy.org/ License: open source => Scientific Python distribution (“Sage”, “Anaconda” or any other similar distribution) Download http://hitran.org/hapi - + Python code - + User guide Zenodo community (DOI for referencing): https://zenodo.org/collection/user-hapi How to use HAPI? ● Ways of usage: – In interactive Python shell – In a program (script) as a normal library Jupyter/IPython – How to use HAPI? ● Ways of usage: – In interactive Python shell – In a program (script) as a normal library Jupyter/IPython – ● Where to use? – Local machine – Remote server (cluster, ssh access) – Cloud service (Wakari, PythonAnywhere, etc…) HAPI architecture USER Python API PLAIN TEXT XML HDF5 DATABASE DATABASE DATABASE LOCAL HAPI architecture USER Python API PLAIN TEXT XML HDF5 DATABASE DATABASE DATABASE API functions: → absorptionCoefficient_HT(…) → partitionSum(…) → select(…) → describeTable ( … ) →… LOCAL HAPI architecture USER Python API PLAIN TEXT XML HDF5 DATABASE DATABASE DATABASE API functions: → absorptionCoefficient_HT(…) → partitionSum(…) → select(…) → describeTable ( … ) →… LOCAL REMOTE HAPI architecture USER Python API PLAIN TEXT XML HDF5 DATABASE DATABASE DATABASE API functions: → absorptionCoefficient_HT(…) → partitionSum(…) → select(…) → describeTable ( … ) →… LOCAL REMOTE Features (1) ● ● ● ● Fetching data (HITRANonline => local machine) Filtering and processing the data in SQL-like fashion Access to conventional Python structures (lists, tuples, dictionaries) for representing spectroscopic data. Accounting for “non-standard” HITRAN parameters: speed dependence, Dicke narrowing, different broadeners etc… Features (2) ● ● ● Total internal partition sum (TIPS-2011): R. Gamache et al. Icarus 215 (2011) 391–400 – Included information about 51 isotopologues – 70-3000K temperature range pCqSDHC line profile: Ngo et al. JQSRT 129 (2013) 89–100 (“Partially Correlated Quadratic Speed dependent Hard Collision Profile”) – a.k.a. Hartmann-Tran profile (HTP) – Can be reduced to VP, RP, qSDVP, qSDRP Codes are rewritten in Python using Numpy library (fast array operations) Features (3) ● ● ● High-resolution spectra simulation accounting for pressure, temperature and optical path length. The following spectral functions can be calculated: – absorption coefficient – absorption spectrum – transmittance spectrum – radiance spectrum Spectral calculation using a number of instrumental functions to simulate experimental spectra. Possibility to extend the API's functionality by adding custom line profiles, partition sums and instrumental functions. Features (4) ● Embedded documentation (getHelp) Data manipulation ● Similar to SQL (for single table queries) ● Spectroscopic parameters are stored in tables ● Display data (~ SQL’s select) ● Apply filtering conditions (accounting wide range of expressions on parameters, including regexps) ● Adding/removing custom parameters ● Group by parameter/expression Ipython: Cross section showcase - Download data M I Range Ipython: Cross section showcase - Filter data Ipython: Cross section showcase - Cross-section calculation Ipython: Cross section showcase - Plotting result Comment on “Radiative forcings for 28 potential Archean greenhouse gases” Clim. Past 10, 1779 (2014) Comment on “Radiative forcings for 28 potential Archean greenhouse gases” Clim. Past 10, 1779 (2014) Plans ● More data formats (XML, JSON, NetCDF …) ● More profiles (soft collisions, line mixing) ● ● ● New data storage format (less bulky, more efficient) Update partition sums (TIPS-2013) Add functions for dealing with HITRAN’s collision-induced absorption cross-sections Acknowledgements CfA HITRAN team: Iouli Gordon, Laurence Rothman, Christian Hill, Jonas Wilzewski, Piotr Wcisło NASA Grants: PASCAL, AURA Newsletter, bug reports, feedback … ● It’s still work in progress! ● Please ask your questions ● Report bugs [email protected] … and thanks for your attention!