HELIOS-K: AN ULTRAFAST, OPEN-SOURCE OPACITY CALCULATOR FOR RADIATIVE TRANSFER

被引:138
作者
Grimm, Simon L. [1 ]
Heng, Kevin [2 ]
机构
[1] Univ Zurich, Inst Computat Sci, Winterthurerstr 190, CH-8057 Zurich, Switzerland
[2] Univ Bern, Inst Phys, Ctr Space & Habitabil, CH-3012 Bern, Switzerland
基金
瑞士国家科学基金会;
关键词
methods: numerical; planets and satellites: atmospheres; radiative transfer; ATMOSPHERIC RETRIEVAL; TRANSMISSION SPECTRA; BROWN DWARF; TEMPERATURE; CIRCULATION; MODELS;
D O I
10.1088/0004-637X/808/2/182
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present an ultrafast opacity calculator that we name HELIOS-K. It takes a line list as an input, computes the shape of each spectral line, and provides an option for grouping an enormous number of lines into a manageable number of bins. We implement a combination of Algorithm 916 and Gauss-Hermite quadrature to compute the Voigt profile, write the code in CUDA, and optimize the computation for graphics processing units (GPUs). We restate the theory of the k-distribution method and use it to reduce similar to 10(5)-10(8) lines to similar to 10-10(4) wavenumber bins, which may then be used for radiative transfer, atmospheric retrieval and general circulation models. The choice of line-wing cutoff for the Voigt profile is a significant source of error and affects the value of the computed flux by similar to 10%. This is an outstanding physical (rather than computational) problem, due to our incomplete knowledge of pressure broadening of spectral lines in the far line wings. We emphasize that this problem remains regardless of whether one performs line-by-line calculations or uses the k-distribution method and affects all calculations of exoplanetary atmospheres requiring the use of wavelength-dependent opacities. We elucidate the correlated-k approximation and demonstrate that it applies equally to inhomogeneous atmospheres with a single atomic/molecular species or homogeneous atmospheres with multiple species. Using a NVIDIA K20 GPU, HELIOS-K is capable of computing an opacity function with similar to 10(5) spectral lines in similar to 1 s and is publicly available as part of the Exoclimes Simulation Platform (www.exoclime.org).
引用
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页数:9
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共 36 条
[31]   HITEMP, the high-temperature molecular spectroscopic database [J].
Rothman, L. S. ;
Gordon, I. E. ;
Barber, R. J. ;
Dothe, H. ;
Gamache, R. R. ;
Goldman, A. ;
Perevalov, V. I. ;
Tashkun, S. A. ;
Tennyson, J. .
JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER, 2010, 111 (15) :2139-2150
[32]   The HITRAN molecular spectroscopic database and HAWKS (HITRAN Atmospheric Workstation): 1996 edition [J].
Rothman, LS ;
Rinsland, CP ;
Goldman, A ;
Massie, ST ;
Edwards, DP ;
Flaud, JM ;
Perrin, A ;
Camy-Peyret, C ;
Dana, V ;
Mandin, JY ;
Schroeder, J ;
McCann, A ;
Gamache, RR ;
Wattson, RB ;
Yoshino, K ;
Chance, KV ;
Jucks, KW ;
Brown, LR ;
Nemtchinov, V ;
Varanasi, P .
JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER, 1998, 60 (05) :665-710
[33]   Exoplanet Atmospheres [J].
Seager, Sara ;
Deming, Drake .
ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS, VOL 48, 2010, 48 :631-672
[34]   Atomic and molecular opacities for brown dwarf and giant planet atmospheres [J].
Sharp, C. M. ;
Burrows, A. .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 2007, 168 (01) :140-166
[35]   ATMOSPHERIC CIRCULATION OF HOT JUPITERS: COUPLED RADIATIVE-DYNAMICAL GENERAL CIRCULATION MODEL SIMULATIONS OF HD 189733b and HD 209458b [J].
Showman, Adam P. ;
Fortney, Jonathan J. ;
Lian, Yuan ;
Marley, Mark S. ;
Freedman, Richard S. ;
Knutson, Heather A. ;
Charbonneau, David .
ASTROPHYSICAL JOURNAL, 2009, 699 (01) :564-584
[36]   Algorithm 916: Computing the Faddeyeva and Voigt Functions [J].
Zaghloul, Mofreh R. ;
Ali, Ahmed N. .
ACM TRANSACTIONS ON MATHEMATICAL SOFTWARE, 2011, 38 (02)