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# Copyright (c) 2020 Stefan Bender |
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# |
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# This file is part of pyeppaurora. |
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# pyeppaurora is free software: you can redistribute it or modify |
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# it under the terms of the GNU General Public License as published |
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# by the Free Software Foundation, version 2. |
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# See accompanying LICENSE file or http://www.gnu.org/licenses/gpl-2.0.html. |
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"""Atmospheric ionization rate parametrizations |
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From the SSUSI ATBD documents [#]_ [#]_ [#]_. |
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.. [#] https://ssusi.jhuapl.edu/data_algorithms |
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.. [#] https://ssusi.jhuapl.edu/docs/algorithms/Aurora_LID_c_Version_2.0.pdf |
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.. [#] https://ssusi.jhuapl.edu/docs/algorithms/SSUSI_DataProductAlgorithms_V1_13.doc |
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""" |
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import numpy as np |
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__all__ = ["ssusi_ioniz"] |
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# pre-determined analytical model coefficients of peak auroral ionization production rate height |
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# electrons |
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CHMAX_E = [2.07923, -9.41205e-2] |
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# protons |
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CHMAX_P = [2.078, -4.072e-2] |
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# pre-determined analytical model coefficients of peak auroral ionization production rate |
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# electrons |
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CPMAX_E = [0., 9.25777e-1, -5.03201e-1] |
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# protons |
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CPMAX_P = [0., 3.50766e-1, -8.84737e-2] |
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def ssusi_ioniz(z, en, flux, chmax=CHMAX_E, cpmax=CPMAX_E, eref=1., pref=2.57e3, shpc=1.427e10): |
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"""Parametrization from Sect. 2.6.2 in [#]_ |
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Parameters |
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---------- |
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z: float, array_like |
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en: float, array_like |
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flux: float, array_like |
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Energy flux in [erg cm^{-2} s^{-1}], note: **not** keV. |
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chmax: tuple, list, (2,) optional |
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Pre-determined analytical model coefficients of peak auroral ionization production rate height. |
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cpmax: tuple, list, (3,) optional |
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Pre-determined analytical model coefficients of peak auroral ionization production rate |
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Returns |
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------- |
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q: float, array_like |
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The atmospheric ionization rate at altitude z. |
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References |
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---------- |
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.. [#] https://ssusi.jhuapl.edu/docs/algorithms/Aurora_LID_c_Version_2.0.pdf |
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""" |
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# pre-determined scale height proportionality factor |
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shpf = 1e-5 / np.exp(1.) |
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# log10 ratio of the characteristic energy (Sect. 2.6.2.2, 2.6.2.4) |
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l10rce = np.log10(en / eref) |
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# peak auroral ionization production rate height (Sect. 2.6.2.6) |
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tempX = np.polyval(chmax[::-1], l10rce) |
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pprh = 10**tempX |
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# peak auroral ionization production rate (Sect. 2.6.2.8) |
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tempX = np.polyval(cpmax[::-1], l10rce) |
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ppr1 = 10**(tempX) * pref |
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# scale height of the auroral ionization production rate (Sect. 2.6.2.10) |
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shpr = shpf * shpc / ppr1 |
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# electron peak auroral ionization production rate (Sect. 2.6.2.12) |
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pprq = flux * ppr1 |
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# ionization production rate altitude profile (Sect. 2.6.2.15) |
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rhpr = (z - pprh) / shpr |
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q = pprq * np.exp(1. - rhpr - np.exp(-rhpr)) |
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return q |
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st-bender /
pyeppaurora
