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Commit 9a120dd

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mikofskiwholmgren
mikofski
authored and
wholmgren
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add linke turbidity formulas module to atmosphere (#278)
* add linke turbidity formulas module * add kasten 1996 pyrheliometric formula for linke turbidity factor * move atmosphere into package, just for fun, why not? * make __init__ with same api as before Signed-off-by: Mark Mikofski <mark.mikofski@sunpowercorp.com> * ignore venv, sublime * revert api changes from 6e9aaf0 * append linke_turb_forms.py to atmosphere.py * rm -rf atmosphere/ Signed-off-by: Mark Mikofski <mark.mikofski@sunpowercorp.com> * move demo to tests * import xrange from six for python 3 compatibility * fix pyrheliometric formula is from 1980 * fix docstring * just use `range` instead of importing `six` * change function to `kasten80_lt` to match `gueymard94_pw` * start adding references * test kaste96_lt against linke turbidity using tmy3 at 700nm * add lots of references * cite text quoted directly from Ineichen * acknowledge Armel * fix docstrings for numpydocs * removing filters from kasten pyrhelometric formula * refactor kasten96_lt api simpler * remove alpha argument * update docstring to explain that if molineaux method, then aod is shape is only aod at 700[nm] but if bird-hulstrom, then aod should be both aod380 and aod500 * add see also to angstrom_aod_at_lambda * add warning for air mass or pwat out of range * check for bird-hulstrom, raise type error if neither molineaux nor * also simplify angstrom_aod_at_lambda() api, change aod to aod0, change lambda0 to lambda1, and add lambda0, update docstring * update test_atmosphere.test_kasten96_lt with new changes * add angstrom_alpha() method in atmosphere to calculate alpha * simplify kasten96_lt API * separate arguments so their shapes don't change depending on method, ie: before aod could be 1, 2, N, N x 1 or N x 2 depending on whether Molineaux or Bird-Hulstrom were used, now, there are 3 separate args, aod700, aod380 and aod500. * fix misspelling of Hulstrom, no "d", note several sources also make this error :( * add new methods to api.rst * add test_angstrom tests * add raises value error test for bad method * add lower() to compare only lower case of method name * add new linke and angstrom functions to api.rst * fix more hulstrom errors, no "d" * fix typos in referecnes * add doi to sphinx docs as extlink * add 'doi': ('http://dx/doi.org/%s', 'DOI: ') to extlink in conf.py * change doi links everywhere to use :doi:`doi number` instead of links * make landscape happy and use r"""docstring with :math:`\alpha`""" * instead of """docstring with :math:`\\alpha` * add Co-Action publishing for original Tellus A DOI before moving to Taylor & Francis * reformat long lines to make landscape happy :) * use broadband AOD arg instead of methods * change kasten96_lt AOD args to just a single arg called aod_bb for broadband AOD * remove "method" arg and if-then-else on method.lower() in kasten96_lt() * add note that according to Molineaux, aod at 700 nm is a good approximation for broadband aod * add new function bird_hulstrom80_aod_bb to atmosphere.py * add it to api.rst * add new test for bird_hulstrom80_aod_bb() to test_atmosphere.py * update test_kasten96_lt() to use aod_bb * use verbose names: - s/am/airmass_absolute/g - s/pwat/precipitable_water/g * fix angstrom aod test to use more realistic values * don't use brackets around units * remove test for raises ValueError in test_kasten * use hard coded test values instead of TMY3 * values span pwat range 0 - 5 cm, and airmass between 1 & 2.5 atm * remove tmy3 file * don't try Bird-Hulstrom, not necessary * make pylint happy, isclose(a, b) a & b should be array or iterable * remove unused imports * fix test kasten * fix assert np.isclose() should be scalar only * super simplify test_kasten96_lt() to ranges of inputs and expected outputs, don't need to compare to actual data, just test that method is working nominally * remove clearsky import from test_atmosphere * add missing assert statements for tests * update hulstrom expected value * remove old melbourne-fl test data
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‎.gitignore

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Drafts/
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*/build/
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build/
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venv/
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*.egg-info/
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.installed.cfg
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.pydevproject
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.spyderproject
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.idea/
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*.sublime-project
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*.sublime-workspace
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# Rope
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.ropeproject

‎docs/sphinx/source/api.rst

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atmosphere.alt2pres
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atmosphere.gueymard94_pw
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atmosphere.first_solar_spectral_correction
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atmosphere.bird_hulstrom80_aod_bb
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atmosphere.kasten96_lt
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atmosphere.angstrom_aod_at_lambda
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atmosphere.angstrom_alpha
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Irradiance

‎docs/sphinx/source/conf.py

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extlinks = {'issue': ('https://github.com/pvlib/pvlib-python/issues/%s',
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'GH'),
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'wiki': ('https://github.com/pvlib/pvlib-python/wiki/%s',
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'wiki ')}
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'wiki '),
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'doi': ('http://dx.doi.org/%s', 'DOI: ')}
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# -- Options for manual page output ---------------------------------------
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‎docs/sphinx/source/whatsnew/v0.4.4.txt

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Enhancements
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~~~~~~~~~~~~
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* Added Kasten pyrheliometric formula to calculate Linke turbidity factors with
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improvements by Ineichen and Perez to extend range of air mass (:issue:`278`)
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Documentation
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~~~~~~~~~~~~~
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~~~~~~~~~~~~
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* Will Holmgren
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* Mark Mikofski

‎pvlib/atmosphere.py

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@@ -292,7 +292,7 @@ def gueymard94_pw(temp_air, relative_humidity):
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----------
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.. [1] W. M. Keogh and A. W. Blakers, Accurate Measurement, Using Natural
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Sunlight, of Silicon Solar Cells, Prog. in Photovoltaics: Res.
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and Appl. 2004, vol 12, pp. 1-19 (DOI: 10.1002/pip.517)
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and Appl. 2004, vol 12, pp. 1-19 (:doi:`10.1002/pip.517`)
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.. [2] C. Gueymard, Analysis of Monthly Average Atmospheric Precipitable
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Water and Turbidity in Canada and Northern United States,
@@ -467,3 +467,193 @@ def first_solar_spectral_correction(pw, airmass_absolute, module_type=None,
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coeff[4]*np.sqrt(pw) + coeff[5]*ama/np.sqrt(pw))
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return modifier
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def bird_hulstrom80_aod_bb(aod380, aod500):
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"""
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Approximate broadband aerosol optical depth.
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Bird and Hulstrom developed a correlation for broadband aerosol optical
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depth (AOD) using two wavelengths, 380 nm and 500 nm.
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Parameters
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----------
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aod380 : numeric
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AOD measured at 380 nm
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aod500 : numeric
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AOD measured at 500 nm
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Returns
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-------
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aod_bb : numeric
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broadband AOD
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See also
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--------
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kasten96_lt
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References
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----------
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[1] Bird and Hulstrom, "Direct Insolation Models" (1980)
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`SERI/TR-335-344 <http://www.nrel.gov/docs/legosti/old/344.pdf>`_
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[2] R. E. Bird and R. L. Hulstrom, "Review, Evaluation, and Improvement of
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Direct Irradiance Models", Journal of Solar Energy Engineering 103(3),
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pp. 182-192 (1981)
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:doi:`10.1115/1.3266239`
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"""
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# approximate broadband AOD using (Bird-Hulstrom 1980)
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return 0.27583 * aod380 + 0.35 * aod500
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def kasten96_lt(airmass_absolute, precipitable_water, aod_bb):
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"""
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Calculate Linke turbidity factor using Kasten pyrheliometric formula.
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Note that broadband aerosol optical depth (AOD) can be approximated by AOD
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measured at 700 nm according to Molineaux [4] . Bird and Hulstrom offer an
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alternate approximation using AOD measured at 380 nm and 500 nm.
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Based on original implementation by Armel Oumbe.
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.. warning::
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These calculations are only valid for air mass less than 5 atm and
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precipitable water less than 5 cm.
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Parameters
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----------
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airmass_absolute : numeric
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airmass, pressure corrected in atmospheres
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precipitable_water : numeric
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precipitable water or total column water vapor in centimeters
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aod_bb : numeric
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broadband AOD
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Returns
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-------
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lt : numeric
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Linke turbidity
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See also
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--------
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bird_hulstrom80_aod_bb
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angstrom_aod_at_lambda
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References
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----------
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[1] F. Linke, "Transmissions-Koeffizient und Trubungsfaktor", Beitrage
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zur Physik der Atmosphare, Vol 10, pp. 91-103 (1922)
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[2] F. Kasten, "A simple parameterization of the pyrheliometric formula for
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determining the Linke turbidity factor", Meteorologische Rundschau 33,
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pp. 124-127 (1980)
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[3] Kasten, "The Linke turbidity factor based on improved values of the
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integral Rayleigh optical thickness", Solar Energy, Vol. 56, No. 3,
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pp. 239-244 (1996)
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:doi:`10.1016/0038-092X(95)00114-7`
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[4] B. Molineaux, P. Ineichen, N. O'Neill, "Equivalence of pyrheliometric
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and monochromatic aerosol optical depths at a single key wavelength",
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Applied Optics Vol. 37, issue 10, 7008-7018 (1998)
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:doi:`10.1364/AO.37.007008`
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[5] P. Ineichen, "Conversion function between the Linke turbidity and the
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atmospheric water vapor and aerosol content", Solar Energy 82,
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pp. 1095-1097 (2008)
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:doi:`10.1016/j.solener.2008.04.010`
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[6] P. Ineichen and R. Perez, "A new airmass independent formulation for
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the Linke Turbidity coefficient", Solar Energy, Vol. 73, no. 3, pp. 151-157
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(2002)
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:doi:`10.1016/S0038-092X(02)00045-2`
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"""
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# "From numerically integrated spectral simulations done with Modtran
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# (Berk, 1989), Molineaux (1998) obtained for the broadband optical depth
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# of a clean and dry atmospshere (fictitious atmosphere that comprises only
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# the effects of Rayleigh scattering and absorption by the atmosphere gases
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# other than the water vapor) the following expression"
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# - P. Ineichen (2008)
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delta_cda = -0.101 + 0.235 * airmass_absolute ** (-0.16)
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# "and the broadband water vapor optical depth where pwat is the integrated
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# precipitable water vapor content of the atmosphere expressed in cm and am
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# the optical air mass. The precision of these fits is better than 1% when
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# compared with Modtran simulations in the range 1 < am < 5 and
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# 0 < pwat < 5 cm at sea level" - P. Ineichen (2008)
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delta_w = 0.112 * airmass_absolute ** (-0.55) * precipitable_water ** 0.34
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# broadband AOD
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delta_a = aod_bb
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# "Then using the Kasten pyrheliometric formula (1980, 1996), the Linke
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# turbidity at am = 2 can be written. The extension of the Linke turbidity
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# coefficient to other values of air mass was published by Ineichen and
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# Perez (2002)" - P. Ineichen (2008)
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lt = -(9.4 + 0.9 * airmass_absolute) * np.log(
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np.exp(-airmass_absolute * (delta_cda + delta_w + delta_a))
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) / airmass_absolute
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# filter out of extrapolated values
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return lt
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def angstrom_aod_at_lambda(aod0, lambda0, alpha, lambda1=700.0):
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r"""
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Get AOD at specified wavelength using Angstrom turbidity model.
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Parameters
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----------
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aod0 : numeric
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aerosol optical depth (AOD) measured at known wavelength
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lambda0 : numeric
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wavelength in nanometers corresponding to ``aod0``
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alpha : numeric
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Angstrom :math:`\alpha` exponent corresponding to ``aod0``
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lambda1 : numeric
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desired wavelength in nanometers, defaults to 700 nm
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Returns
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-------
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aod1 : numeric
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AOD at desired wavelength, ``lambda1``
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See also
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--------
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angstrom_alpha
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References
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----------
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[1] Anders Angstrom, "On the Atmospheric Transmission of Sun Radiation and
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On Dust in the Air", Geografiska Annaler Vol. 11, pp. 156-166 (1929) JSTOR
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:doi:`10.2307/519399`
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[2] Anders Angstrom, "Techniques of Determining the Turbidity of the
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Atmosphere", Tellus 13:2, pp. 214-223 (1961) Taylor & Francis
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:doi:`10.3402/tellusa.v13i2.9493` and Co-Action Publishing
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:doi:`10.1111/j.2153-3490.1961.tb00078.x`
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"""
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return aod0 * ((lambda1 / lambda0) ** (-alpha))
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def angstrom_alpha(aod1, lambda1, aod2, lambda2):
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r"""
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Calculate Angstrom alpha exponent.
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Parameters
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----------
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aod1 : numeric
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first aerosol optical depth
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lambda1 : numeric
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wavelength in nanometers corresponding to ``aod1``
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aod2 : numeric
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second aerosol optical depth
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lambda2 : numeric
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wavelength in nanometers corresponding to ``aod2``
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Returns
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-------
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alpha : numeric
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Angstrom :math:`\alpha` exponent for AOD in ``(lambda1, lambda2)``
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See also
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--------
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angstrom_aod_at_lambda
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"""
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return - np.log(aod1 / aod2) / np.log(lambda1 / lambda2)

‎pvlib/test/test_atmosphere.py

Copy file name to clipboardExpand all lines: pvlib/test/test_atmosphere.py
+41-4Lines changed: 41 additions & 4 deletions
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@@ -1,4 +1,3 @@
1-
import datetime
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import itertools
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import numpy as np
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import pytest
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from numpy.testing import assert_allclose
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from pvlib.location import Location
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from pvlib import solarposition
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from pvlib import atmosphere
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from pvlib import solarposition
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latitude, longitude, tz, altitude = 32.2, -111, 'US/Arizona', 700
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def test_first_solar_spectral_correction_ambiguous():
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with pytest.raises(TypeError):
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atmosphere.first_solar_spectral_correction(1, 1)
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def test_kasten96_lt():
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"""Test Linke turbidity factor calculated from AOD, Pwat and AM"""
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amp = np.array([1, 3, 5])
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pwat = np.array([0, 2.5, 5])
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aod_bb = np.array([0, 0.1, 1])
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lt_expected = np.array(
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[[[1.3802, 2.4102, 11.6802],
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[1.16303976, 2.37303976, 13.26303976],
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[1.12101907, 2.51101907, 15.02101907]],
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[[2.95546945, 3.98546945, 13.25546945],
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[2.17435443, 3.38435443, 14.27435443],
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[1.99821967, 3.38821967, 15.89821967]],
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[[3.37410769, 4.40410769, 13.67410769],
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[2.44311797, 3.65311797, 14.54311797],
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[2.23134152, 3.62134152, 16.13134152]]]
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)
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lt = atmosphere.kasten96_lt(*np.meshgrid(amp, pwat, aod_bb))
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assert np.allclose(lt, lt_expected, 1e-3)
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return lt
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def test_angstrom_aod():
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"""Test Angstrom turbidity model functions."""
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aod550 = 0.15
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aod1240 = 0.05
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alpha = atmosphere.angstrom_alpha(aod550, 550, aod1240, 1240)
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assert np.isclose(alpha, 1.3513924317859232)
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aod700 = atmosphere.angstrom_aod_at_lambda(aod550, 550, alpha)
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assert np.isclose(aod700, 0.10828110997681031)
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def test_bird_hulstrom80_aod_bb():
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"""Test Bird_Hulstrom broadband AOD."""
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aod380, aod500 = 0.22072480948195175, 0.1614279181106312
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bird_hulstrom = atmosphere.bird_hulstrom80_aod_bb(aod380, aod500)
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assert np.isclose(0.11738229553812768, bird_hulstrom)

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