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Example with SEVIRI data
------------------------
Let us try calculate the 3.9 micron reflectance for Meteosat-10:
.. doctest::
>>> sunz = 80.
>>> tb3 = 290.0
>>> tb4 = 282.0
>>> from pyspectral.near_infrared_reflectance import Calculator
>>> refl39 = Calculator('Meteosat-10', 'seviri', 'IR3.9')
>>> print('{refl:4.3f}'.format(refl=refl39.reflectance_from_tbs(sunz, tb3, tb4)[0]))
0.555
You can also provide the in-band solar flux from outside when calculating the
reflectance, saving a few milliseconds per call::
>>> from pyspectral.solar import (SolarIrradianceSpectrum, TOTAL_IRRADIANCE_SPECTRUM_2000ASTM)
>>> solar_irr = SolarIrradianceSpectrum(TOTAL_IRRADIANCE_SPECTRUM_2000ASTM, dlambda=0.0005)
>>> from pyspectral.rsr_reader import RelativeSpectralResponse
>>> seviri = RelativeSpectralResponse('Meteosat-10', 'seviri')
>>> sflux = solar_irr.inband_solarflux(seviri.rsr['IR3.9'])
>>> refl39 = Calculator('Meteosat-10', 'seviri', 'IR3.9', solar_flux=sflux)
>>> print('{refl:4.3f}'.format(refl=refl39.reflectance_from_tbs(sunz, tb3, tb4)[0]))
0.555
By default the data are masked outside the default Sun zenith-angle (SZA) correction limit (85.0 degrees).
The masking can be adjusted via `masking_limit` keyword argument to `Calculator`, and turned of by
defining `Calculator(..., masking_limit=None)`. The SZA limit can be adjusted via `sunz_threshold` keyword argument:
`Calculator(..., sunz_threshold=88.0)`.
Integration with SatPy
^^^^^^^^^^^^^^^^^^^^^^
The SatPy_ package integrates PySpectral_ so that it is very easy with only a
very few lines of code to make RGB images with the 3.9 reflectance as one of
the bands. Head to the `PyTroll gallery`_ pages for examples. SatPy_ for instance
has a *snow* RGB using the 0.8 micron, the 1.6 micron and the 3.9 micron
reflectance derived using PySpectral_.
.. _PySpectral: http://github.com/pytroll/pyspectral
.. _SatPy: http://www.github.com/pytroll/satpy
.. _PyOrbital: http://www.github.com/pytroll/pyorbital
.. _`PyTroll gallery`: http://pytroll.github.io/gallery.html
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