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100 lines
3.8 KiB
Markdown
100 lines
3.8 KiB
Markdown
**Note:**
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A manuscript of this atmospheric code is in preparation and will be submitted to the Monthly Notices of the Royal Astronomical Society (MNRAS) journal before the end of the year (2019).
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If you use this code for your project, please acknowledge this by making a reference to this paper in due course. You can contact me, the author, for the submission and review status.
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Author info: *Joost van den Born*, *born@astron.nl*
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*Below you can find a set of models describing the atmospheric refraction and dispersion.*
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**Contents:**
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- atmosphericModel : Python model that can be used to calculate the atmospheric refraction and dispersion, the main content of this repository.
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- refractionModel.py : Python script that compares the output of the different refraction models.
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Can be used as an example on how to use atmosphericModel.py
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- atmospheric refraction example: jupyter notebook example
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**On the contents of the atmosphericModel package**
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The package contains the following files:
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- 1976USSA.txt : Data file of the 1976 US Standard Atmosphere.
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- ciddorModel.py : Contains the `Observatory()` class to calculate the refractive index of atmospheric air, using the Ciddor (1996) model.
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- dispersionModels.py : Contains various atmospheric models that can be used to calculate the atmospheric dispersion
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- examples.py : Contains several quick functions, e.g. to quickly calculate the refractive index.
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- refractionModels.py : Contains various atmospheric models that can be used to calculate the atmospheric refraction
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- refractivityModels.py : Contains various functions from literature to calculate the refractive index. Some examples of works included are Ciddor (1996), Barrell & Sears (1939), SLALIB, Owens (1967) and Edlen (1966).
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**On the dispersion model:**
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Dispersion model from Ciddor, 1996, calculates the index of refraction of air using the following parameters:
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- Temperature
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- Pressure
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- Relative humidity
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- CO2 density
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**On the atmospheric refraction / atmospheric dispersion models:**
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Available models:
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- Full integration using the refractive integral (requires detailed information about the atmosphere, e.g. 1976USSA.txt)
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- Plane-parallel atmosphere refraction model
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- Cassini's homogeneous atmosphere refraction model
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- Oriani's theorem ( Atan(z) + Btan^3(z) )
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- Oriani's theorem expanded ( Atan(z) + Btan^3(z) + Ctan^5(z) )
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- Error function refraction model
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Input parameters for the spherical atmosphere models (all but the first):
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- Temperature [K]
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- Pressure [Pa]
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- Relative humidity
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- CO2 density [ppm]
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- Latitude [deg]
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- Height above sea level [m]
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- Wavelength(s) [um]
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- Zenith angle [deg]
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**Analytical error propagation**
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Full analytical error propagation is available for the Ciddor dispersion model (Observatory.dn_tph( ) ), for the Cassini refraction model (refraction.cassiniError( ) ) and for the Cassini dispersion model (dispersion.cassiniError( ) ).
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The results agree well with a Monte Carlo simulation, suggesting that if additional errors have not been considered, they are of neglible importance.
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Uncertainties that are considered:
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Ciddor dispersion model:
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| Param. | Description | Unit |
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| ------ | ------ | ------ |
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| dl | Wavelength | um |
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| dT | Temperature | K |
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| dP | Pressure | Pa |
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| dRH | Relative Humidity | |
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| dCO2 | CO2 density | ppm |
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Cassini refraction model:
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| Param. | Description | Unit |
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| ------ | ------ | ------ |
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| dn | Refractive index | |
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| dz | Zenith angle | deg |
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Cassini dispersion model:
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| Param. | Description | Unit |
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| ------ | ------ | ------ |
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| dl1, dl2 | Wavelength(s) | um |
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| dT | Temperature | K |
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| dP | Pressure | Pa |
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| dRH | Relative Humidity | |
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| dCO2 | CO2 density | ppm |
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| dz | Zenith angle | deg |
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