asap.opacity.model Class Reference

List of all members.

Public Member Functions
def	__init__
def	get_opacities
def	set_weather
def	set_observatory_elevation
Private Member Functions
def	_to_pascals
Private Attributes
	_atm

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Detailed Description

Definition at line 11 of file opacity.py.

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Constructor & Destructor Documentation

def asap.opacity.model.__init__	(		self,
			temperature = 288,
			pressure = 101325.,
			humidity = 0.5,
			elevation = 700.
	)

This class implements opacity/atmospheric brightness temperature model
equivalent to the model available in MIRIAD. The actual math is a
convertion of the Fortran code written by Bob Sault for MIRIAD.
It implements a simple model of the atmosphere and Liebe's model (1985)
of the complex refractive index of air.

The model of the atmosphere is one with an exponential fall-off in
the water vapour content (scale height of 1540 m) and a temperature
lapse rate of 6.5 mK/m. Otherwise the atmosphere obeys the ideal gas
equation and hydrostatic equilibrium.

Note, the model includes atmospheric lines up to 800 GHz, but was not
rigorously tested above 100 GHz and for instruments located at
a significant elevation. For high-elevation sites it may be necessary to
adjust scale height and lapse rate.

Parameters:
    temperature:    air temperature at the observatory (K)
    pressure:       air pressure at the sea level if the observatory
            elevation is set to non-zero value (note, by
            default is set to 700m) or at the observatory
            ground level if the elevation is set to 0. (The
            value is in Pascals or hPa, default 101325 Pa
    humidity:       air humidity at the observatory (fractional),
            default is 0.5
    elevation:     observatory elevation about sea level (in meters)

Definition at line 18 of file opacity.py.

Referenced by asap.opacity.model._to_pascals().

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Member Function Documentation

def asap.opacity.model._to_pascals	(		self,
			val
	)		[private]

Definition at line 12 of file opacity.py.

References asap.opacity.model.__init__().

Referenced by asap.opacity.model.set_weather().

def asap.opacity.model.get_opacities	(		self,
			freq,
			elevation = None
	)

Get the opacity value(s) for the given frequency(ies).
If no elevation is given the opacities for the zenith are returned.
If an elevation is specified refraction is also taken into account.
Parameters:
    freq:       a frequency value in Hz, or a list of frequency values.
        One opacity value per frequency is returned as a scalar
        or list.
    elevation:  the elevation at which to compute the opacity. If `None`
        is given (default) the zenith opacity is returned.

Definition at line 51 of file opacity.py.

def asap.opacity.model.set_observatory_elevation	(		self,
			elevation
	)

Update the model using the given the observatory elevation
Parameters:
    elevation:  the elevation at which to compute the opacity. If `None`
        is given (default) the zenith opacity is returned.

Definition at line 93 of file opacity.py.

def asap.opacity.model.set_weather	(		self,
			temperature,
			pressure,
			humidity
	)

Update the model using the given environmental parameters.
Parameters:
    temperature:    air temperature at the observatory (K)
    pressure:       air pressure at the sea level if the observatory
            elevation is set to non-zero value (note, by
            default is set to 700m) or at the observatory
            ground level if the elevation is set to 0. (The
            value is in Pascals or hPa, default 101325 Pa
    humidity:       air humidity at the observatory (fractional),
            default is 0.5

Definition at line 78 of file opacity.py.

References asap.opacity.model._to_pascals().

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Member Data Documentation

asap.opacity.model._atm [private]

Definition at line 47 of file opacity.py.

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The documentation for this class was generated from the following file:

• asap/opacity.py