brightwind.analyse.analyse.calc_air_density

brightwind.analyse.analyse.calc_air_density(temperature, pressure, elevation_ref=None, elevation_site=None, lapse_rate=-0.113, specific_gas_constant=286.9)

Calculates air density for a given temperature and pressure and extrapolates that to the site if both reference and site elevations are given.

Parameters

• temperature (float or pandas.Series or pandas.DataFrame) – Temperature values in degree Celsius

• pressure (float or pandas.Series or pandas.DataFrame) – Pressure values in hectopascal, hPa, (1,013.25 hPa = 101,325 Pa = 101.325 kPa = 1 atm = 1013.25 mbar)

• elevation_ref (Floating point value (decimal number)) – Elevation, in meters, of the reference temperature and pressure location.

• elevation_site (Floating point values (decimal number)) – Elevation, in meters, of the site location to calculate air density for.

• lapse_rate (Floating point value (decimal number)) – Air density lapse rate kg/m^3/km, default is -0.113

• specific_gas_constant (Floating point value (decimal number)) – Specific gas constant, R, for humid air J/(kg.K), default is 286.9

Returns

Air density in kg/m^3

Return type

float or pandas.Series depending on the input

Example usage

::

import brightwind as bw

#For a series of air densities data = bw.load_campbell_scientific(bw.datasets.demo_campbell_scientific_site_data) air_density = bw.calc_air_density(data.T2m, data.P2m)

#For a single value bw.calc_air_density(15, 1013)

#For a single value with ref and site elevation bw.calc_air_density(15, 1013, elevation_ref=0, elevation_site=200)