59 lines
2.1 KiB
Python
59 lines
2.1 KiB
Python
"""functions related to gas transformations and calculations, e.g. density, point flux etc."""
|
|
|
|
import molmass
|
|
import pandas as pd
|
|
|
|
gas_variables = {
|
|
"standard_pressure": 1013.25, # hPa/mbar
|
|
"standard_temperature": 273.15, # degrees K
|
|
"standard_molar_volume": 0.022413969545014, # m3⋅mol-1
|
|
}
|
|
|
|
|
|
def mass(formula: str) -> float:
|
|
"""Return the molar mass of a gas in g/mol."""
|
|
return molmass.Formula(formula.upper()).mass # only accepts capital letters
|
|
|
|
|
|
def gas_density(local_pressure: float, local_temperature_celsius: float, gas: str) -> float: # millibars and celsius
|
|
"""
|
|
Calculate the density of a gas in kg/m3 based on local pressure and temperature.
|
|
|
|
Parameters:
|
|
- local_pressure: The local pressure in hPa/mbar.
|
|
- local_temperature: The local temperature in degrees Celsius.
|
|
- gas: The chemical formula of the gas.
|
|
|
|
Returns:
|
|
- The density of the gas in kg/m3.
|
|
|
|
Assumes ideal gas behavior.
|
|
"""
|
|
local_temperature_kelvin = local_temperature_celsius + gas_variables["standard_temperature"]
|
|
local_volume = (
|
|
gas_variables["standard_molar_volume"]
|
|
* (gas_variables["standard_pressure"] / local_pressure)
|
|
* ((local_temperature_kelvin + gas_variables["standard_temperature"]) / gas_variables["standard_temperature"])
|
|
) # m3⋅mol-1
|
|
return mass(gas) / 1000 / local_volume
|
|
|
|
|
|
def gas_flux_column(df: pd.DataFrame, gas: str, wind: str = "windspeed") -> pd.DataFrame:
|
|
"""
|
|
Add columns to the DataFrame for the gas density, mass, and flux.
|
|
|
|
Parameters:
|
|
- df: The DataFrame.
|
|
- gas: The chemical formula of the gas.
|
|
- wind: The column name for the wind speed (NB - must be perpendicular to the plane)
|
|
|
|
Returns:
|
|
- The DataFrame with the added columns.
|
|
"""
|
|
average_temp = df["temperature"].mean() # celsius
|
|
average_pressure = df["pressure"].mean() # hPa
|
|
gd = gas_density(local_pressure=average_pressure, local_temperature_celsius=average_temp, gas=gas) # kg/m3
|
|
df[f"{gas}_kg_m3"] = gd * (df[f"{gas}_normalised"] * 1e-6) # kg/m3
|
|
df[f"{gas}_kg_h_m2"] = df[f"{gas}_kg_m3"] * df[wind] * 60 * 60 # kg/h/m2
|
|
return df
|