DXC
72a20adc87
gas_density() 函数第 36 行： - 原代码: (local_temperature_kelvin + standard_temperature) / standard_temperature 物理错误：T_K 已在第32行完成 °C→K 转换（+273.15），这里又加了一次 273.15， 导致体积修正因子偏大约 2 倍（对 7.4°C 数据：553.7/273.15≈2.03 而非正确的 280.55/273.15≈1.03） - 修复: local_temperature_kelvin / standard_temperature 符合理想气体定律 V₂ = V₁ × (P₁/P₂) × (T₂/T₁) 影响范围：所有通过 gas_flux_column() 计算的通量值，修复后通量约为原值的 2 倍
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."""
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import molmass
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import pandas as pd
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gas_variables = {
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"standard_pressure": 1013.25, # hPa/mbar
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"standard_temperature": 273.15, # degrees K
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"standard_molar_volume": 0.022413969545014, # m3⋅mol-1
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}
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def mass(formula: str) -> float:
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"""Return the molar mass of a gas in g/mol."""
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return molmass.Formula(formula.upper()).mass # only accepts capital letters
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def gas_density(local_pressure: float, local_temperature_celsius: float, gas: str) -> float: # millibars and celsius
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"""
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Calculate the density of a gas in kg/m3 based on local pressure and temperature.
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Parameters:
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- local_pressure: The local pressure in hPa/mbar.
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- local_temperature: The local temperature in degrees Celsius.
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- gas: The chemical formula of the gas.
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Returns:
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- The density of the gas in kg/m3.
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Assumes ideal gas behavior.
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"""
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local_temperature_kelvin = local_temperature_celsius + gas_variables["standard_temperature"]
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local_volume = (
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gas_variables["standard_molar_volume"]
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* (gas_variables["standard_pressure"] / local_pressure)
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* (local_temperature_kelvin / gas_variables["standard_temperature"])
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) # m3⋅mol-1
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return mass(gas) / 1000 / local_volume
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def gas_flux_column(df: pd.DataFrame, gas: str, wind: str = "windspeed") -> pd.DataFrame:
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"""
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Add columns to the DataFrame for the gas density, mass, and flux.
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Parameters:
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- df: The DataFrame.
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- gas: The chemical formula of the gas.
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- wind: The column name for the wind speed (NB - must be perpendicular to the plane)
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Returns:
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- The DataFrame with the added columns.
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"""
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average_temp = df["temperature"].mean() # celsius
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average_pressure = df["pressure"].mean() # hPa
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gd = gas_density(local_pressure=average_pressure, local_temperature_celsius=average_temp, gas=gas) # kg/m3
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df[f"{gas}_kg_m3"] = gd * (df[f"{gas}_normalised"] * 1e-6) # kg/m3
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df[f"{gas}_kg_h_m2"] = df[f"{gas}_kg_m3"] * df[wind] * 60 * 60 # kg/h/m2
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return df
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