Autogenerated API¶
High level functions¶
- pyseaflux.flux_calculations.flux_bulk(temp_C, salt, pCO2_sea_uatm, pCO2_air_uatm, pres_hPa, kw_cmhr)[source]¶
Calculates bulk air-sea CO2 fluxes
\[FCO_2 = k_w \cdot K_0 \cdot \Delta pCO_2\]- Parameters
temp_C (array) – temperature from OISST in degCelcius with an allowable range of [-2:45]
salt (array) – salinity from EN4 in PSU. Allowable range [5 : 50]
pCO2_sea_uatm (array) – partial pressure of CO2 in the sea in micro-atmospheres. Allowable range is [50 : 1000]
pCO2_air_uatm (array) – partial pressure of CO2 in the air in micro-atmospheres. Allowable range is [50 : 1000].
press_hPa (array) – atmospheric pressure in hecto-Pascals with allowable range [500:1500]
kw_cmhr (array) – the gas transfer velocity in (cm/hr). Given the careful choices involved in estimating kw, we require the user to explicitly provide kw. kw can be calculated with pyseaflux.gas_transfer_velocity.<func>. Things to be aware of when calculating kw: wind product and scaling coeffient of gas transfer, resolution resampling, and the formulation (i.e. quadratic, cubic).
- Returns
Sea-air CO2 flux where positive is out of the ocean and negative is into the ocean. Units are gC.m-2.day-1 (grams Carbon per metre squared per day). If the input is an xarray.DataArray, then the output will be a data array with fluxes, globally integrated flux, and the area used to integrate the fluxes.
- Return type
array
Conversions of fCO2 - pCO2¶
- pyseaflux.fco2_pco2_conversion.fCO2_to_pCO2(fCO2SW_uatm, tempSW_C, pres_hPa=1013.25, tempEQ_C=None, checks=True)[source]¶
Convert fCO2 to pCO2 in sea water.
If equilibrator temperature is provided, we get a simple approximate for equilibrator \(xCO_2\) that allows for the virial expansion to be calculated more accurately. If not, then a simple approximation is good enough. See the examples for the differences.
\[pCO_2^{sw} = fCO_2^{sw} \div virial(xCO_2^{eq})\]where \(xCO_2^{eq} = fCO_2^{sw} \times \Delta T^{(sw - eq)} \div P^{eq}\)
- Parameters
fCO2SW_uatm (array) – seawater fugacity of CO2 in micro atmospheres
tempSW_C (array) – sea water temperature in degrees C
pres_hPa (array, optional) – equilibrator pressure in hecto Pascals. Defaults to 1013.25.
tempEQ_C (array, optional) – equilibrator temperature in degrees C. Defaults to None.
- Returns
partial pressure of CO2 in seawater
- Return type
array
Note
In FluxEngine, they account fully solve for the original xCO2 that is used in the calculation of the virial expansion. I use the first estimate of xCO2 (based on fCO2 rather than pCO2). The difference between the two approaches is so small that it is not significant to be concerned. Their correction is more precise, but the difference between their iterative correction and our approximation is on the order of 1e-14 atm (1e-8 uatm).
Examples
>>> fCO2_to_pCO2(380, 8) 381.50806485658234 >>> fCO2_to_pCO2(380, 8, pres_hPa=985) 381.4659553134281 >>> fCO2_to_pCO2(380, 8, pres_hPa=985, tempEQ_C=14) 381.466027968504
- pyseaflux.fco2_pco2_conversion.pCO2_to_fCO2(pCO2SW_uatm, tempSW_C, pres_hPa=None, tempEQ_C=None, checks=False)[source]¶
Convert pCO2 to fCO2 in sea water to account for non-ideal behaviour of CO2
If equilibrator temperature is provided, we get a simple approximate for equilibrator \(xCO_2\) that allows for the virial expansion to be calculated more accurately. If not, then a simple approximation is probably good enough. See the examples for the differences.
\[pCO_2^{sw} = fCO_2^{sw} \times virial(xCO_2^{eq})\]where \(xCO_2^{eq} = fCO_2^{sw} \times \Delta T^{(sw - eq)} \div P^{eq}\)
- Parameters
fCO2SW_uatm (array) – seawater fugacity of CO2 in micro atmospheres
tempSW_C (array) – sea water temperature in degrees C
pres_hPa (array, optional) – equilibrator pressure in hecto Pascals. Defaults to 1013.25.
tempEQ_C (array, optional) – equilibrator temperature in degrees C. Defaults to None.
- Returns
fugacity of CO2 in seawater
- Return type
array
Note
In FluxEngine, they account for the change in xCO2. This error is so small that it is not significant to be concerned about it. Their correction is more precise, but the difference between their iterative correction and our approximation is less than 1e-14 atm (or 1e-8 uatm).
Examples
>>> pCO2_to_fCO2(380, 8) 378.49789637942064 >>> pCO2_to_fCO2(380, 8, pres_hPa=985) 378.53967828231225 >>> pCO2_to_fCO2(380, 8, pres_hPa=985, tempEQ_C=14) 378.53960618459695
- pyseaflux.fco2_pco2_conversion.virial_coeff(temp_K, pres_atm, xCO2_mol=None, checks=False)[source]¶
Calculate the ideal gas correction factor for converting pCO2 to fCO2.
Based on the Lewis and Wallace 1998 Correction.
- Parameters
temp_K (array) – temperature in degrees Kelvin
pres_atm (array) – atmospheric pressure in atmospheres
xCO2_mol (array, optional) – mole fraction of CO2, can also be p/fCO2 if xCO2 not available. Can also be None which makes a small difference. See examples.
- Returns
the factor to multiply/divide with pCO2/fCO2. Unitless
\[ \begin{align}\begin{aligned}fCO_2 = pCO_2 \times \text{virial expansion}\\pCO_2 = fCO_2 \div \text{virial expansion}\end{aligned}\end{align} \]- Return type
array
Examples
From Dickson et al. (2007)
>>> 350 * virial_coeff(298.15, 1) # CO2 [uatm] * correction factor 348.8836492182758
References
Weiss, R. (1974). Carbon dioxide in water and seawater: the solubility of a non-ideal gas. Marine Chemistry, 2(3), 203–215. https://doi.org/10.1016/0304-4203(74)90015-2
Compared with the Seacarb package in R
Gas Transfer Velocity¶
Modulates the magnitude of the flux between the atmosphere and the ocean.
- pyseaflux.gas_transfer_velocity.k_Ho06(wind_second_moment, temp_C)[source]¶
Calculates the gas transfer coeffcient for CO2 using the formulation of Ho et al. (2006)
The gas transfer velocity is for the QuickSCAT satellite wind product. Note that using this function for any other wind product is stricktly speaking not correct.
\[k_{600} = 0.266 \cdot U^2\]The parameterization is based on the SOLAS Air-Sea Gas Exchange (SAGE) experiment.
- Parameters
wind_ms (array) – wind speed in m/s
temp_C (array) – temperature in degrees C
- Returns
gas transfer velocity (k600) in cm/hr
- Return type
kw (array)
References
Ho, D. T., Law, C. S., Smith, M. J., Schlosser, P., Harvey, M., & Hill, P. (2006). Measurements of air-sea gas exchange at high wind speeds in the Southern Ocean: Implications for global parameterizations. Geophysical Research Letters, 33(16), 1–6. https://doi.org/10.1029/2006GL026817
- pyseaflux.gas_transfer_velocity.k_Li86(wind_ms, temp_C)[source]¶
Calculates the gas transfer coeffcient for CO2 using the formulation of Liss and Merlivat (1986)
Note
This is an old parameterization and we recommend using updated parameterisations that are calculated based on the wind product you choose to use. We include this parameterisation based purely for legacy purposes.
- Parameters
wind_ms (array) – wind speed in m/s
temp_C (array) – temperature in degrees C
- Returns
gas transfer velocity (k600) in cm/hr
- Return type
kw (array)
References
Liss, P. S., & Merlivat, L. (1986). The Role of Air-Sea Exchange in Geochemical Cycling (Vol. 1983, Issue June 1983). D. Reidel Publishing Company.
- pyseaflux.gas_transfer_velocity.k_Mc01(wind_ms, temp_C)[source]¶
Calculates the gas transfer coeffcient for CO2 using the formulation of McGillis et al. (2001)
The gas transfer velocity has been scaled for in-situ short term wind products. Note that using this function for any other wind product is not correct.
\[k_{660} = 3.3 + 0.026 \cdot U^3\]- Parameters
wind_ms (array) – wind speed in m/s
temp_C (array) – temperature in degrees C
- Returns
gas transfer velocity (k660) in cm/hr
- Return type
kw (array)
References
McGillis, W. R., Edson, J. B., Ware, J. D., Dacey, J. W. H., Hare, J. E., Fairall, C. W., & Wanninkhof, R. H. (2001). Carbon dioxide flux techniques performed during GasEx-98. Marine Chemistry, 75(4), 267–280. https://doi.org/10.1016/S0304-4203(01)00042-1
- pyseaflux.gas_transfer_velocity.k_Ni00(wind_ms, temp_C)[source]¶
Calculates the gas transfer coeffcient for CO2 using the formulation of Nightingale et al (2000)
\[k_{600} = 0.333 \cdot U + 0.222 \cdot U^2\]- Parameters
wind_ms (array) – wind speed in m/s
temp_C (array) – temperature in degrees C
- Returns
gas transfer velocity (k600) in cm/hr
- Return type
kw (array)
References
Nightingale, P. D., Malin, G., Law, C. S., Watson, A. J., Liss, P. S., Liddicoat, M. I., Boutin, J., & Upstill-Goddard, R. C. (2000). In situ evaluation of air-sea gas exchange parameterizations using novel conservative and volatile tracers. In Global Biogeochemical Cycles (Vol. 14, Issue 1, p. 373). https://doi.org/10.1029/1999GB900091
- pyseaflux.gas_transfer_velocity.k_Sw07(wind_second_moment, temp_C)[source]¶
Calculates the gas transfer coeffcient for CO2 using the formulation Wanninkhof (1992) rescaled by Sweeny et al (2007)
The gas transfer velocity has been scaled for the NCEP/NCAR reanalysis 1 product. Note that using this function for any other wind product is not correct.
\[k_{660} = 0.27 \cdot U^2\]- Parameters
wind_second_moment (array) – wind speed squared in m2/s2. Note that the second moment should be calculated at the native resolution of the wind to avoid losses of variability when taking the square product.
temp_C (array) – temperature in degrees C
- Returns
gas transfer velocity (k660) in cm/hr
- Return type
kw (array)
References
Sweeney, C., Gloor, E., Jacobson, A. R., Key, R. M., McKinley, G. A., Sarmiento, J. L., & Wanninkhof, R. H. (2007). Constraining global air-sea gas exchange for CO2 with recent bomb 14C measurements. Global Biogeochemical Cycles, 21(2). https://doi.org/10.1029/2006GB002784
- pyseaflux.gas_transfer_velocity.k_Wa09(wind_ms, temp_C)[source]¶
Calculates the gas transfer coeffcient for CO2 using the formulation of Wanninkhof et al. (2009)
The gas transfer velocity has been scaled for the Cross-Calibrated Multi- Platform (CCMP) Winds product. Note that using this function for any other wind product is not correct.
\[k_{660} = 3.0 + 0.1 \cdot U + 0.064 \cdot U^2 + 0.011 \cdot U^3\]- Parameters
wind_ms (array) – wind speed in m/s
temp_C (array) – temperature in degrees C
- Returns
gas transfer velocity (k660) in cm/hr
- Return type
kw (array)
References
Wanninkhof, R. H., Asher, W. E., Ho, D. T., Sweeney, C., & McGillis, W. R. (2009). Advances in Quantifying Air-Sea Gas Exchange and Environmental Forcing*. Annual Review of Marine Science, 1(1), 213–244. https://doi.org/10.1146/annurev.marine.010908.163742
- pyseaflux.gas_transfer_velocity.k_Wa14(wind_second_moment, temp_C)[source]¶
Calculates the gas transfer coeffcient for CO2 using the formulation of Wanninkhof et al. (2014)
The gas transfer velocity has been scaled for the Cross-Calibrated Multi- Platform (CCMP) Winds product. Note that using this function for any other wind product is not correct.
\[k_{660} = 0.251 \cdot U^2\]- Parameters
wind_second_moment (array) – wind speed squared in m2/s2. Note that the second moment should be calculated at the native resolution of the wind to avoid losses of variability when taking the square product.
temp_C (array) – temperature in degrees C
- Returns
gas transfer velocity (k660) in cm/hr
- Return type
kw (array)
References
Wanninkhof, R. H. (2014). Relationship between wind speed and gas exchange over the ocean revisited. Limnology and Oceanography: Methods, 12(JUN), 351–362. https://doi.org/10.4319/lom.2014.12.351
- pyseaflux.gas_transfer_velocity.k_Wa92(wind_second_moment, temp_C)[source]¶
Calculates the gas transfer coeffcient for CO2 using the formulation of Wanninkhof (1992)
Note
This is an old parameterization and we recommend using updated parameterisations that are calculated based on the wind product you choose to use. We include this parameterisation based purely for legacy purposes.
The gas transfer velocity is scaled from instantaneous wind speeds. The study applies a correction to the scaling (0.39) based on instantaneous wind speeds to lower it to 0.31. This correction is based on the variability of wind.
\[k_{660} = 0.31 \cdot U^2\]- Parameters
wind_second_moment (array) – wind speed squared in m2/s2. Note that the
the (second moment should be calculated at the native resolution of) –
product. (wind to avoid losses of variability when taking the square) –
temp_C (array) – temperature in degrees C
- Returns
gas transfer velocity (k660) in cm/hr
- Return type
kw (array)
References
Wanninkhof, R. H. (1992). Relationship between wind speed and gas exchange over the ocean. Journal of Geophysical Research, 97(C5), 7373. https://doi.org/10.1029/92JC00188
- pyseaflux.gas_transfer_velocity.k_Wa99(wind_ms, temp_C)[source]¶
Calculates the gas transfer coeffcient for CO2 using the formulation of Wanninkhof and McGillis (1999)
The gas transfer velocity has been scaled for in-situ short term wind products. Note that using this function for any other wind product is not correct.
\[k_{600} = 0.0283 \cdot U^3\]- Parameters
wind_ms (array) – wind speed in m/s
temp_C (array) – temperature in degrees C
- Returns
gas transfer velocity (k600) in cm/hr
- Return type
kw (array)
References
Wanninkhof, R. H., & McGillis, W. R. (1999). A cubic relationship between air-sea CO2 exchange and wind speed. Geophysical Research Letters, 26(13), 1889–1892. https://doi.org/10.1029/1999GL900363
- pyseaflux.gas_transfer_velocity.schmidt_number(temp_C)[source]¶
Calculates the Schmidt number as defined by Jahne et al. (1987) and listed in Wanninkhof (2014) Table 1.
- Parameters
temp_C (array) – temperature in degrees C
- Returns
Schmidt number (dimensionless)
- Return type
array
Examples
>>> schmidt_number(20) # from Wanninkhof (2014) 668.344
References
Jähne, B., Heinz, G., & Dietrich, W. (1987). Measurement of the diffusion coefficients of sparingly soluble gases in water. Journal of Geophysical Research: Oceans, 92(C10), 10767–10776. https://doi.org/10.1029/JC092iC10p10767
CO2 solubility in seawater¶
- pyseaflux.solubility.solubility_weiss1974(salt, temp_K, press_atm=1, checks=True)[source]¶
Calculates the solubility of CO2 in sea water
Used in the calculation of air-sea CO2 fluxes. We use the formulation by Weiss (1974) summarised in Wanninkhof (2014).
- Parameters
salt (array) – salinity in PSU
temp_K (array) – temperature in deg Kelvin
press_atm (array) – pressure in atmospheres. Used in the solubility correction for water vapour pressure. If not given, assumed that press_atm is 1atm
- Returns
solubility of CO2 in seawater (\(K_0\)) in mol/L/atm
- Return type
array
Examples
from Weiss (1974) Table 2 but with pH2O correction
>>> solubility_weiss1974(35, 299.15) 0.029285284543519093
Water vapour pressure¶
- pyseaflux.vapour_pressure.dickson2007(salt, temp_K, checks=False)[source]¶
Water vapour pressure of seawater after Dickson et al. (2007)
Calculates \(pH_2O\) at a given salinity and temperature using the methods defined in Dickson et al. (2007; CO2 manual)
- Parameters
salt (np.array) – salinity
temp_K (np.array) – temperature in deg Kelvin
- Returns
sea_vapress – sea water vapour pressure in atm
- Return type
np.array
Examples
>>> vapress_dickson2007(35, 298.15) # from Dickson et al. (2007) Ch 5.3.2 0.030698866245809465
- pyseaflux.vapour_pressure.weiss1980(salt, temp_K, checks=False)[source]¶
Water vapour pressure of seawater after Weiss and Price (1980)
For a given salinity and temperature using the methods defined in Weiss (1974)
- Parameters
salt (array) – salinity in PSU
temp_K (array) – temperature in deg Kelvin
- Returns
sea water vapour pressure in atm (\(pH_2O\))
- Return type
array
Examples
>>> vapress_weiss1980(35, 25+273.15) # tempC + 273.15 0.03065529996317971
References
Weiss, R. (1974). Carbon dioxide in water and seawater: the solubility of a non-ideal gas. Marine Chemistry, 2(3), 203–215. https://doi.org/10.1016/0304-4203(74)90015-2
Weiss, R., & Price, B. a. (1980). Nitrous oxide solubility in water and seawater. Marine Chemistry, 8(4), 347–359. https://doi.org/10.1016/0304-4203(80)90024-9
Additional equations¶
Not necessarily linked to the marine carbonate system, but are useful.
- pyseaflux.auxiliary_equations.pressure_height_correction(pres_hPa, tempSW_C, sensor_height=10.0, checks=True)[source]¶
Returns exact sea level pressure if the sensor is measuring at height
- Parameters
pres_hPa (array) – Pressure in kiloPascal measured at height
tempSW_C (array) – Temperature of the seawater in deg C
sensor_height (float, optional) – the height of the sensor above sea level. Can be negative if you want to convert SLP to sensor height pressure. Defaults to 10.0.
- Returns
height corrected pressure
- Return type
array
- pyseaflux.auxiliary_equations.temperature_correction(temp_in, temp_out)[source]¶
pCO2 correction factor for temperature changes
Calculate a correction factor for the temperature difference between the intake and equilibrator. This is based on the empirical relationship used in Takahashi et al. 1993.
\[pCO_2^{Tout} = pCO_2^{Tin} * T^{factor}\]- Parameters
temp_in (array) – temperature at which original pCO2 is measured (degK or degC)
temp_out (array) – temperature for which pCO2 should be represented
- Returns
a correction factor to be multiplied to pCO2 (unitless)
- Return type
array
References
Takahashi, Taro et al. (1993). Seasonal variation of CO2 and nutrients in the high-latitude surface oceans: A comparative study. Global Biogeochemical Cycles, 7(4), 843–878. https://doi.org/10.1029/93GB02263
Area calculations¶
Calculates the area of pixels for a give grid input.
- pyseaflux.area.area_grid(lat, lon, return_dataarray=False)[source]¶
Calculate the area of each grid cell for given lats and lons
- Parameters
lat (array) – latitudes in decimal degrees of length N
lon (array) – longitudes in decimal degrees of length M
return_dataarray (bool, optional) – if True returns xr.DataArray, else array
- Returns
area of each grid cell in meters
- Return type
array, xr.DataArray
References
https://github.com/chadagreene/CDT/blob/master/cdt/cdtarea.m
This module is only intended to be by the SeaFlux authors to download the data required to create the SeaFlux ensemble. Has links to most data sources (ERA5 might not be included)
Hence, this module is not imported by default and submodules should be imported on demand.