adding new isotope equil. fractionation factor formulae for ice-vap 2H (LambEtAl2017, EllehojEtAl2013) + new example notebook (Fig. 4 from Lamb et al. 2017, PNAS)

PySDM/physics/constants_defaults.py

@@ -212,6 +212,16 @@
 MERLIVAT_NIEF_1967_ALPHA_I_2H_T1 = 0 * si.K
 MERLIVAT_NIEF_1967_ALPHA_I_2H_T0 = -0.0945
 
+""" [Lamb et al. (2017)](https://doi.org/10.1073/pnas.1618374114) """
+LAMB_ET_AL_2017_ALPHA_I_2H_T2 = 13525 * si.K**2
+LAMB_ET_AL_2017_ALPHA_I_2H_T1 = 0 * si.K
+LAMB_ET_AL_2017_ALPHA_I_2H_T0 = -0.0559
+
+""" [Ellehoj et al. (2013)](https://doi.org/10.1002/rcm.6668) """
+ELLEHOJ_ET_AL_2013_ALPHA_I_2H_T2 = 48888 * si.K**2
+ELLEHOJ_ET_AL_2013_ALPHA_I_2H_T1 = -203.1 * si.K
+ELLEHOJ_ET_AL_2013_ALPHA_I_2H_T0 = 0.2133
+
 """ [Majoube (1971)](https://doi.org/10.1051/jcp/1971681423) """
 # values taken from Jouzel 1986 (eqs. 1)
 MAJOUBE_1971_ALPHA_L_18O_T2 = 1137 * si.K**2

PySDM/physics/isotope_equilibrium_fractionation_factors/__init__.py

@@ -11,3 +11,5 @@
 from .null import Null
 from .pierchala_et_al_2022 import PierchalaEtAl2022
 from .van_hook_1968 import VanHook1968
+from .lamb_et_al_2017 import LambEtAl2017
+from .ellehoj_et_al_2013 import EllehojEtAl2013

PySDM/physics/isotope_equilibrium_fractionation_factors/ellehoj_et_al_2013.py

@@ -0,0 +1,19 @@
+"""
+Equilibrium fractionation factors from
+[Ellehoj et al. 2013](https://doi.org/10.1002/rcm.6668)
+"""
+
+import numpy as np
+
+
+class EllehojEtAl2013:  # pylint: disable=too-few-public-methods
+    def __init__(self, _):
+        pass
+
+    @staticmethod
+    def alpha_i_2H(const, T):
+        return np.exp(
+            const.ELLEHOJ_ET_AL_2013_ALPHA_I_2H_T2 / T**2
+            + const.ELLEHOJ_ET_AL_2013_ALPHA_I_2H_T1 / T
+            + const.ELLEHOJ_ET_AL_2013_ALPHA_I_2H_T0
+        )

PySDM/physics/isotope_equilibrium_fractionation_factors/lamb_et_al_2017.py

@@ -0,0 +1,19 @@
+"""
+Equilibrium fractionation factors from
+[Lamb et al. 2017](https://doi.org/10.1073/pnas.1618374114)
+"""
+
+import numpy as np
+
+
+class LambEtAl2017:  # pylint: disable=too-few-public-methods
+    def __init__(self, _):
+        pass
+
+    @staticmethod
+    def alpha_i_2H(const, T):
+        return np.exp(
+            const.LAMB_ET_AL_2017_ALPHA_I_2H_T2 / T**2
+            + const.LAMB_ET_AL_2017_ALPHA_I_2H_T1 / T
+            + const.LAMB_ET_AL_2017_ALPHA_I_2H_T0
+        )

examples/PySDM_examples/Lamb_et_al_2017/__init__.py

@@ -0,0 +1,5 @@
+# pylint: disable=invalid-name
+"""
+Formulae-only example depicting equilibrium isotopic fractionation over ice based on
+[Lamb et al. 2017](https://doi.org/10.1073/pnas.1618374114)
+"""