refactor saturation vapour pressure formulae to avoid using temperatures in Celsius (#1388)

Co-authored-by: Sylwester Arabas <[email protected]>

Author: BorisKonstantinov

.pre-commit-config.yaml

@@ -18,4 +18,4 @@ repos:
     hooks:
       - id: trailing-whitespace
       - id: end-of-file-fixer
-      - id: debug-statements
+      - id: debug-statements

PySDM/backends/impl_numba/methods/condensation_methods.py

@@ -291,9 +291,7 @@ def step_impl(  # pylint: disable=too-many-arguments,too-many-locals
                 )
                 pv = formulae.state_variable_triplet__pv(p, water_vapour_mixing_ratio)
                 lv = formulae.latent_heat__lv(T)
-                pvs = formulae.saturation_vapour_pressure__pvs_Celsius(
-                    T - formulae.constants.T0
-                )
+                pvs = formulae.saturation_vapour_pressure__pvs_water(T)
                 DTp = formulae.diffusion_thermics__D(T, p)
                 RH = pv / pvs
                 Sc = formulae.trivia__air_schmidt_number(

PySDM/backends/impl_numba/methods/physics_methods.py

@@ -59,7 +59,7 @@ def body(*, rhod, thd, water_vapour_mixing_ratio, T, p, RH):
                 )
                 RH[i] = ff.state_variable_triplet__pv(
                     p[i], water_vapour_mixing_ratio[i]
-                ) / ff.saturation_vapour_pressure__pvs_Celsius(T[i] - ff.constants.T0)
+                ) / ff.saturation_vapour_pressure__pvs_water(T[i])
 
         return body
 
@@ -82,9 +82,7 @@ def _a_w_ice_body(self):
         @numba.njit(**self.default_jit_flags)
         def body(*, T_in, p_in, RH_in, water_vapour_mixing_ratio_in, a_w_ice_out):
             for i in prange(T_in.shape[0]):  # pylint: disable=not-an-iterable
-                pvi = ff.saturation_vapour_pressure__ice_Celsius(
-                    T_in[i] - ff.constants.T0
-                )
+                pvi = ff.saturation_vapour_pressure__pvs_ice(T_in[i])
                 pv = ff.state_variable_triplet__pv(
                     p_in[i], water_vapour_mixing_ratio_in[i]
                 )

PySDM/backends/impl_numba/test_helpers/scipy_ode_condensation_solver.py

@@ -18,7 +18,7 @@
     _CellData,
     _Counters,
 )
-from PySDM.physics.constants_defaults import PI_4_3, T0
+from PySDM.physics.constants_defaults import PI_4_3
 
 idx_thd = 0
 idx_x = 1
@@ -205,7 +205,7 @@ def _odesys(  # pylint: disable=too-many-arguments,too-many-locals
         T = jit_formulae.state_variable_triplet__T(rhod, thd)
         p = jit_formulae.state_variable_triplet__p(rhod, T, water_vapour_mixing_ratio)
         pv = jit_formulae.state_variable_triplet__pv(p, water_vapour_mixing_ratio)
-        pvs = jit_formulae.saturation_vapour_pressure__pvs_Celsius(T - T0)
+        pvs = jit_formulae.saturation_vapour_pressure__pvs_water(T)
         RH = pv / pvs
 
         dy_dt = np.empty_like(y)

PySDM/backends/impl_thrust_rtc/methods/condensation_methods.py

@@ -318,8 +318,8 @@ def __pre(self):
                 p='p[i]', water_vapour_mixing_ratio='predicted_water_vapour_mixing_ratio[i]')};
             lv[i] = {phys.latent_heat.lv.c_inline(
                 T='T[i]')};
-            pvs[i] = {phys.saturation_vapour_pressure.pvs_Celsius.c_inline(
-                T='T[i] - const.T0')};
+            pvs[i] = {phys.saturation_vapour_pressure.pvs_water.c_inline(
+                T='T[i]')};
             RH[i] = pv[i] / pvs[i];
             RH_max[i] = max(RH_max[i], RH[i]);
             DTp[i] = {phys.diffusion_thermics.D.c_inline(

PySDM/backends/impl_thrust_rtc/methods/physics_methods.py

@@ -27,9 +27,7 @@ def _temperature_pressure_rh_body(self):
             )};
             RH[i] = {self.formulae.state_variable_triplet.pv.c_inline(
                 p="p[i]", water_vapour_mixing_ratio="water_vapour_mixing_ratio[i]"
-            )} / {self.formulae.saturation_vapour_pressure.pvs_Celsius.c_inline(
-                T="T[i] - const.T0"
-            )};
+            )} / {self.formulae.saturation_vapour_pressure.pvs_water.c_inline(T="T[i]")};
             """.replace(
                 "real_type", self._get_c_type()
             ),

PySDM/physics/saturation_vapour_pressure/august_roche_magnus.py

@@ -12,10 +12,12 @@ def __init__(self, _):
         pass
 
     @staticmethod
-    def pvs_Celsius(const, T):
-        return const.ARM_C1 * np.exp((const.ARM_C2 * T) / (T + const.ARM_C3))
+    def pvs_water(const, T):
+        return const.ARM_C1 * np.exp(
+            (const.ARM_C2 * (T - const.T0)) / ((T - const.T0) + const.ARM_C3)
+        )
 
     @staticmethod
-    def ice_Celsius(const, T):
+    def pvs_ice(const, T):
         """NaN with unit of pressure and correct dimension"""
-        return np.nan * T / const.ARM_C3 * const.ARM_C1
+        return np.nan * (T - const.T0) / const.ARM_C3 * const.ARM_C1

PySDM/physics/saturation_vapour_pressure/bolton_1980.py

@@ -10,11 +10,13 @@ def __init__(self, _):
         pass
 
     @staticmethod
-    def pvs_Celsius(const, T):
-        """valid for -30 <= T <= 35 C, eq (10)"""
-        return const.B80W_G0 * np.exp((const.B80W_G1 * T) / (T + const.B80W_G2))
+    def pvs_water(const, T):
+        """valid for 243.15(-30) <= T <= 308.15(35) K(C), eq. (10)"""
+        return const.B80W_G0 * np.exp(
+            (const.B80W_G1 * (T - const.T0)) / ((T - const.T0) + const.B80W_G2)
+        )
 
     @staticmethod
-    def ice_Celsius(const, T):
+    def pvs_ice(const, T):
         """NaN with unit of pressure and correct dimension"""
-        return np.nan * T / const.B80W_G2 * const.B80W_G0
+        return np.nan * (T - const.T0) / const.B80W_G2 * const.B80W_G0

PySDM/physics/saturation_vapour_pressure/flatau_walko_cotton.py

@@ -9,45 +9,55 @@ def __init__(self, _):
         pass
 
     @staticmethod
-    def pvs_Celsius(const, T):
-        return const.FWC_C0 + T * (
+    def pvs_water(const, T):
+        return const.FWC_C0 + (T - const.T0) * (
             const.FWC_C1
-            + T
+            + (T - const.T0)
             * (
                 const.FWC_C2
-                + T
+                + (T - const.T0)
                 * (
                     const.FWC_C3
-                    + T
+                    + (T - const.T0)
                     * (
                         const.FWC_C4
-                        + T
+                        + (T - const.T0)
                         * (
                             const.FWC_C5
-                            + T * (const.FWC_C6 + T * (const.FWC_C7 + T * const.FWC_C8))
+                            + (T - const.T0)
+                            * (
+                                const.FWC_C6
+                                + (T - const.T0)
+                                * (const.FWC_C7 + (T - const.T0) * const.FWC_C8)
+                            )
                         )
                     )
                 )
             )
         )
 
     @staticmethod
-    def ice_Celsius(const, T):
-        return const.FWC_I0 + T * (
+    def pvs_ice(const, T):
+        return const.FWC_I0 + (T - const.T0) * (
             const.FWC_I1
-            + T
+            + (T - const.T0)
             * (
                 const.FWC_I2
-                + T
+                + (T - const.T0)
                 * (
                     const.FWC_I3
-                    + T
+                    + (T - const.T0)
                     * (
                         const.FWC_I4
-                        + T
+                        + (T - const.T0)
                         * (
                             const.FWC_I5
-                            + T * (const.FWC_I6 + T * (const.FWC_I7 + T * const.FWC_I8))
+                            + (T - const.T0)
+                            * (
+                                const.FWC_I6
+                                + (T - const.T0)
+                                * (const.FWC_I7 + (T - const.T0) * const.FWC_I8)
+                            )
                         )
                     )
                 )

PySDM/physics/saturation_vapour_pressure/lowe1977.py

@@ -9,31 +9,41 @@ def __init__(self, _):
         pass
 
     @staticmethod
-    def pvs_Celsius(const, T):
-        return const.L77W_A0 + T * (
+    def pvs_water(const, T):
+        return const.L77W_A0 + (T - const.T0) * (
             const.L77W_A1
-            + T
+            + (T - const.T0)
             * (
                 const.L77W_A2
-                + T
+                + (T - const.T0)
                 * (
                     const.L77W_A3
-                    + T * (const.L77W_A4 + T * (const.L77W_A5 + T * (const.L77W_A6)))
+                    + (T - const.T0)
+                    * (
+                        const.L77W_A4
+                        + (T - const.T0)
+                        * (const.L77W_A5 + (T - const.T0) * (const.L77W_A6))
+                    )
                 )
             )
         )
 
     @staticmethod
-    def ice_Celsius(const, T):
-        return const.L77I_A0 + T * (
+    def pvs_ice(const, T):
+        return const.L77I_A0 + (T - const.T0) * (
             const.L77I_A1
-            + T
+            + (T - const.T0)
             * (
                 const.L77I_A2
-                + T
+                + (T - const.T0)
                 * (
                     const.L77I_A3
-                    + T * (const.L77I_A4 + T * (const.L77I_A5 + T * (const.L77I_A6)))
+                    + (T - const.T0)
+                    * (
+                        const.L77I_A4
+                        + (T - const.T0)
+                        * (const.L77I_A5 + (T - const.T0) * (const.L77I_A6))
+                    )
                 )
             )
         )