def process(self):
"""
Create a saturated vapour pressure lookup table by calling the
Utilities.saturation_vapour_pressure_goff_gratch function in
psychrometric_calculations.Utilities.
Returns:
svp : iris.cube.Cube
A cube of saturated vapour pressure values at temperature
points defined by t_min, t_max, and t_increment (defined above).
"""
temperatures = np.arange(self.t_min, self.t_max + 0.5*self.t_increment,
self.t_increment)
temperature = iris.cube.Cube(temperatures, 'air_temperature',
units='K')
svp = Utilities.saturation_vapour_pressure_goff_gratch(temperature)
temperature_coord = iris.coords.DimCoord(
temperature.data, 'air_temperature', units='K')
svp.add_dim_coord(temperature_coord, 0)
svp.attributes['minimum_temperature'] = self.t_min
svp.attributes['maximum_temperature'] = self.t_max
svp.attributes['temperature_increment'] = self.t_increment
return svp
def test_basic(self):
"""Basic calculation of some saturated vapour pressures."""
result = Utilities.saturation_vapour_pressure_goff_gratch(
self.temperature)
expected = [195.64190713, 469.67078994, 990.94206073]
np.testing.assert_allclose(result.data, expected, rtol=1.e-5)
self.assertEqual(result.units, Unit('Pa'))