def test_rh_spec_humidity(self):
"""Tests specific humidity -> RH calculation
Starting from an RH, an atmospheric pressure and temperature,
calculate specific humidity. Then check to see if the tested code
can reproduce the RH we started with.
"""
rh = 25 * u.pct
p = 1 * u.bar
t = 25 * u.deg_C
e_sat = vp.calc_vp(t)
w_sat = m.mixing_ratio(e_sat, p)
w = rh * w_sat # get vapor pressure from definition of RH
e = p * w / (m.EPSILON + w) # mixing ratio solved for e
# calculate specific humidity using eq 2.19
q = m.EPSILON * (e / (p - (1 - m.EPSILON) * e))
rh_test = m.calc_rh_spec_humidity(q, p, t)
self.assertTrue(np.abs(rh - rh_test) < 0.1 * u.pct,
msg="test RH: {:3.1} ; calculated RH: {:3.1}".format(
rh, rh_test))
def calc_vpd(Tday, vp_act):
"""Calculate vapor pressure deficit given the measured temperature and
actual (modeled) vapor pressure. Returns the VPD in Pa, limited to the
range [0-9000Pa]."""
vp_sat = vp.calc_vp(Tday)
vpd = vp_sat - vp_act
np.clip(vpd, 0 * u.Pa, 9000 * u.Pa)
return vpd
def calc_vpd(Tday, vp_act):
"""Calculate vapor pressure deficit given the measured temperature and
actual (modeled) vapor pressure. Returns the VPD in Pa, limited to the
range [0-9000Pa]."""
vp_sat = vp.calc_vp(Tday)
vpd = vp_sat - vp_act
np.clip(vpd, 0 * u.Pa, 9000 * u.Pa)
return vpd
def calc_rh_spec_humidity(q, p, t):
"""RH is needed for the various NFDRS fuel moistures.
Implements equation 2.20 (p. 17) of [1].
Returns a relative humidity as a fraction 0..1, not as a percent 0..100.
[1] Rogers, R. R. A Short Course in Cloud Physics, Third Edition.
3 edition. Oxford ; New York: Pergamon, 1989.
"""
e = calc_vp_spec_humidity(q, p)
w = mixing_ratio(e, p)
e_sat = vp.calc_vp(t)
w_sat = mixing_ratio(e_sat, p)
return (w / w_sat).to(u.pct)
def calc_rh_spec_humidity(q, p, t):
"""RH is needed for the various NFDRS fuel moistures.
Implements equation 2.20 (p. 17) of [1].
Returns a relative humidity as a fraction 0..1, not as a percent 0..100.
[1] Rogers, R. R. A Short Course in Cloud Physics, Third Edition.
3 edition. Oxford ; New York: Pergamon, 1989.
"""
e = calc_vp_spec_humidity(q, p)
w = mixing_ratio(e, p)
e_sat = vp.calc_vp(t)
w_sat = mixing_ratio(e_sat, p)
return (w / w_sat).to(u.pct)
def test_rh_spec_humidity(self) :
"""Tests specific humidity -> RH calculation
Starting from an RH, an atmospheric pressure and temperature,
calculate specific humidity. Then check to see if the tested code
can reproduce the RH we started with.
"""
rh = 25 * u.pct
p = 1 * u.bar
t = 25 * u.deg_C
e_sat = vp.calc_vp(t)
w_sat = m.mixing_ratio(e_sat, p)
w = rh * w_sat # get vapor pressure from definition of RH
e = p*w/(m.EPSILON + w) # mixing ratio solved for e
# calculate specific humidity using eq 2.19
q = m.EPSILON * (e/(p-(1-m.EPSILON)*e))
rh_test = m.calc_rh_spec_humidity(q, p, t)
self.assertTrue(np.abs(rh-rh_test) < 0.1 * u.pct,
msg="test RH: {:3.1} ; calculated RH: {:3.1}".format(rh, rh_test))