def do_thermodynamics(self):
assert 'temp' in self.soundingdata, \
"Temperature needed for thermodynamics! Add TEMP"
assert 'pres' in self.soundingdata, \
"Pressure needed for thermodynamics! Add PRES"
assert 'dwpt' in self.soundingdata, \
"Moisture needed for thermodynamics! Add DWPT"
# primary variables
prespa = self.soundingdata['pres'] * 100.
tempc = self.soundingdata['temp']
tempk = tempc + degCtoK
dwptc = self.soundingdata['dwpt']
# secondary variables
e = VaporPressure(dwptc)
esat = VaporPressure(tempc)
# assign/extract other variables
if 'thta' not in self.soundingdata:
self.soundingdata['thta'] = Theta(tempk, prespa)
if 'thte' not in self.soundingdata:
self.soundingdata['thte'] = ThetaE(tempk, prespa, e)
if 'thtv' not in self.soundingdata:
self.soundingdata['thtv'] = ThetaV(tempk, prespa, e)
if 'relh' not in self.soundingdata:
self.soundingdata['relh'] = 100. * e / esat
return
def precipitable_water(self):
"""Calculate Total Precipitable Water (TPW) for sounding.
TPW is defined as the total column-integrated water vapour. I
calculate it from the dew point temperature because this is the
fundamental moisture variable in this module (even though it is RH
that is usually measured directly)
"""
tempk = self.soundingdata['temp'] + degCtoK
prespa = self.soundingdata['pres'] * 100.
hghtm = self.soundingdata['hght']
# Get Water Vapour Mixing Ratio, by calculation
# from dew point temperature
try:
dwptc = self.soundingdata['dwpt']
except KeyError:
print("Warning: No MIXR or DWPT for TPW calculation")
return -999.
vprespa = VaporPressure(dwptc)
mixrkg = MixRatio(vprespa, prespa)
# Calculate density of air (accounting for moisture)
rho = DensHumid(tempk, prespa, vprespa)
# Trapezoidal rule to approximate TPW (units kg/m^2==mm)
tpw = trapz(mixrkg*rho, hghtm)
return tpw
def mixed_layer_parcel(self, depth=100):
"""Returns parameters for a parcel initialised by:
1. Surface pressure (i.e. pressure of lowest level)
2. Surface temperature determined from mean(theta) of lowest <depth> mb
3. Dew point temperature representative of lowest <depth> mbar
Inputs:
depth (mbar): depth to average mixing ratio over
"""
pres = self.soundingdata["pres"]
temp = self.soundingdata["temp"]
dwpt = self.soundingdata["dwpt"]
pres0, temp0, dwpt0, null = self.surface_parcel()
# identify the layers for averaging
layers = pres > (pres0-depth)
# average theta over mixheight to give
# parcel temperature
thta_mix = Theta(temp[layers]+degCtoK, pres[layers]*100.).mean()
temp_s = TempK(thta_mix, pres0*100) - degCtoK
# average mixing ratio over mixheight
vpres = VaporPressure(dwpt)
mixr = MixRatio(vpres, pres*100)
mixr_mix = mixr[layers].mean()
vpres_s = MixR2VaporPress(mixr_mix, pres0*100)
# surface dew point temp
dwpt_s = DewPoint(vpres_s)
# print "----- Mixed Layer Parcel Characteristics -----"
# print "Mixed layer depth : %5d mb "%depth
# print "Mean mixed layer potential temperature: %5.1f K"%thta_mix
# print "Mean mixed layer mixing ratio : %5.2f g/kg"%
# (mixr_mix*1e3)
return pres0, temp_s, dwpt_s, 'ml'
raise NotImplementedError
def dry_ascent(startp, startt, startdp, nsteps=101):
from numpy import interp
# -------------------------------------------------------------------
# Lift a parcel dry adiabatically from startp to LCL.
# Init temp is startt in C, Init dew point is stwrtdp,
# pressure levels are in hPa
# -------------------------------------------------------------------
assert startdp <= startt
if startdp == startt:
return array([startp]), array([startt]), array([startdp]),
# Pres=linspace(startp,600,nsteps)
Pres = logspace(log10(startp), log10(600), nsteps)
# Lift the dry parcel
T_dry = (startt+degCtoK) * (Pres/startp)**(Rs_da/Cp_da) - degCtoK
# Mixing ratio isopleth
starte = VaporPressure(startdp)
startw = MixRatio(starte, startp*100)
e = Pres * startw / (.622+startw)
T_iso = 243.5 / (17.67/log(e/6.112)-1)
# Solve for the intersection of these lines (LCL).
# interp requires the x argument (argument 2)
# to be ascending in order!
P_lcl = interp(0, T_iso-T_dry, Pres)
T_lcl = interp(P_lcl, Pres[::-1], T_dry[::-1])
# presdry=linspace(startp,P_lcl)
presdry = logspace(log10(startp), log10(P_lcl), nsteps)
tempdry = interp(presdry, Pres[::-1], T_dry[::-1])
tempiso = interp(presdry, Pres[::-1], T_iso[::-1])
return presdry, tempdry, tempiso
rgrFreezingLevel[st, iTT] = 0
else:
f = interp1d(rgrData_act[rgsSondVars.index('T'), :],
rgrData_act[rgsSondVars.index('Z'), :])
rgrFreezingLevel[st, iTT] = f(0)
if rgrData_act[rgsSondVars.index('T'), 0] <= 3:
rgr3CLevel[st, iTT] = 0
else:
f = interp1d(rgrData_act[rgsSondVars.index('T'), :],
rgrData_act[rgsSondVars.index('Z'), :])
rgr3CLevel[st, iTT] = f(3)
# calculate melting level height
ESAT = esat(rgrData_act[rgsSondVars.index('T'), :] +
273.15)
ee = VaporPressure(
rgrData_act[rgsSondVars.index('T'), :] -
rgrData_act[rgsSondVars.index('DPD'), :],
phase="liquid")
rgrMixRatio = MixRatio(
ee, rgrData_act[rgsSondVars.index('P'), :])
VapPres = MixR2VaporPress(
rgrMixRatio, rgrData_act[rgsSondVars.index('P'), :])
rgrRH = (VapPres / ESAT) * 100.
rgrWBT = WetBulb(rgrData_act[rgsSondVars.index('T'), :],
rgrRH)
if rgrWBT[0] <= 0:
rgrWBZ[st, iTT] = 0
else:
f = interp1d(rgrWBT,
rgrData_act[rgsSondVars.index('Z'), :])
rgrWBZ[st, iTT] = f(0)
# rSolPrecProb=fnSolidPrecip(1,-5,0)