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local_grb_gfs2am.py
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local_grb_gfs2am.py
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#!/usr/bin/env python
#
# gfs2am.py - For a given site latitude, longitude, and altitude, this
# script will download an appropriately-subsetted GFS forecast file in
# grib2 format from the NOAA Operational Model Archive Distribution
# System (NOMADS), then generate a corresponding set of am layers
# interpolated to the site position.
import argparse
import datetime
import dateutil.parser as dparser
import math
import pygrib
import requests
from pydap.client import open_url
import numpy as np
import os
PATH = '/Volumes/My_Book_Pro/EHT/GRIB_Files/'
# Numerical and physical constants
BADVAL = -99999. # placeholder data that is missing or not defined on level
BADVAL_TEST = -99998.
G_STD = 9.80665 # standard gravitational acceleration in m / s^2
M_AIR = 28.964 # average dry air mass [g / mole]
M_O3 = 47.997 # O3 mass [g / mole]
H2O_SUPERCOOL_LIMIT = 238. # ice assumed below this temperature [K]
PASCAL_ON_MBAR = 100. # conversion from mbar (hPa) to Pa
R_Earth = 6371* (10**3) #meters
# Ignore H2O above the pressure level defined here. This is
# needed because the vertical grid used for RH skips the 20 mbar
# level. In any case, if the small amount of water vapor in
# the stratosphere (about 2 precipitable microns) needs to be
# modeled, the best way is with a climatological profile instead
# of GFS.
H2O_TOP_PLEVEL = 29. # Ignore H2O above this pressure level.
#
# Below are constants and format strings for constructing the data
# request URL. These include the base URL for the NOMADS CGI interface,
# and various strings for formatting the arguments given to it. Note
# that some information (e.g. grid, forecast production cycle) gets
# used more than once to construct the CGI request.
#
# GFS variables to be requested, and the format string for adding them
# to the CGI request URL. The variables are
# CLWMR - Cloud liquid water mass mixing ratio [kg liquid / kg air]
# HGT - Geopotential height [m]
# O3MR - Ozone mass mixing ratio [kg O3 / kg air]
# RH - Relative Humidity [%]
# TMP - Temperature [K]
# Comment string to be printed above model layers:
LAYER_HEADER = """
#
# Layer data below were derived from NCEP GFS model data obtained
# from the NOAA Operational Model Archive Distribution System
# (NOMADS). See http://nomads.ncep.noaa.gov for more information.
#
# Production date: {0}
# Cycle: {1:02d} UT
# Product: {2}
#
# Interpolated to
#
# latitude: {3} deg. N
# longitude: {4} deg. E
# Geopotential altitude: {5} m
#
"""
#
# Function for bilinear grid interpolation. a[i_lat][i_lon] is a
# 2x2 array of adjacent points on the lon,lat grid. u,v are the
# fractional distances in grid spacing in grid spacing units from
# the "bottom left" grid point to the interpolation point.
#
def grid_interp(a, u, v):
return ( a[0][0] * (1.0 - u) * (1.0 - v) + a[1][0] * u * (1.0 - v)
+ a[0][1] * (1.0 - u) * v + a[1][1] * u * v )
#
# Parse the command line and validate arguments.
#
parser = argparse.ArgumentParser()
parser.add_argument("lat", help="site latitude [deg], (-90 to 90)",
type=float)
parser.add_argument("lon", help="site longitude [deg], (-180 to 180)",
type=float)
parser.add_argument("altitude", help="site altitude [m]",
type=float)
parser.add_argument("gfsdate", help="GFS production date (YYYYMMDD)",
type=str)
parser.add_argument("gfscycle", help="GFS production cycle (0, 6, 12, 18)",
type=int)
parser.add_argument("gfsprod", help="GFS product: anl or f000 - f384 in multiples of 3",
type=str)
args = parser.parse_args()
if (args.lat < -90. or args.lat > 90.):
parser.error("invalid latitude")
if (args.lon < -360. or args.lon > 360.):
parser.error("invalid longitude")
if (args.lon < 0.):
args.lon = args.lon + 360.0
if (args.altitude < -500.):
parser.error("invalid altitude")
try:
gfsdatetime = dparser.parse(args.gfsdate)
except:
parser.error("bad GFS production date")
if (gfsdatetime < datetime.datetime(2004, 3, 2)):
parser.error("GFS production date too early")
if (args.gfscycle not in (0, 6, 12, 18)):
parser.error("invalid GFS production cycle")
if (args.gfsprod != "anl"):
if (args.gfsprod[0:1] == "f"):
forecast_hour = int(args.gfsprod[1:])
if (forecast_hour < 0 or forecast_hour > 384):
parser.error("invalid GFS product (hour out of range)")
else:
parser.error("invalid GFS product name")
if (args.gfsprod == "anl"):
URL = 'https://nomads.ncdc.noaa.gov/thredds/fileServer/gfs-004-anl'
URL += '/' + str(args.gfsdate[0:-2]) +'/' + str(args.gfsdate) + '/' + 'gfsanl_4_' + str(args.gfsdate) +'_'
if (args.gfscycle in (0,6)):
URL += '0' + str(args.gfscycle)+ '00_000.grb2'
if (args.gfscycle in (12, 18)):
URL += str(args.gfscycle)+ '00_000.grb2'
fname = URL[-31:]
if (args.gfsprod != "anl"):
if (gfsdatetime < datetime.datetime(2015, 8, 18)):
parser.error("GFS production date too early")
URL = 'https://nomads.ncdc.noaa.gov/thredds/fileServer/gfs-004'
URL += '/' + str(args.gfsdate[0:-2]) +'/' + str(args.gfsdate) + '/' + 'gfs_4_' + str(args.gfsdate) +'_'
if (args.gfscycle in (0,6)):
URL += '0' + str(args.gfscycle)+ '00_' + str(args.gfsprod[1:]) +'.grb2'
if (args.gfscycle in (12, 18)):
URL += str(args.gfscycle)+ '00_' + str(args.gfsprod[1:]) +'.grb2'
fname = URL[-28:]
if (os.path.isdir(str(PATH)+ '/' + str(args.gfsdate[0:-2])) == False):
os.system('mkdir ' + str(PATH) +'/'+ str(args.gfsdate[0:-2]))
if (os.path.isdir(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate)) == False):
os.system('mkdir ' + str(PATH) +'/' + str(args.gfsdate[0:-2]) + '/' + str(args.gfsdate))
if (os.path.isdir(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)) == False):
os.system('mkdir ' + str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle))
if (os.path.isdir(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle) + '/' + str(args.lat) + 'N' + str(args.lon) + 'E') == False):
os.system('mkdir ' + str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle) + '/' + str(args.lat) + '_N_' + str(args.lon) + '_E')
'''
if os.path.isfile(str(PATH) + '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsprod) + '/'+ str(fname)) == False:
os.system('sudo wget ' + str(URL) + ' -P ' + str(PATH) + '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsprod) )
'''
################################################################################################################################################################
if os.path.isfile(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_levels'+'.npy') == False:
grbs = pygrib.open(str(PATH) + '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsprod) + '/'+ str(fname))
LEVELS = []
geoh_data = []
tmp_data = []
o3m_data = []
relh_data = []
clm_data = []
for grb in grbs:
if grb.parameterName == 'Temperature' and (grb.level == 10 or grb.level == 20 or grb.level == 30 or grb.level == 50 or grb.level == 70 or grb.level == 100 or grb.level == 150 or grb.level == 200 or grb.level == 250 or grb.level == 300 or grb.level == 350 or grb.level == 400 or grb.level == 450 or grb.level == 500 or grb.level == 550 or grb.level == 600 or grb.level == 650 or grb.level == 700 or grb.level == 750 or grb.level == 800 or grb.level == 850 or grb.level == 900 or grb.level == 925 or grb.level == 950 or grb.level == 975 or grb.level == 1000):
if grb.level > 1000:
continue
if grb.level < 10:
continue
d = (grb.data(lat1 = (args.lat-0.5), lat2 = (args.lat+0.5), lon1 = (args.lon-0.5), lon2 = (args.lon+0.5)))
tmp_data.append(d[0])
LEVELS.append(grb.level)
if LEVELS[0] != 1000:
if grb.level == 1000:
break
elif grb.parameterName == 'Relative humidity'and (grb.level == 10 or grb.level == 20 or grb.level == 30 or grb.level == 50 or grb.level == 70 or grb.level == 100 or grb.level == 150 or grb.level == 200 or grb.level == 250 or grb.level == 300 or grb.level == 350 or grb.level == 400 or grb.level == 450 or grb.level == 500 or grb.level == 550 or grb.level == 600 or grb.level == 650 or grb.level == 700 or grb.level == 750 or grb.level == 800 or grb.level == 850 or grb.level == 900 or grb.level == 925 or grb.level == 950 or grb.level == 975 or grb.level == 1000):
if grb.level > 1000:
continue
if grb.level < 10:
continue
d = (grb.data(lat1 = (args.lat-0.5), lat2 = (args.lat+0.5), lon1 = (args.lon-0.5), lon2 = (args.lon+0.5)))
relh_data.append(d[0])
elif grb.parameterName == 'Geopotential height'and (grb.level == 10 or grb.level == 20 or grb.level == 30 or grb.level == 50 or grb.level == 70 or grb.level == 100 or grb.level == 150 or grb.level == 200 or grb.level == 250 or grb.level == 300 or grb.level == 350 or grb.level == 400 or grb.level == 450 or grb.level == 500 or grb.level == 550 or grb.level == 600 or grb.level == 650 or grb.level == 700 or grb.level == 750 or grb.level == 800 or grb.level == 850 or grb.level == 900 or grb.level == 925 or grb.level == 950 or grb.level == 975 or grb.level == 1000):
if grb.level > 1000:
continue
if grb.level < 10:
continue
d = (grb.data(lat1 = (args.lat-0.5), lat2 = (args.lat+0.5), lon1 = (args.lon-0.5), lon2 = (args.lon+0.5)))
geoh_data.append(d[0])
elif grb.name == "Ozone mixing ratio"and (grb.level == 10 or grb.level == 20 or grb.level == 30 or grb.level == 50 or grb.level == 70 or grb.level == 100 or grb.level == 150 or grb.level == 200 or grb.level == 250 or grb.level == 300 or grb.level == 350 or grb.level == 400 or grb.level == 450 or grb.level == 500 or grb.level == 550 or grb.level == 600 or grb.level == 650 or grb.level == 700 or grb.level == 750 or grb.level == 800 or grb.level == 850 or grb.level == 900 or grb.level == 925 or grb.level == 950 or grb.level == 975 or grb.level == 1000):
if grb.level > 1000:
continue
if grb.level < 10:
continue
d = (grb.data(lat1 = (args.lat-0.5), lat2 = (args.lat+0.5), lon1 = (args.lon-0.5), lon2 = (args.lon+0.5)))
o3m_data.append(d[0])
elif grb.parameterName == 'Cloud mixing ratio'and (grb.level == 10 or grb.level == 20 or grb.level == 30 or grb.level == 50 or grb.level == 70 or grb.level == 100 or grb.level == 150 or grb.level == 200 or grb.level == 250 or grb.level == 300 or grb.level == 350 or grb.level == 400 or grb.level == 450 or grb.level == 500 or grb.level == 550 or grb.level == 600 or grb.level == 650 or grb.level == 700 or grb.level == 750 or grb.level == 800 or grb.level == 850 or grb.level == 900 or grb.level == 925 or grb.level == 950 or grb.level == 975 or grb.level == 1000):
if grb.level > 1000:
continue
if grb.level < 10:
continue
d = (grb.data(lat1 = (args.lat-0.5), lat2 = (args.lat+0.5), lon1 = (args.lon-0.5), lon2 = (args.lon+0.5)))
clm_data.append(d[0])
tmp_data = np.array(tmp_data)
LEVELS = np.array(LEVELS)
geoh_data = np.array(geoh_data)
o3m_data = np.array(o3m_data)
relh_data = np.array(relh_data)
clm_data = np.array(clm_data)
np.save(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_' + str(args.gfsprod)+ '_T'+'.npy',tmp_data)
np.save(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_RH'+'.npy', relh_data)
np.save(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_z'+'.npy', geoh_data)
np.save(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_o3_vmr'+'.npy', o3m_data)
np.save(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_cloud_mr'+'.npy', clm_data)
np.save(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_levels'+'.npy', LEVELS)
tmp_data = np.load(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod) + '_T'+'.npy')
relh_data = np.load(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_RH'+'.npy')
geoh_data = np.load(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_z'+'.npy')
o3m_data = np.load(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_o3_vmr'+'.npy')
clm_data = np.load(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_cloud_mr'+'.npy')
LEVELS = np.load(str(PATH)+ '/' + str(args.gfsdate[0:-2])+ '/' + str(args.gfsdate) + '/' + str(args.gfsdate)+str(args.gfscycle)+ '/' + str(args.lat) + '_N_' + str(args.lon) + '_E' + '/' + str(args.gfsdate)+str(args.gfscycle)+ '_' + str(args.lat) + '_N_' + str(args.lon) + '_E_' + str(args.altitude)+ 'm_'+ str(args.gfsprod)+'_levels'+'.npy')
Pbase = np.zeros(len(LEVELS))
z = np.zeros(len(LEVELS))
T = np.zeros(len(LEVELS))
o3_vmr = np.zeros(len(LEVELS))
RH = np.zeros(len(LEVELS))
cloud_mr = np.zeros(len(LEVELS))
if LEVELS[0] == 1000:
geoh_data = geoh_data[::-1]
tmp_data = tmp_data[::-1]
o3m_data = o3m_data[::-1]
relh_data = relh_data[::-1]
clm_data = clm_data[::-1]
LEVELS = LEVELS[::-1]
for i in np.arange(len(LEVELS)):
Pbase[i] = LEVELS[i]
T[i] = np.mean(tmp_data[i])
for i in np.arange(len(geoh_data)):
z[i] = np.mean(geoh_data[i])
for i in np.arange(len(o3m_data)):
o3_vmr[i] = np.mean(o3m_data[i])
for i in np.arange(len(relh_data)):
RH[i] = np.mean(relh_data[i])
for i in np.arange(len(clm_data)):
cloud_mr[i] = np.mean(clm_data[i])
#######################################################################################################################
# Print out the layer descriptions. On a layer, mixing ratios and
# RH are set to their averages over the two levels bounding the layer.
if (args.gfsprod == "anl"):
product_str = "analysis"
else:
product_str = args.gfsprod[1:] + " hour forecast"
print LAYER_HEADER.format(
args.gfsdate,
args.gfscycle,
product_str,
args.lat,
args.lon,
args.altitude)
for i in np.arange(len(LEVELS)):
if (z[i] > args.altitude):
print "layer"
print "Pbase {0:.1f} mbar # {1:.1f} m".format(Pbase[i], z[i])
print "Tbase {0:.1f} K".format(T[i])
print "column dry_air vmr"
if (i > 0):
o3_vmr_mid = 0.5 * ( o3_vmr[i-1] + o3_vmr[i])
RH_mid = 0.5 * ( RH[i-1] + RH[i])
cloud_mr_mid = 0.5 * (cloud_mr[i-1] + cloud_mr[i])
T_mid = 0.5 * ( T[i-1] + T[i])
else:
o3_vmr_mid = o3_vmr[i]
RH_mid = RH[i]
cloud_mr_mid = cloud_mr[i]
T_mid = T[i]
if (o3_vmr_mid > 0.0):
print "column o3 vmr {0:.3e}".format(o3_vmr_mid)
if (RH_mid > 0.0):
if (T_mid > H2O_SUPERCOOL_LIMIT):
print "column h2o RH {0:.2f}%".format(RH_mid)
else:
print "column h2o RHi {0:.2f}%".format(RH_mid)
if (cloud_mr_mid > 0.0):
# Convert cloud mixing ratio [kg / kg] to cloud total water
# across the layer [kg / m^2].
dP = PASCAL_ON_MBAR * (Pbase[i] - Pbase[i-1])
m = dP / G_STD
ctw = m * cloud_mr_mid
if ctw <= 0:
print ""
continue
if (T_mid > H2O_SUPERCOOL_LIMIT):
print "column lwp_abs_Rayleigh {0:.3e} kg*m^-2".format(ctw)
else:
print "column iwp_abs_Rayleigh {0:.3e} kg*m^-2".format(ctw)
print ""
# The base layer and base level of the model are special cases. First,
# we find the pressure and temperature of the base level by linearly
# interpolating (or extrapolating) log P and T in z.
if (i == 0):
print "User-specified altitude exceeds top GFS level"
exit()
if (z[i] == args.altitude): # exact coincidence with model level
exit()
u = (args.altitude - z[i-1]) / (z[i] - z[i-1])
logP_s = u * math.log(Pbase[i]) + (1.0 - u) * math.log(Pbase[i-1])
P_s = math.exp(logP_s)
T_s = u * T[i] + (1.0 - u) * T[i-1]
if P_s <= Pbase[i]:
exit()
# Other variables are interpolated or extrapolated linearly in P
# to the base level and clamped at zero.
u = (P_s - Pbase[i-1]) / (Pbase[i] - Pbase[i-1])
o3_vmr_s = u * o3_vmr[i] + (1.0 - u) * o3_vmr[i-1]
RH_s = u * RH[i] + (1.0 - u) * RH[i-1]
cloud_mr_s = u * cloud_mr[i] + (1.0 - u) * cloud_mr[i-1]
if (o3_vmr_s < 0.0):
o3_vmr_s = 0.0
if (RH_s < 0.0):
RH_s = 0.0
if (cloud_mr_s < 0.0):
cloud_mr_s = 0.0
o3_vmr_mid = 0.5 * ( o3_vmr[i-1] + o3_vmr_s)
RH_mid = 0.5 * ( RH[i-1] + RH_s)
cloud_mr_mid = 0.5 * (cloud_mr[i-1] + cloud_mr_s)
print "layer"
print "Pbase {0:.1f} mbar # {1:.1f} m".format(P_s, args.altitude)
print "Tbase {0:.1f} K".format(T_s)
print "column dry_air vmr"
if (o3_vmr_mid > 0.0):
print "column o3 vmr {0:.3e}".format(o3_vmr_mid)
if (RH_mid > 0.0):
if (T_mid > H2O_SUPERCOOL_LIMIT):
print "column h2o RH {0:.2f}%".format(RH_mid)
else:
print "column h2o RHi {0:.2f}%".format(RH_mid)
if (cloud_mr_mid > 0.0):
dP = PASCAL_ON_MBAR * (Pbase[i] - Pbase[i-1])
m = dP / G_STD
ctw = m * cloud_mr_mid
if (T_mid > H2O_SUPERCOOL_LIMIT):
print "column lwp_abs_Rayleigh {0:.3e} kg*m^-2".format(ctw)
else:
print "column iwp_abs_Rayleigh {0:.3e} kg*m^-2".format(ctw)
exit()