#!/usr/bin/env python
#'''
# Copyright 20152018 ECMWF.
#
# This software is licensed under the terms of the Apache Licence Version 2.0
# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0
#
# In applying this licence, ECMWF does not waive the privileges and immunities
granted to it by
# virtue of its status as an intergovernmental organisation
nor does it submit to any jurisdiction.
#
# **************************************************************************
# Function : compute_geopotential_on_ml
#
# Author (date) : Cristian Simarro (09/10/2015)
# modified: Cristian Simarro (20/03/2017) - migrated to eccodes
#
# Category : COMPUTATION
#
# OneLineDesc : Computes geopotential on model levels
#
# DescriptionXavi Abellan : Computes geopotential on model levels.
# (03/12/2018) - compatibilty with Python 3
Category : COMPUTATION
OneLineDesc : Computes geopotential on model levels
Description : Computes geopotential on model levels.
Based on code from Nils Wedi, the IFS documentation:
# https://software.ecmwf.int/wiki/display/IFS/CY41R1+Official+IFS+Documentation
# part III. Dynamics and numerical procedures
# optimised implementation by Dominique Lucas.
# ported to Python by Cristian Simarro
#
# Parameters : tq.grib - grib file with all the levelist
of t and q
# zlnsp.grib - grib file with levelist 1 for paramsof zt and lnsp
#q
zlnsp.grib -l grib file with levelist (optional)1 -for slashparams
'/' separated list of levelist to store in the output
# -o output (optional) - name of the output file (default='z_out.grib')
#
# Return Value : output (default='z_out.grib')
# z and lnsp
-l levelist (optional) - slash '/' separated A fieldsetlist of geopotentiallevelist
on model levels
#
# Dependencies : None
#
# Example Usage :
# python compute_geopotential_on_ml.py tq.grib zlnsp.grib
from numpy import *
import sys,math,os
import argparse
from eccodes importto *
store
def main(t_q,z_lnsp,out_name,levelist):
in the output
#some checks and information printing
print "Using as input files:\n ",t_q,z_lnsp
print "The result will be stored in:\n ",out_name
-o output (optional) - name of the output file
if levelist != "":
print "Will only store these levels: "+levelist
levelist_selected=levelist.split("/")
fout = open(out_name,'w')
ftmp = open(t_q)
total_messages=codes_count_in_file(ftmp)/2
ftmp.close()
Rd = 287.06
index_keys = ["date","time","shortName","level","step"]
values= {}
pv = {}
zlnsp = codes_index_new_from_file(z_lnsp,index_keys)
iidtq = default='z_out.grib')
Return Value : output (default='z_out.grib')
A fieldset of geopotential on model levels
Dependencies : None
Example Usage :
compute_geopotential_on_ml.py tq.grib zlnsp.grib
'''
from __future__ import print_function
import sys
import argparse
import numpy as np
from eccodes import (codes_index_new_from_file(t_q,index_keys)
, codes_index_get, codes_get,
#we need to get z and lnsp from the first level to do the calculations
codes_index_select, counter=0codes_new_from_index, codes_set,
for date in codes_index_get(zlnsp,'date'):
codes_index_select(zlnsp,'date',date)
codes_index_select(iidtq,'date',date)add_file, codes_get_array, codes_get_values,
for time in codes_index_get(zlnsp,'time'):
codes_index_release, codes_release, codes_indexset_select(zlnsp,'time',time)values,
codes_index_select(iidtq,'time',time)
codes_index_select(zlnsp,'level',1)
codes_index_select(zlnsp,'step',0)
codes_write)
R_D = 287.06
R_G = 9.80665
def parse_args():
''' Parse program arguments using ArgumentParser'''
parser = argparse.ArgumentParser(
description='Python tool to calculate the Z of the model levels')
parser.add_argument('-l', '--levelist', help='levelist to store',
codes_index_select(zlnsp,'shortName','z')
gid = codes_new_from_index(zlnsp default='')
parser.add_argument('-o', '--output', help='name of the
output file',
# surface geopotential
values["z"] = codes_get_values(giddefault='z_out.grib')
parser.add_argument('t_q', metavar='tq.grib', type=str,
z_h = values["z"]
pv help= codes_get_array(gid,'pv')('grib file with temperature(t) and humidity(q)',
levelSizeNV = codes_get(gid,'NV',int)/2 -1
'for the model levels'))
codesparser.add_release(gid)
argument('z_lnsp', metavar='zlnsp.grib', type=str,
for step in codes_index_get(iidtq,'step'): help=('grib file with geopotential(z) and Logarithm',
z_h = values["z"]
'of surface pressure(lnsp) for codes_index_select(iidtq,'step',stepthe ml=1'))
args = parser.parse_args()
if args.levelist codes_index_select(zlnsp,'step',step)== 'all':
args.levelist = ''
return for shortName in ["lnsp"]args
def main():
'''Main function'''
args = parse_args()
print('Arguments: %s' % codes_index_select(zlnsp,'shortName',shortName)", ".join(
['%s: %s' % (k, v) for k, v in vars(args).items()]))
gid fout = codes_new_from_index(zlnspopen(args.output, 'wb')
index_keys = ['date', 'time', 'shortName', 'level', 'step']
idx = codes_index_new_from_file(args.z_lnsp, index_keys)
if codes_get(gid,"gridType",str) == "sh"_index_add_file(idx, args.t_q)
if 'u_v' in args:
codes_index_add_file(idx, args.u_v)
# iterate date
for date print(sys.argv[0]+' [ERROR] fields must be gridded, not spectral'in codes_index_get(idx, 'date'):
codes_index_select(idx, 'date', date)
# iterate step
for time in sys.exit(1)codes_index_get(idx, 'time'):
codes_index_select(idx, 'time', time)
values[shortName] = codesget_getinitial_values(gididx, keep_sample=True)
if 'height' in args:
pv = codes_get_array(gid,'pv')
values['height'] = args.height
levelSizeNV = codes_get(gid,'NV',int)/2 -1
values['gh'] = args.height * R_G + values['z']
codes_release(gid)
if 'levelist' in args:
# surface pressurevalues['levelist'] = args.levelist
# iterate step all sp = exp(values["lnsp"]but geopotential z which is always step 0 (an)
for step in codes_index_get(idx, 'step'):
# get the coefficients for computing the pressures
codes_index_select(idx, 'step', step)
# how many levels are we computing?
# surface pressure
codes_index_select(iidtq,'shortName',"t"values['sp'] = get_surface_pressure(idx)
levelSize=max(codes_index_get(iidtq,"level",int))production_step(idx, values, fout)
try:
if levelSize != levelSizeNV:
codes_release(values['sample'])
except KeyError:
print(sys.argv[0]+' [WARN] total levels should be: '+str(levelSizeNV)+' but it is '+str(levelSize))
A = pv[0:levelSize+1]
B = pv[levelSize+1:]
Ph_levplusone = A[levelSize] + (B[levelSize]*sp)
# We want to integrate up into the atmosphere, starting at the ground
# so we start at the lowest level (highest number) and keep
pass
codes_index_release(idx)
fout.close()
def get_initial_values(idx, keep_sample=False):
'''Get the values of surface z, pv and number of levels '''
codes_index_select(idx, 'level', 1)
codes_index_select(idx, 'step', 0)
codes_index_select(idx, 'shortName', 'z')
gid = codes_new_from_index(idx)
values = {}
# surface geopotential
values['z'] = codes_get_values(gid)
values['pv'] = codes_get_array(gid, 'pv')
values['nlevels'] = codes_get(gid, 'NV', int) // 2 - 1
check_max_level(idx, values)
if keep_sample:
values['sample'] = gid
# accumulating the height as we go. else:
codes_release(gid)
return # See the IFS documentationvalues
def check_max_level(idx, values):
'''Make sure we have all the levels required'''
# https://software.ecmwf.int/wiki/display/IFS/CY41R1+Official+IFS+Documentation
how many levels are we computing?
max_level = max(codes_index_get(idx, 'level', int))
if # part IIImax_level != values['nlevels']:
print('%s [WARN] total levels should be: %d but #it Foris speed%d' and%
file I/O, we perform the computations with numpy vectors instead
(sys.argv[0], values['nlevels'], max_level),
# of fieldsetsfile=sys.stderr)
values['nlevels'] = max_level
def get_surface_pressure(idx):
'''Get the for lev in list(reversed(range(1,levelSize+1))):
surface pressure for date-time-step'''
codes_index_select(idx, 'level', 1)
codes_index_select(idx, 'shortName', 'lnsp')
gid = codes_new_from_index(idx)
if codes_get(gid, 'gridType', str) == 'sh':
# select the levelist and retrieve the vaules of t and q
print('%s [ERROR] fields must be gridded, not spectral' % sys.argv[0],
file=sys.stderr)
# t_level: values for t sys.exit(1)
# surface pressure
sfc_p = np.exp(codes_get_values(gid))
codes_release(gid)
#return q_level: values for qsfc_p
def get_ph_levs(values, level):
'''Return the presure at a given level and the next'''
a_coef codes_index_select(iidtq,'level',lev)
= values['pv'][0:values['nlevels'] + 1]
b_coef = values['pv'][values['nlevels'] + 1:]
ph_lev = a_coef[level - 1] + codes_index_select(iidtq,'shortName',"t"(b_coef[level - 1] * values['sp'])
ph_levplusone = a_coef[level] + (b_coef[level] * values['sp'])
return gid = codes_new_from_index(iidtq)ph_lev, ph_levplusone
def compute_z_level(idx, lev, values, z_h):
'''Compute z at half & full level for the given level, based on t/q/sp'''
t_level = codes_get_values(gid)
# select the levelist and retrieve the vaules of t and q
# t_level: values for t
# #gidq_outlevel: willvalues befor usedq
as output, cloning to get the attributes codes_index_select(idx, 'level', lev)
codes_index_select(idx, 'shortName', 't')
gid = codes_new_from_index(idx)
gid_outt_level = codes_cloneget_values(gid)
codes_release(gid)
codes_index_select(iidtqidx, 'shortName'," 'q"')
gid = codes_new_from_index(iidtqidx)
q_level = codes_get_values(gid)
codes_release(gid)
# compute moist temperature
t_level = t_level * (1. + 0.609133 # compute moist temperature* q_level)
# compute the pressures (on half-levels)
t_levelph_lev, ph_levplusone = t_level * (1.+0.609133*q_level)
get_ph_levs(values, lev)
if lev == 1:
dlog_p = np.log(ph_levplusone / 0.1)
# compute thealpha pressures= (on half-levels)np.log(2)
else:
dlog_p = np.log(ph_levplusone / ph_lev)
Ph_levalpha = A[lev-1]. +- (B[lev-1](ph_lev / (ph_levplusone - ph_lev)) * spdlog_p)
t_level = t_level * R_D
# z_f is the geopotential of this if lev == 1:full level
# integrate from previous (lower) half-level z_h to the
# full level
z_f = dlogPz_h =+ log(Ph_levplusone/0.1)t_level * alpha)
# z_h is the geopotential of 'half-levels'
# integrate z_h to next half level
alphaz_h = log(2)
z_h + (t_level * dlog_p)
return z_h, z_f
def production_step(idx, elsevalues, fout):
'''Compute z at half & full level for the given level, based dlogP = log(Ph_levplusone/Ph_lev)
dP = Ph_levplusone-Ph_lev
alpha = 1. - ((Ph_lev/dP)*dlogP)
TRd = t_level*Rd
# z_f is the geopotential of this full level
# integrate from previous (lower) half-level z_h to the full level
z_f = z_h + (TRd*alpha)
# z_h is the geopotential of 'half-levels'
# integrate z_h to next half level
z_h=z_h+(TRd*dlogP)
Ph_levplusone = Ph_lev
# store the result (z_f) in a field and add to the output fieldset
# (add it to the front, not the end, because we are going 'backwards'
# through the fields)
if levelist == "" or str(lev) in levelist_selected:
codes_set(gid_out,"paramId",129)
codes_set(gid_out,'generatingProcessIdentifier',128)
codes_set(gid_out,'level', lev)
#codes_set(gid_out,"bitsPerValue",24)
codes_set_values(gid_out,z_f)
codes_write(gid_out,fout)
counter += 1
if counter >= int((total_messages+1)/20):
sys.stdout.write('.')
sys.stdout.flush()
counter=0
codes_release(gid_out)
fout.close()
print("Done")
if __name__ == "__main__":
request_date=0
request_time=0
levelist = ""
out_name = 'z_out.grib'
parser = argparse.ArgumentParser(
description='Python tool to calculate the Z of the model levels')
parser.add_argument("-l","--levelist", help="levelist to store")
parser.add_argument("-o","--output", help="name of the output file")
parser.add_argument('t_q', metavar='tq.grib', type=str,
help='grib file with temperature(t) and humidity(q) for the model levels')
parser.add_argument('z_lnsp', metavar='zlnsp.grib', type=str,
help='grib file with geopotential(z) and Logarithm of surface pressure(lnsp) for the ml=1')
args = parser.parse_args()
for fname in (args.t_q,args.z_lnsp):
if not os.path.isfile(fname):on t/q/sp'''
# We want to integrate up into the atmosphere, starting at the
# ground so we start at the lowest level (highest number) and
# keep accumulating the height as we go.
# See the IFS documentation, part III
# For speed and file I/O, we perform the computations with
# numpy vectors instead of fieldsets.
z_h = values['z']
for lev in list(reversed(list(range(1, values['nlevels'] + 1)))):
z_h, z_f = compute_z_level(idx, lev, values, z_h)
# store the print "[ERROR] file %s does not exist" %(fname)result (z_f) in a field and add to the output
if values['levelist'] == '' or sys.exitstr(1lev)
in values['levelist']:
if args.levelist:
if args.levelist != "all": codes_set(values['sample'], 'level', lev)
levelist=args.levelistcodes_set_values(values['sample'], z_f)
if args.output:
out_name=args.output
#calling main functioncodes_write(values['sample'], fout)
if __name__ == '__main__':
main(args.t_q,args.z_lnsp,out_name,levelist))
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