A collection of diagnostic and interpolation routines for use with output from the Weather Research and Forecasting (WRF-ARW) Model.
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from __future__ import (absolute_import, division, print_function,
unicode_literals)
import numpy as n
#from .extension import computectt, computetk
from .extension import _ctt, _tk
from .constants import Constants, ConversionFactors
from .destag import destagger
from .decorators import convert_units
from .metadecorators import copy_and_set_metadata
from .util import extract_vars
@copy_and_set_metadata(copy_varname="T", name="ctt",
remove_dims=("bottom_top",),
description="cloud top temperature",
MemoryOrder="XY")
@convert_units("temp", "c")
def get_ctt(wrfin, timeidx=0, method="cat",
squeeze=True, cache=None, meta=True, _key=None,
units="degC"):
"""Return the cloud top temperature.
This functions extracts the necessary variables from the NetCDF file
object in order to perform the calculation.
Args:
wrfin (:class:`netCDF4.Dataset`, :class:`Nio.NioFile`, or an \
iterable): WRF-ARW NetCDF
data as a :class:`netCDF4.Dataset`, :class:`Nio.NioFile`
or an iterable sequence of the aforementioned types.
timeidx (:obj:`int` or :data:`wrf.ALL_TIMES`, optional): The
desired time index. This value can be a positive integer,
negative integer, or
:data:`wrf.ALL_TIMES` (an alias for None) to return
all times in the file or sequence. The default is 0.
method (:obj:`str`, optional): The aggregation method to use for
sequences. Must be either 'cat' or 'join'.
'cat' combines the data along the Time dimension.
'join' creates a new dimension for the file index.
The default is 'cat'.
squeeze (:obj:`bool`, optional): Set to False to prevent dimensions
with a size of 1 from being automatically removed from the shape
of the output. Default is True.
cache (:obj:`dict`, optional): A dictionary of (varname, ndarray)
that can be used to supply pre-extracted NetCDF variables to the
computational routines. It is primarily used for internal
purposes, but can also be used to improve performance by
eliminating the need to repeatedly extract the same variables
used in multiple diagnostics calculations, particularly when using
large sequences of files.
Default is None.
meta (:obj:`bool`, optional): Set to False to disable metadata and
return :class:`numpy.ndarray` instead of
:class:`xarray.DataArray`. Default is True.
_key (:obj:`int`, optional): A caching key. This is used for internal
purposes only. Default is None.
units (:obj:`str`): The desired units. Refer to the :meth:`getvar`
product table for a list of available units for 'ctt'. Default
is 'degC'.
Returns:
:class:`xarray.DataArray` or :class:`numpy.ndarray`: The
cloud top temperature.
If xarray is enabled and the *meta* parameter is True, then the result
will be a :class:`xarray.DataArray` object. Otherwise, the result will
be a :class:`numpy.ndarray` object with no metadata.
"""
varnames = ("T", "P", "PB", "PH", "PHB", "HGT", "QVAPOR")
ncvars = extract_vars(wrfin, timeidx, varnames, method, squeeze, cache,
meta=False, _key=_key)
t = ncvars["T"]
p = ncvars["P"]
pb = ncvars["PB"]
ph = ncvars["PH"]
phb = ncvars["PHB"]
ter = ncvars["HGT"]
qv = ncvars["QVAPOR"] * 1000.0 # g/kg
haveqci = 1
try:
icevars = extract_vars(wrfin, timeidx, "QICE",
method, squeeze, cache, meta=False,
_key=_key)
except KeyError:
qice = n.zeros(qv.shape, qv.dtype)
haveqci = 0
else:
qice = icevars["QICE"] * 1000.0 #g/kg
try:
cldvars = extract_vars(wrfin, timeidx, "QCLOUD",
method, squeeze, cache, meta=False,
_key=_key)
except KeyError:
raise RuntimeError("'QCLOUD' not found in NetCDF file")
else:
qcld = cldvars["QCLOUD"] * 1000.0 #g/kg
full_p = p + pb
p_hpa = full_p * ConversionFactors.PA_TO_HPA
full_t = t + Constants.T_BASE
tk = _tk(full_p, full_t)
geopt = ph + phb
geopt_unstag = destagger(geopt, -3)
ght = geopt_unstag / Constants.G
ctt = _ctt(p_hpa, tk, qice, qcld, qv, ght, ter, haveqci)
return ctt