def eqvlat_hemispheric(ylat, vort, area, nlat_s=None, n_points=None,
planet_radius=6.378e+6):
"""
Compute equivalent latitude in a hemispheric domain.
Parameters
----------
ylat : numpy.array
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
vort : numpy.ndarray
2-d numpy array of vorticity values; dimension = (nlat, nlon).
area : numpy.ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
nlat_s : int, default None
The index of grid point that defines the extent of hemispheric domain from the pole. If input as None, it will be initialize as nlat // 2.
n_points : int, default None
Analysis resolution to calculate equivalent latitude. If input as None, it will be initialized as *nlat_s*.
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
Returns
-------
q_part : numpy.ndarray
1-d numpy array of value Q(y) where latitude y is given by ylat; dimension = (nlat).
"""
from hn2016_falwa import basis
nlat = vort.shape[0]
qref = np.zeros(nlat)
if nlat_s is None:
nlat_s = nlat // 2
if n_points is None:
n_points = nlat_s
# --- Southern Hemisphere ---
qref1, _ = basis.eqvlat(ylat[:nlat_s], vort[:nlat_s, :], area[:nlat_s, :],
n_points, planet_radius=planet_radius)
qref[:nlat_s] = qref1
# --- Northern Hemisphere ---
vort2 = -vort[::-1, :]
qref2, _ = basis.eqvlat(ylat[:nlat_s], vort2[:nlat_s, :], area[:nlat_s, :],
n_points, planet_radius=planet_radius)
qref[-nlat_s:] = qref2[::-1]
return qref
def equivalent_latitudes(self):
"""
Compute equivalent latitude with the *pv_field* stored in the object.
:returns: an numpy array with dimension (nlat) of equivalent latitude array.
:example:
>>> barofield1 = BarotropicField(xlon, ylat, pv_field=abs_vorticity)
>>> eqv_lat = barofield1.equivalent_latitudes()
"""
from hn2016_falwa import basis
pv_field = self.pv_field
area = self.area
ylat = self.ylat
planet_radius = self.planet_radius
self.eqvlat, dummy = basis.eqvlat(ylat,
pv_field,
area,
self.n_partitions,
planet_radius=planet_radius)
return self.eqvlat
def test_eqvlat(self):
'''
To test whether the eqvlat function in basis.py produce a reference state of vorticity non-decreasing with latitude, given a random vorticity field.
'''
q_part1, vgrad = basis.eqvlat(
self.ylat, self.vort, self.area, self.nlat,
planet_radius=self.planet_radius,
vgrad=self.dummy_vgrad
)
q_part2, _ = basis.eqvlat(
self.ylat, self.vort, self.area, self.nlat,
planet_radius=self.planet_radius,
vgrad=None
)
self.assertTrue(np.all(np.diff(q_part1) >= 0.))
self.assertEqual(q_part1.tolist(), q_part2.tolist())
self.assertTrue(vgrad is not None)
self.assertEqual(vgrad.shape, q_part1.shape)
def _compute_eqvlat(self):
"""
Private function. Compute equivalent latitude if it has not been computed yet.
"""
self.eqvlat, _ = basis.eqvlat(self.ylat,
self.pv_field,
self.area,
self.n_partitions,
planet_radius=self.planet_radius)
return self.eqvlat
def test_eqvlat():
'''
To test whether the eqvlat function in basis.py produce a reference state of vorticity non-decreasing with latitude, given a random vorticity field.
'''
q_part1, vgrad = basis.eqvlat(ylat,
vort,
area,
nlat,
planet_radius=EARTH_RADIUS,
vgrad=dummy_vgrad)
q_part2, _ = basis.eqvlat(ylat,
vort,
area,
nlat,
planet_radius=EARTH_RADIUS,
vgrad=None)
assert np.all(np.diff(q_part1) >= 0.)
assert q_part1.tolist() == q_part2.tolist()
assert vgrad is not None
assert vgrad.shape == q_part1.shape
def barotropic_eqlat_lwa(ylat,
vort,
area,
dmu,
n_points,
planet_radius=6.378e+6):
"""
Compute equivalent latitude and wave activity on a barotropic sphere.
Parameters
----------
ylat : sequence or array_like
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
vort : ndarray
2-d numpy array of vorticity values; dimension = (nlat, nlon).
area : ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
dmu: sequence or array_like
1-d numpy array of latitudinal differential length element (e.g. dmu = cos(lat) d(lat)). Size = nlat.
n_points : int, default None
Analysis resolution to calculate equivalent latitude. If input as None, it will be initialized as *nlat*.
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
Returns
-------
qref : ndarray
1-d numpy array of value Q(y) where latitude y is given by ylat; dimension = (nlat).
lwa_result : ndarray
2-d numpy array of local wave activity values;
dimension = [nlat_s x nlon]
"""
from hn2016_falwa import basis
nlat = vort.shape[0]
nlon = vort.shape[1]
if n_points is None:
n_points = nlat
qref, dummy = basis.eqvlat(ylat,
vort,
area,
n_points,
planet_radius=planet_radius)
lwa_result, dummy = basis.lwa(nlon, nlat, vort, qref, dmu)
return qref, lwa_result
def barotropic_eqlat_lwa(ylat, vort, area, dmu, n_points,
planet_radius=6.378e+6):
"""
Compute equivalent latitude and wave activity on a barotropic sphere.
Parameters
----------
ylat : numpy.array
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
vort : numpy.ndarray
2-d numpy array of vorticity values; dimension = (nlat, nlon).
area : numpy.ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
dmu: numpy.array
1-d numpy array of latitudinal differential length element (e.g. dmu = planet_radius * cos(lat) d(lat)). Size = nlat.
n_points : int, default None
Analysis resolution to calculate equivalent latitude. If input as None, it will be initialized as *nlat*.
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
Returns
-------
qref : numpy.array
1-d numpy array of value Q(y) where latitude y is given by ylat; dimension = (nlat).
lwa_result : numpy.ndarray
2-d numpy array of local wave activity values;
dimension = [nlat_s x nlon]
"""
from hn2016_falwa import basis
nlat = vort.shape[0]
nlon = vort.shape[1]
if n_points is None:
n_points = nlat
qref, dummy = basis.eqvlat(ylat, vort, area, n_points,
planet_radius=planet_radius)
lwa_result, dummy = basis.lwa(nlon, nlat, vort, qref, dmu)
return qref, lwa_result
def equivalent_latitudes(self):
"""
Compute equivalent latitude with the *pv_field* stored in the object.
Return
----------
An numpy array with dimension (nlat) of equivalent latitude array.
Example
----------
>>> barofield1 = BarotropicField(xlon, ylat, pv_field=abs_vorticity)
>>> eqv_lat = barofield1.equivalent_latitudes()
"""
from hn2016_falwa import basis
self.eqvlat, dummy = basis.eqvlat(
self.ylat, self.pv_field, self.area, self.n_partitions,
planet_radius=self.planet_radius
)
return self.eqvlat
def eqvlat_hemispheric(ylat,
vort,
area,
nlat_s=None,
n_points=None,
planet_radius=6.378e+6):
"""
Compute equivalent latitude in a hemispheric domain.
Parameters
----------
ylat : sequence or array_like
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
vort : ndarray
2-d numpy array of vorticity values; dimension = (nlat, nlon).
area : ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
nlat_s : int, default None
The index of grid point that defines the extent of hemispheric domain from the pole. If input as None, it will be initialize as int(nlat/2).
n_points : int, default None
Analysis resolution to calculate equivalent latitude. If input as None, it will be initialized as *nlat_s*.
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
Returns
-------
q_part : ndarray
1-d numpy array of value Q(y) where latitude y is given by ylat; dimension = (nlat).
"""
from hn2016_falwa import basis
nlat = vort.shape[0]
qref = np.zeros(nlat)
brac = np.zeros(nlat)
if nlat_s is None:
nlat_s = int(nlat / 2)
if n_points is None:
n_points = nlat_s
# --- Southern Hemisphere ---
qref1, dummy = basis.eqvlat(ylat[:nlat_s],
vort[:nlat_s, :],
area[:nlat_s, :],
n_points,
planet_radius=planet_radius)
qref[:nlat_s] = qref1
# --- Northern Hemisphere ---
vort2 = -vort[::
-1, :] # Added the minus sign, but gotta see if NL_North is affected
qref2, dummy = basis.eqvlat(ylat[:nlat_s],
vort2[:nlat_s, :],
area[:nlat_s, :],
n_points,
planet_radius=planet_radius)
qref[-nlat_s:] = qref2[::-1]
return qref
def theta_lwa(ylat,
theta,
area,
dmu,
nlat_s=None,
n_points=None,
planet_radius=6.378e+6):
"""
Compute the surface wave activity *B* based on surface potential temperature.
See Nakamura and Solomon (2010a) for details.
Parameters
----------
ylat : sequence or array_like
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
theta : ndarray
2-d numpy array of surface potential temperature field; dimension = (nlat, nlon).
area : ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
dmu: sequence or array_like
1-d numpy array of latitudinal differential length element (e.g. dmu = cos(lat) d(lat)). Size = nlat.
nlat_s : int, default None
The index of grid point that defines the extent of hemispheric domain from the pole. If input as None, it will be initialize as int(nlat/2).
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
Returns
-------
qref : sequence or array_like
1-d numpy array of value reference potential temperature *Theta(y)* approximated by box counting method, where latitude y is given by ylat; dimension = (nlat).
lwa_result : ndarray
2-d numpy array of local surface wave activity values; dimension = (nlat, nlon).
"""
from hn2016_falwa import basis
nlat = theta.shape[0]
nlon = theta.shape[1]
if nlat_s == None:
nlat_s = nlat / 2
if n_points == None:
n_points = nlat_s
qref = np.zeros(nlat)
lwa_result = np.zeros((nlat, nlon))
# --- southern Hemisphere ---
qref[:nlat_s], brac = basis.eqvlat(ylat[:nlat_s],
theta[:nlat_s, :],
area[:nlat_s, :],
n_points,
planet_radius=planet_radius)
#qref1 = eqvlat(ylat[:nlat_s],theta[:nlat_s,:],area[:nlat_s,:],nlat_s,planet_radius=6.378e+6)
# qref[:nlat_s] = qref1
# lwa_south = lwa(nlon,nlat_s,theta[:nlat_s,:],qref1,dmu[:nlat_s])
lwa_result[:nlat_s, :], dummy = basis.lwa(nlon, nlat_s, theta[:nlat_s, :],
qref[:nlat_s], dmu[:nlat_s])
# lwa_result[:nlat_s,:] = lwa_south
# --- northern Hemisphere ---
theta2 = theta[::
-1, :] # Added the minus sign, but gotta see if NL_north is affected
# qref2 = eqvlat(ylat[:nlat_s],theta2[:nlat_s,:],area[:nlat_s,:],nlat_s,planet_radius=6.378e+6)
qref2, brac = basis.eqvlat(ylat[:nlat_s],
theta2[:nlat_s, :],
area[:nlat_s, :],
n_points,
planet_radius=planet_radius)
qref[-nlat_s:] = qref2[::-1]
# lwa_north = lwa(nlon,nlat_s,theta2[:nlat_s,:],qref2,dmu[:nlat_s])
lwa_result[-nlat_s:, :], dummy = basis.lwa(nlon, nlat_s,
theta[-nlat_s:, :],
qref[-nlat_s:], dmu[-nlat_s:])
# lwa_result[-nlat_s:,:] = lwa_north[::-1,:]
return qref, lwa_result
def qgpv_eqlat_lwa_options(ylat,
vort,
area,
dmu,
nlat_s=None,
n_points=None,
vgrad=None,
ncforce=None,
planet_radius=6.378e+6):
"""
Compute equivalent latitutde *qref*, local wave activity *lwa_result* and
non-conservative force on wave activity *bigsigma_result* based on Quasi-
geostrophic potential vorticity field *vort* at a pressure level as
outlined in Huang and Nakamura (2017).
Parameters
----------
ylat : sequence or array_like
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
vort : ndarray
2-d numpy array of Quasi-geostrophic potential vorticity field; dimension = (nlat, nlon).
ncforce: ndarray
2-d numpy array of non-conservative force field (i.e. theta in NZ10(a) in equation (23a) and (23b));
dimension = (nlat, nlon).
area : ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
dmu: sequence or array_like
1-d numpy array of latitudinal differential length element (e.g. dmu = cos(lat) d(lat)). Size = nlat.
nlat_s : int, default None
The index of grid point that defines the extent of hemispheric domain from the pole. If input as None, it will be initialize as int(nlat/2).
n_points : int, default None
Analysis resolution to calculate equivalent latitude. If input as None, it will be initialized as *nlat_s*.
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
Returns
-------
return_dict : dictionary
A dictionary that consist of the 4 computed outputs listed below.
(1) qref : ndarray
1-d numpy array of value Q(y) where latitude y is given by ylat; dimension = (nlat).
(2) brac_result: ndarray
1-d numpy array of <...>_Q(y) in NZ10 where latitude y is given by ylat; dimension = (nlat).
(3) lwa_result : ndarray
2-d numpy array of local wave activity values; dimension = (nlat, nlon).
(4) bigsigma_result: ndarray
2-d numpy array of non-conservative force contribution value; dimension = (nlat, nlon).
"""
from hn2016_falwa import basis
nlat = vort.shape[0]
nlon = vort.shape[1]
if nlat_s is None:
nlat_s = int(nlat / 2)
if n_points is None:
n_points = nlat_s
qref = np.zeros(nlat)
lwa_result = np.zeros((nlat, nlon))
if ncforce is not None:
bigsigma_result = np.zeros((nlat, nlon))
if vgrad is not None:
brac_result = np.zeros(nlat)
# --- Southern Hemisphere ---
if vgrad is None:
qref1, brac = basis.eqvlat(ylat[:nlat_s],
vort[:nlat_s, :],
area[:nlat_s, :],
n_points,
planet_radius=planet_radius)
else:
qref1, brac = basis.eqvlat(ylat[:nlat_s],
vort[:nlat_s, :],
area[:nlat_s, :],
n_points,
planet_radius=planet_radius,
vgrad=vgrad[:nlat_s, :])
qref[:nlat_s] = qref1
if vgrad is not None:
brac_result[:nlat_s] = brac
if ncforce is not None:
lwa_result[:nlat_s, :], bigsigma_result[:nlat_s, :] = basis.lwa(
nlon,
nlat_s,
vort[:nlat_s, :],
qref1,
dmu[:nlat_s],
ncforce=ncforce[:nlat_s, :])
else:
lwa_result[:nlat_s, :], dummy = basis.lwa(nlon, nlat_s,
vort[:nlat_s, :], qref1,
dmu[:nlat_s])
# --- Northern Hemisphere ---
vort2 = -vort[::
-1, :] # Added the minus sign, but gotta see if NL_North is affected
if vgrad is None:
qref2, brac = basis.eqvlat(ylat[:nlat_s],
vort2[:nlat_s, :],
area[:nlat_s, :],
n_points,
planet_radius=planet_radius)
else:
vgrad2 = -vgrad[::-1, :] # Is this correct?
qref2, brac = basis.eqvlat(ylat[:nlat_s],
vort2[:nlat_s, :],
area[:nlat_s, :],
n_points,
planet_radius=planet_radius,
vgrad=vgrad2[:nlat_s, :])
qref[-nlat_s:] = -qref2[::-1]
if vgrad is not None:
brac_result[-nlat_s:] = -brac[::-1]
if ncforce is not None:
lwa_result[-nlat_s:, :], bigsigma_result[-nlat_s:, :] = basis.lwa(
nlon,
nlat_s,
vort[-nlat_s:, :],
qref[-nlat_s:],
dmu[-nlat_s:],
ncforce=ncforce[-nlat_s:, :])
else:
lwa_result[-nlat_s:, :], dummy = basis.lwa(nlon, nlat_s,
vort[-nlat_s:, :],
qref[-nlat_s:],
dmu[-nlat_s:])
# Return things as dictionary
return_dict = dict()
return_dict['qref'] = qref
return_dict['lwa_result'] = lwa_result
if vgrad is not None:
return_dict['brac_result'] = brac_result
if ncforce is not None:
return_dict['bigsigma_result'] = bigsigma_result
return return_dict
def qgpv_eqlat_lwa(ylat,
vort,
area,
dmu,
nlat_s=None,
n_points=None,
planet_radius=6.378e+6):
"""
Compute equivalent latitutde *qref* and local wave activity *lwa_result* based
on Quasi-geostrophic potential vorticity field *vort* at a pressure level as
outlined in Huang and Nakamura (2017).
Parameters
----------
ylat : sequence or array_like
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
vort : ndarray
2-d numpy array of Quasi-geostrophic potential vorticity field; dimension = (nlat, nlon).
area : ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
dmu: sequence or array_like
1-d numpy array of latitudinal differential length element (e.g. dmu = cos(lat) d(lat)). Size = nlat.
nlat_s : int, default None
The index of grid point that defines the extent of hemispheric domain from the pole. If input as None, it will be initialize as int(nlat/2).
n_points : int, default None
Analysis resolution to calculate equivalent latitude. If input as None, it will be initialized as *nlat_s*.
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
Returns
-------
qref : ndarray
1-d numpy array of value Q(y) where latitude y is given by ylat; dimension = (nlat).
lwa_result : ndarray
2-d numpy array of local wave activity values;
dimension = [nlat_s x nlon]
"""
from hn2016_falwa import basis
nlat = vort.shape[0]
nlon = vort.shape[1]
if nlat_s is None:
nlat_s = int(nlat / 2)
if n_points is None:
n_points = nlat_s
qref = np.zeros(nlat)
lwa_result = np.zeros((nlat, nlon))
# --- Southern Hemisphere ---
qref1, dummy = basis.eqvlat(ylat[:nlat_s],
vort[:nlat_s, :],
area[:nlat_s, :],
n_points,
planet_radius=planet_radius)
qref[:nlat_s] = qref1
lwa_result[:nlat_s, :], dummy = basis.lwa(nlon, nlat_s, vort[:nlat_s, :],
qref1, dmu[:nlat_s])
# --- Northern Hemisphere ---
vort2 = -vort[::
-1, :] # Added the minus sign, but gotta see if NL_North is affected
qref2, dummy = basis.eqvlat(ylat[:nlat_s],
vort2[:nlat_s, :],
area[:nlat_s, :],
n_points,
planet_radius=planet_radius)
qref[-nlat_s:] = -qref2[::-1]
lwa_result[-nlat_s:, :], dummy = basis.lwa(nlon, nlat_s, vort[-nlat_s:, :],
qref[-nlat_s:], dmu[-nlat_s:])
return qref, lwa_result
def theta_lwa(ylat,theta,area,dmu,nlat_s=None,n_points=None,planet_radius=6.378e+6):
"""
Compute the surface wave activity *B* based on surface potential temperature.
See Nakamura and Solomon (2010a) for details.
Parameters
----------
ylat : numpy.array
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
theta : numpy.ndarray
2-d numpy array of surface potential temperature field; dimension = (nlat, nlon).
area : numpy.ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
dmu: numpy.array
1-d numpy array of latitudinal differential length element (e.g. dmu = planet_radius * cos(lat) d(lat)). Size = nlat.
nlat_s : int, default None
The index of grid point that defines the extent of hemispheric domain from the pole. If input as None, it will be initialize as nlat // 2.
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
Returns
-------
qref : numpy.array
1-d numpy array of value reference potential temperature *Theta(y)* approximated by box counting method, where latitude y is given by ylat; dimension = (nlat).
lwa_result : numpy.ndarray
2-d numpy array of local surface wave activity values; dimension = (nlat, nlon).
"""
from hn2016_falwa import basis
nlat = theta.shape[0]
nlon = theta.shape[1]
if nlat_s is None:
nlat_s = nlat // 2
if n_points is None:
n_points = nlat_s
qref = np.zeros(nlat)
lwa_result = np.zeros((nlat, nlon))
# --- southern Hemisphere ---
qref[:nlat_s], brac = basis.eqvlat(ylat[:nlat_s], theta[:nlat_s, :],
area[:nlat_s, :], n_points,
planet_radius=planet_radius)
#qref1 = eqvlat(ylat[:nlat_s],theta[:nlat_s,:],area[:nlat_s,:],nlat_s,planet_radius=6.378e+6)
# qref[:nlat_s] = qref1
# lwa_south = lwa(nlon,nlat_s,theta[:nlat_s,:],qref1,dmu[:nlat_s])
lwa_result[:nlat_s, :], dummy = basis.lwa(nlon, nlat_s, theta[:nlat_s, :],
qref[:nlat_s], dmu[:nlat_s])
# lwa_result[:nlat_s,:] = lwa_south
# --- northern Hemisphere ---
theta2 = theta[::-1, :]
# Added the minus sign, but gotta see if NL_north is affected
# qref2 = eqvlat(ylat[:nlat_s],theta2[:nlat_s,:],area[:nlat_s,:],nlat_s,planet_radius=6.378e+6)
qref2, brac = basis.eqvlat(ylat[:nlat_s], theta2[:nlat_s, :],
area[:nlat_s, :],
n_points, planet_radius=planet_radius)
qref[-nlat_s:] = qref2[::-1]
# lwa_north = lwa(nlon,nlat_s,theta2[:nlat_s,:],qref2,dmu[:nlat_s])
lwa_result[-nlat_s:, :], dummy = basis.lwa(nlon, nlat_s,
theta[-nlat_s:, :],
qref[-nlat_s:],
dmu[-nlat_s:])
# lwa_result[-nlat_s:,:] = lwa_north[::-1,:]
return qref, lwa_result
def qgpv_eqlat_lwa_options(ylat, vort, area, dmu, nlat_s=None,
n_points=None, vgrad=None, ncforce=None,
planet_radius=6.378e+6):
"""
Compute equivalent latitutde *qref*, local wave activity *lwa_result* and
non-conservative force on wave activity *capsigma* based on Quasi-
geostrophic potential vorticity field *vort* at a pressure level as
outlined in Huang and Nakamura (2017).
Parameters
----------
ylat : numpy.array
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
vort : numpy.ndarray
2-d numpy array of Quasi-geostrophic potential vorticity field; dimension = (nlat, nlon).
ncforce: numpy.ndarray
2-d numpy array of non-conservative force field (i.e. theta in NZ10(a) in equation (23a) and (23b));
dimension = (nlat, nlon).
area : numpy.ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
dmu: numpy.array
1-d numpy array of latitudinal differential length element (e.g. dmu = planet_radius * cos(lat) d(lat)). Size = nlat.
nlat_s : int, default None
The index of grid point that defines the extent of hemispheric domain from the pole. If input as None, it will be initialize as nlat // 2.
n_points : int, default None
Analysis resolution to calculate equivalent latitude. If input as None, it will be initialized as *nlat_s*.
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
Returns
-------
return_dict : dictionary
A dictionary that consist of the 4 computed outputs listed below.
(1) qref : numpy.ndarray
1-d numpy array of value Q(y) where latitude y is given by ylat; dimension = (nlat).
(2) brac_result: numpy.ndarray
1-d numpy array of <...>_Q(y) in NZ10 where latitude y is given by ylat; dimension = (nlat).
(3) lwa_result : numpy.ndarray
2-d numpy array of local wave activity values; dimension = (nlat, nlon).
(4) capsigma: numpy.ndarray
2-d numpy array of non-conservative force contribution value; dimension = (nlat, nlon).
"""
from hn2016_falwa import basis
nlat = vort.shape[0]
nlon = vort.shape[1]
if nlat_s is None:
nlat_s = nlat // 2
if n_points is None:
n_points = nlat_s
qref = np.zeros(nlat)
lwa_result = np.zeros((nlat, nlon))
if ncforce is not None:
capsigma = np.zeros((nlat, nlon))
if vgrad is not None:
brac_result = np.zeros(nlat)
# --- Southern Hemisphere ---
if vgrad is None:
qref1, brac = basis.eqvlat(ylat[:nlat_s], vort[:nlat_s, :],
area[:nlat_s, :],
n_points, planet_radius=planet_radius)
else:
qref1, brac = basis.eqvlat(ylat[:nlat_s], vort[:nlat_s, :],
area[:nlat_s, :],
n_points, planet_radius=planet_radius,
vgrad=vgrad[:nlat_s, :])
qref[:nlat_s] = qref1
if vgrad is not None:
brac_result[:nlat_s] = brac
if ncforce is not None:
lwa_result[:nlat_s, :], capsigma[:nlat_s, :] = \
basis.lwa(nlon, nlat_s,
vort[:nlat_s, :],
qref1, dmu[:nlat_s],
ncforce=ncforce[:nlat_s, :])
else:
lwa_result[:nlat_s, :], _ = basis.lwa(nlon, nlat_s, vort[:nlat_s, :],
qref1, dmu[:nlat_s])
# --- Northern Hemisphere ---
vort2 = -vort[::-1, :]
# Added the minus sign, but gotta see if NL_North is affected
if vgrad is None:
qref2, brac = basis.eqvlat(ylat[:nlat_s], vort2[:nlat_s, :],
area[:nlat_s, :],
n_points, planet_radius=planet_radius)
else:
vgrad2 = -vgrad[::-1, :] # Is this correct?
qref2, brac = basis.eqvlat(ylat[:nlat_s], vort2[:nlat_s, :],
area[:nlat_s, :],
n_points, planet_radius=planet_radius,
vgrad=vgrad2[:nlat_s, :])
qref[-nlat_s:] = -qref2[::-1]
if vgrad is not None:
brac_result[-nlat_s:] = -brac[::-1]
if ncforce is not None:
lwa_result[-nlat_s:, :], \
capsigma[-nlat_s:, :] = basis.lwa(nlon, nlat_s, vort[-nlat_s:, :],
qref[-nlat_s:],
dmu[-nlat_s:],
ncforce=ncforce[-nlat_s:, :])
else:
lwa_result[-nlat_s:, :], _ = basis.lwa(nlon, nlat_s, vort[-nlat_s:, :],
qref[-nlat_s:], dmu[-nlat_s:])
# Return things as dictionary
return_dict = dict()
return_dict['qref'] = qref
return_dict['lwa_result'] = lwa_result
if vgrad is not None:
return_dict['brac_result'] = brac_result
if ncforce is not None:
return_dict['capsigma'] = capsigma
return return_dict
def qgpv_eqlat_lwa(ylat, vort, area, dmu, nlat_s=None, n_points=None,
planet_radius=6.378e+6):
"""
Compute equivalent latitutde *qref* and local wave activity *lwa_result* based
on Quasi-geostrophic potential vorticity field *vort* at a pressure level as
outlined in Huang and Nakamura (2017).
Parameters
----------
ylat : numpy.array
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
vort : numpy.ndarray
2-d numpy array of Quasi-geostrophic potential vorticity field; dimension = (nlat, nlon).
area : numpy.ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
dmu: numpy.array
1-d numpy array of latitudinal differential length element (e.g. dmu = planet_radius * cos(lat) d(lat)). Size = nlat.
nlat_s : int, default None
The index of grid point that defines the extent of hemispheric domain from the pole. If input as None, it will be initialize as nlat // 2.
n_points : int, default None
Analysis resolution to calculate equivalent latitude. If input as None, it will be initialized as *nlat_s*.
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
Returns
-------
qref : numpy.ndarray
1-d numpy array of value Q(y) where latitude y is given by ylat; dimension = (nlat).
lwa_result : numpy.ndarray
2-d numpy array of local wave activity values;
dimension = [nlat_s x nlon]
"""
from hn2016_falwa import basis
nlat = vort.shape[0]
nlon = vort.shape[1]
if nlat_s is None:
nlat_s = nlat // 2
if n_points is None:
n_points = nlat_s
qref = np.zeros(nlat)
lwa_result = np.zeros((nlat, nlon))
# --- Southern Hemisphere ---
qref1, _ = basis.eqvlat(ylat[:nlat_s], vort[:nlat_s, :],
area[:nlat_s, :],
n_points, planet_radius=planet_radius)
qref[:nlat_s] = qref1
lwa_result[:nlat_s, :], _ = basis.lwa(nlon, nlat_s,
vort[:nlat_s, :],
qref1, dmu[:nlat_s])
# --- Northern Hemisphere ---
vort2 = -vort[::-1, :]
# Added the minus sign, but gotta see if NL_North is affected
qref2, _ = basis.eqvlat(ylat[:nlat_s], vort2[:nlat_s, :], area[:nlat_s, :],
n_points, planet_radius=planet_radius)
qref[-nlat_s:] = -qref2[::-1]
lwa_result[-nlat_s:, :], _ = basis.lwa(nlon, nlat_s,
vort[-nlat_s:, :],
qref[-nlat_s:],
dmu[-nlat_s:])
return qref, lwa_result
def eqvlat_bracket_hemispheric(ylat, vort, area, nlat_s=None, n_points=None,
planet_radius=6.378e+6, vgrad=None):
"""
Compute equivalent latitude and <...>_Q in Nakamura and Zhu (2010) in a hemispheric domain.
Parameters
----------
ylat : numpy.array
1-d numpy array of latitude (in degree) with equal spacing in ascending order; dimension = nlat.
vort : numpy.ndarray
2-d numpy array of vorticity values; dimension = (nlat, nlon).
area : numpy.ndarray
2-d numpy array specifying differential areal element of each grid point; dimension = (nlat, nlon).
nlat_s : int, default None
The index of grid point that defines the extent of hemispheric domain from the pole. If input as None, it will be initialize as nlat // 2.
n_points : int, default None
Analysis resolution to calculate equivalent latitude. If input as None, it will be initialized as *nlat_s*.
planet_radius : float, default 6.378e+6
radius of spherical planet of interest consistent with input 'area'.
vgrad: numpy.ndarray, optional
2-d numpy array of laplacian (or higher-order laplacian) values; dimension = (nlat, nlon)
Returns
-------
q_part : numpy.ndarray
1-d numpy array of value Q(y) where latitude y is given by ylat; dimension = (nlat).
brac : numpy.ndarray or None
1-d numpy array of averaged vgrad in the square bracket.
If *vgrad* = None, *brac* = None.
"""
from hn2016_falwa import basis
nlat = vort.shape[0]
qref = np.zeros(nlat)
brac = np.zeros(nlat)
if nlat_s is None:
nlat_s = nlat // 2
if n_points is None:
n_points = nlat_s
# --- Southern Hemisphere ---
qref1, brac1 = basis.eqvlat(ylat[:nlat_s], vort[:nlat_s, :],
area[:nlat_s, :],
n_points, planet_radius=planet_radius,
vgrad=vgrad)
qref[:nlat_s] = qref1
# --- Northern Hemisphere ---
vort2 = -vort[::-1, :]
qref2, brac2 = basis.eqvlat(ylat[:nlat_s], vort2[:nlat_s, :],
area[:nlat_s, :],
n_points, planet_radius=planet_radius,
vgrad=vgrad)
qref[-nlat_s:] = qref2[::-1]
brac[:nlat_s] = brac1
brac[-nlat_s:] = brac2[::-1]
return qref, brac
