def test_dist_approx_pass(self):
"""Test against matlab reference."""
lats1 = 45.5
lons1 = -32.2
cos_lats1 = np.cos(np.radians(lats1))
lats2 = 14
lons2 = 56
self.assertAlmostEqual(
7709.827814738594,
interp.dist_approx(lats1, lons1, cos_lats1, lats2, lons2))
def _wind_per_node(coastal_centr, track, v_trans, model):
""" Compute sustained winds at each centroid.
Parameters:
coastal_centr (2d np.array): centroids
track (xr.Dataset): track latitudes
v_trans (np.array): track translational velocity
model (int): Holland model selection according to MODEL_VANG
Returns:
2d np.array
"""
t_lat, t_lon = track.lat.values, track.lon.values
t_rad, t_env = track.radius_max_wind.values, track.environmental_pressure.values
t_cen, t_tstep = track.central_pressure.values, track.time_step.values
centr_cos_lat = np.cos(np.radians(coastal_centr[:, 0]))
intensity = np.zeros((coastal_centr.shape[0], ))
n_nodes = t_lat.size
if 'n_nodes' in track.attrs:
n_nodes = track.attrs['n_nodes']
for i_node in range(1, n_nodes):
# compute distance to all centroids
r_arr = dist_approx(coastal_centr[:, 0], coastal_centr[:, 1], \
centr_cos_lat, t_lat[i_node], t_lon[i_node])
# Choose centroids that are close enough
close_centr = np.argwhere(r_arr < CENTR_NODE_MAX_DIST_KM).reshape(-1, )
r_arr = r_arr[close_centr]
# translational component
if i_node < t_lat.size - 1:
v_trans_corr = _vtrans_correct(t_lat[i_node:i_node+2], \
t_lon[i_node:i_node+2], t_rad[i_node], \
coastal_centr[close_centr, :], r_arr)
else:
v_trans_corr = np.zeros((r_arr.size, ))
# angular component
v_ang = _vang_sym(t_env[i_node], t_cen[i_node - 1:i_node + 1],
t_lat[i_node], t_tstep[i_node], t_rad[i_node], r_arr,
v_trans[i_node - 1], model)
v_full = v_trans[i_node - 1] * v_trans_corr + v_ang
v_full[np.isnan(v_full)] = 0
v_full[v_full < TropCyclone.intensity_thres] = 0
# keep maximum instantaneous wind
intensity[close_centr] = np.maximum(intensity[close_centr], v_full)
return intensity
def _vtrans(t_lat, t_lon, t_tstep, ureg):
""" Translational spped at every track node.
Parameters:
t_lat (np.array): track latitudes
t_lon (np.array): track longitudes
t_tstep (np.array): track time steps
ureg (UnitRegistry): units handler
Returns:
np.array
"""
v_trans = dist_approx(t_lat[:-1], t_lon[:-1], np.cos(np.radians(
t_lat[:-1])), t_lat[1:], t_lon[1:]) / t_tstep[1:]
v_trans = (v_trans * ureg.km / ureg.hour).to(ureg.meter /
ureg.second).magnitude
# nautical miles/hour, limit to 30 nmph
v_max = (30 * ureg.knot).to(ureg.meter / ureg.second).magnitude
v_trans[v_trans > v_max] = v_max
return v_trans
