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BUFR - Hodograph
# (C) Copyright 2017- 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.
#
import metview as mv
import numpy as np
def build_view(hodo_incr=5, hodo_max_val=35):
"""
Utility function to build a view for the hodograph
"""
# ----------------------------
# define the hodograph view
# ----------------------------
# the maximum radial size of the coordinate system
hodo_max_val = np.ceil(hodo_max_val / hodo_incr) * hodo_incr
# define horizontal and vertical axes
h_axis = mv.maxis(axis_position="left", axis_tick="off", axis_tick_label="off")
v_axis = mv.maxis(axis_position="bottom", axis_tick="off", axis_tick_label="off")
# the view
view = mv.cartesianview(
x_automatic="off",
x_min=-hodo_max_val,
x_max=hodo_max_val,
y_automatic="off",
y_min=-hodo_max_val,
y_max=hodo_max_val,
horizontal_axis=h_axis,
vertical_axis=v_axis,
subpage_frame="on",
subpage_frame_thickness=1,
subpage_x_position=5,
subpage_y_position=5,
subpage_x_length=90,
subpage_y_length=90,
)
# define the hodograph plot page.
# NOTE: In order to correctly render the hodograph (we want
# concentric circles instead of ellipses) we have to ensure
# that the physical width and height of the plot are the same.
# Please note that while the page size is defined in % the
# superpage size is defined in cm! See also subpage size in the view.
# physical size of the whole plot (A4 landscape)
sp_width = 29.7
sp_height = 21
hodo_width = 18.5 # cm
hodo_height = 18.5 # cm
page_width = 100 * hodo_width / sp_width
page_height = 100 * hodo_height / sp_height
page_top = 10
page_left = (100 - page_width) / 2
hodo_page = mv.plot_page(
top=page_top,
bottom=page_top + page_height,
left=page_left,
right=page_left + page_width,
view=view,
)
# define the superpage (A4 landscape)
dw = mv.plot_superpage(pages=[hodo_page])
return dw[0]
def build_hodo_bg(
hodo_incr=5,
hodo_max_val=35,
hodo_highlight=[10, 20, 30],
hodo_label=[10, 20, 30],
hodo_label_size=0.5,
hodo_colour="black",
):
"""
Utility function to generate plot objects making up
the hodograph background
"""
# the maximum radial size of the coordinate system
hodo_max_val = np.ceil(hodo_max_val / hodo_incr) * hodo_incr
gr_lst = []
# build the concentric circles
sp = hodo_incr
angle_incr = 2 * np.pi / 180
while sp <= hodo_max_val:
xp = [np.cos(i * angle_incr) * sp for i in range(1, 182)]
yp = [np.sin(i * angle_incr) * sp for i in range(1, 182)]
gr = mv.xy_curve(xp, yp, hodo_colour, "solid", 3 if sp in hodo_highlight else 1)
gr_lst.append(gr)
sp += hodo_incr
# build horizontal and vertical lines going
# through the centre
gr_lst.append(
mv.xy_curve([-hodo_max_val, hodo_max_val], [0, 0], hodo_colour, "solid", 1)
)
gr_lst.append(
mv.xy_curve([0, 0], [-hodo_max_val, hodo_max_val], hodo_colour, "solid", 1)
)
# add labels to the horizontal line
vis = mv.input_visualiser(
input_plot_type="xy_point",
input_x_values=[-v for v in hodo_label] + hodo_label,
input_y_values=[0] * 2 * len(hodo_label),
input_values=hodo_label + hodo_label,
)
sym = mv.msymb(
symbol_colour=hodo_colour,
symbol_text_font_size=hodo_label_size,
symbol_text_font_style="normal",
symbol_text_position="bottom",
)
gr_lst.extend([vis, sym])
return gr_lst
def build_hodo_wind(prof, pres_bins, pres_colours):
"""
Utility function to generate plot objects for the hodograph
wind data (per bin)
"""
# get individual profiles as vectors. Values are sorted by descending
# pressure, no missing values includes.
info = mv.thermo_data_values(prof, 0)
p = info["p_wind"]
u = info["u"]
v = info["v"]
gr_wind = []
for i in range(len(pres_bins) - 1):
# collect wind data in bin
u_val = []
v_val = []
for k in range(len(p)):
if (
not np.isnan(p[k])
and not np.isnan(u[k])
and not np.isnan(v[k])
and p[k] <= pres_bins[i]
and p[k] >= pres_bins[i + 1]
):
u_val.append(u[k])
v_val.append(v[k])
# build graph object
if u_val and v_val:
vis = mv.input_visualiser(input_x_values=u_val, input_y_values=v_val)
gr = mv.mgraph(
legend="on",
graph_line_colour=pres_colours[i],
graph_line_style="solid",
graph_line_thickness=5,
)
gr_wind.extend([vis, gr])
return gr_wind
# read BUFR data
filename = "temp.bufr"
if mv.exist(filename):
b = mv.read(filename)
else:
b = mv.gallery.load_dataset(filename)
# define station id
statid = "78583"
# extract thermo profile
prof = mv.thermo_bufr(data=b, station=mv.stations(search_key="ident", ident=statid))
# define the hodograph background
hodo_incr = 5
hodo_highlight = [10, 20, 30]
hodo_label = [10, 20, 30]
hodo_max_val = 35
hodo_colour = "RGB(0.4,0.4,0.4)"
# define the wind speed bins and their associated colours
pres_bins = [1050, 700, 500, 300, 200, 50]
pres_colours = ["red", "kelly_green", "sky", "blue", "magenta"]
# generate the graphical objects for the hodograph background
gr_hodo_bg = build_hodo_bg(
hodo_incr=hodo_incr,
hodo_highlight=hodo_highlight,
hodo_label=hodo_label,
hodo_max_val=hodo_max_val,
hodo_colour=hodo_colour,
)
# generate the graphical objects for wind data on the hodograph
gr_hodo_wind = build_hodo_wind(prof, pres_bins, pres_colours)
# build the view for the hodograph
view = build_view(hodo_incr=hodo_incr, hodo_max_val=hodo_max_val)
# define legend with custom labels
legend_text = []
for i in range(len(pres_bins) - 1):
legend_text.append(str(pres_bins[i]) + "-" + str(pres_bins[i + 1]))
legend = mv.mlegend(
legend_display_type="disjoint",
legend_text_font_size=0.5,
legend_text_composition="user_text_only",
legend_user_lines=legend_text,
)
# define title
info = mv.thermo_data_info(prof)
title_txt = "HODOGRAPH Date: {} {} UTC WMO id: {} Lat/Lon: {:.2f}/{:.2f}".format(
int(info["date"]), int(info["time"]), int(info["station"]), info["lat"], info["lon"]
)
title = mv.mtext(text_lines=title_txt, text_font_size=0.5, text_colour="charcoal")
# define the output plot file
mv.setoutput(mv.pdf_output(output_name="hodograph"))
# generate the plot
mv.plot(view, gr_hodo_bg, gr_hodo_wind, legend, title)