Temperature Below 0C Example

# Metview Macro

#  **************************** LICENSE START ***********************************
# 
#  Copyright 2014 ECMWF. This software is distributed under the terms
#  of the Apache License version 2.0. In applying this license, ECMWF does not
#  waive the privileges and immunities granted to it by virtue of its status as
#  an Intergovernmental Organization or submit itself to any jurisdiction.
# 
#  ***************************** LICENSE END ************************************

# ------------------------------------------------------------------
# Tags: contour
# Title: Temperature Below 0C
# Description: Demonstrates how to define a contour level list so that only
#              field values in a certain range are coloured.
# See also:
# https://software.ecmwf.int/magics/Contour+examples+contour10
# ------------------------------------------------------------------

# read the input grib file
my_data = read("2m_temperature.grib")

# set up the geographical area
my_view = geoview(map_area_definition : "CORNERS",
                  map_projection      : "CYLINDRICAL",
                  area                : [35,-15,70,35])

# set up the background coastlines
my_background = mcoast(map_label                : "ON",
                       map_grid_line_style      : "DASH",
                       map_grid_colour          : "GREY",
                       map_coastline_colour     : "BLACK",
                       map_coastline_land_shade : "OFF")

# set up the contour so that only one level is coloured
my_contour = mcont(contour_level_selection_type   : "LEVEL_LIST",
                   contour_level_list             : [-70.00,0.00],
                   contour_label                  : "OFF",
                   legend                         : "ON",
                   contour                        : "OFF",
                   contour_shade                  : "ON",
                   contour_shade_colour_method    : "LIST",
                   contour_shade_method           : "AREA_FILL",
                   contour_shade_colour_direction : "ANTI_CLOCKWISE",
                   contour_shade_colour_list      : ["rgba(0.498,0.8,0.8,0.6)"])

# set-up the land colour
my_foreground =  mcoast(map_coastline_land_shade        : "ON",
                       map_coastline_land_shade_colour : "CREAM")


# set-up the title
my_title = mtext(text_font_size     : 0.5,
                 text_lines         : ["<font size='0.7'>Temperature below 0C</font>",
                                       "<magics_title/>",
                                       ""],
                 text_colour        : "CHARCOAL")

# define the output media
to_psfile = ps_output
(
    output_name : "plot" # extension is added automatically
)

# check the runmode and decide which media to putput the plot to
mode = runmode()
if       (mode = "execute")    then setoutput(to_psfile)
else if  (mode = "batch")      then setoutput(to_psfile)
else if  (mode = "visualise")  then print('screen')
else     fail("Only execute, batch and visualise allowed")
end if

# plot the data onto the map
plot(my_view,my_background,my_data,my_contour,my_foreground,my_title)