Geographical box diagnostics

Geographical box diagnostics are added using the add_geobox_stat() method.

Requested statistics will be computed for the provided field in each box defined by the res_lon and res_lat parameters.

Add a geographical box diagnostics computing requested statistics
for the provided field in each box defined by the res_lon and res_lat
parameters.

Geobox stat data and plots can be accessed or created using special keywords:

 * plot="box" (default): color mesh representation, on an x-axis/y-axis grid.
 * plot="3d": 3d color mesh representation, on an x-axis/y-axis/z-axis 3d grid.

Parameters
----------
name
    Name of the diagnostic.
field
    Field on which to compute.
stats
    List of statistics to compute (count, max, mean, median, min, std, var,
    mad).
res_lon
    Minimum, maximum and box size over the longitude (Default: -180, 180, 4).
res_lat
    Minimum, maximum and box size over the latitude (Default: -90, 90, 4).
projection
    Projection in which to project longitude and latitude values before binning
    data.
box_selection
    Field used as selection for computation of the ``count`` statistic.
    Box in which the box_selection field does not contain any data will be set
    to NaN instead of 0.
stat_selection
    Selection clip used to invalidate (set to NaN) some bins.
    Valid conditions are:

        * count
        * min
        * max
        * mean
        * median
        * std
        * var
        * mad

    These clips are Python vector clips.
    Examples:

        * count :>= 10 && max :< 100
        * min :> 3
        * median :> 10 && mean :> 9

This kind of diagnostic is plotted as as pseudo-color map plots with a non-regular rectangular grid.

Diagnostic setting

In the following example we are setting a box diagnostic computing 3 statistics (mean, standard deviation and variance) at a daily frequency for a user defined SLA field.

Box are defined as 2° longitude x 2° latitude over the entire surface of the globe.

from casys import Field

sla = Field(
    name="SLA",
    source="ORBIT.ALTI - RANGE.ALTI - MEAN_SEA_SURFACE.MODEL.CNESCLS15",
    unit="m",
)

ad.add_geobox_stat(
    name="SLA box stat",
    field=sla,
    stats=["count", "median", "std"],
    res_lon=(-180, 180, 2),
    res_lat=(-90, 90, 2),
)

ad.compute()

Diagnostic plotting

Standard 2D plot

Geographical box diagnostics can be plotted as pseudo-color map plots with a non-regular rectangular grid by using the default plot parameter value box.

CasysPlot requires a stat parameter to be given in order to know which statistic to display.

from casys import CasysPlot, PlotParams

plot = CasysPlot(
    data=ad,
    data_name="SLA box stat",
    stat="std",
    plot_params=PlotParams(color_limits=(0, 1)),
    plot="box",
)

plot.show()

3D plot

Geographical box diagnostics can be plotted as 3d surface plots with a non-regular rectangular grid, with the *plot parameter value 3D.

CasysPlot requires a stat parameter to be given in order to know which statistic to display.

plot = CasysPlot(
    data=ad,
    data_name="SLA box stat",
    stat="std",
    plot_params=PlotParams(color_limits=(0, 1)),
    plot="3d",
)

plot.show()