Notebook

Dfs2 - Snow Compare¶

Using This Notebook¶

Provides a simple differencing tool to compare two Dfs2 files, in this case MIKE SHE and MODIS snow cover
Due to the ipywidgets controls which dynamically query Dfs2 files, this notebook requires local execution
Modify the inputs section cell to provide file paths and then execute all cells
Use the horizontal slider controls in the Analysis section to move back and forth in time for each Dfs2. A simple grid calculation will be performed showing which cells have lower, similar, or higher values, allowing you to identify areas of concern for further investigation

Environment Setup¶

The following packages were used at the time of development, and you may be able to use more recent versions:
- ipykernel 6.29.0
- mikeio 1.6.3
- matplotlib 3.8.2
- ipywidgets 8.1.5

In [ ]:

import matplotlib as mpl
import matplotlib.pyplot as plt
import numpy as np
import mikeio
import ipywidgets as widgets

Inputs Section¶

In [ ]:

mikeSheSnowDfs2Path = "../tests/testdata/MikeSheExtract.dfs2"
modisSnowDfs2Path = "../tests/testdata/ModisExtract.dfs2"

mikeSheSnowDfs2 = mikeio.read(mikeSheSnowDfs2Path)
modisSnowDfs2 = mikeio.read(modisSnowDfs2Path)

Functions Section¶

In [ ]:

def sliders_changed(msheSlider, modisSlider):
    modisItemName = 'Snow Cover'
    msheItemName = 'Fraction of cell area covered by Snow'

    timeIndex = modisSnowDfs2[modisItemName].time.get_loc(modisSlider)
    modisSingleTimestep = modisSnowDfs2[modisItemName].isel(
        time=timeIndex) / 100.0

    timeIndex = mikeSheSnowDfs2[msheItemName].time.get_loc(msheSlider)
    mikeSheSingleTimestep = mikeSheSnowDfs2[msheItemName].isel(time=timeIndex)

    # use nans in MSHE to set nans in MODIS to mask out catchment
    modisSingleTimestep.values = np.where(np.isnan(
        mikeSheSingleTimestep.values), mikeSheSingleTimestep.values, modisSingleTimestep.values)
    modisSingleDataArray = modisSingleTimestep.to_xarray()
    modisSingleDataArray.attrs['units'] = 'Fraction'

    # 3 column layout
    fig, (ax1, ax2, ax3) = plt.subplots(1, 3, figsize=(21, 5))
    modisSingleDataArray.plot.pcolormesh(
        ax=ax1, vmin=0.0, vmax=1.0, cmap="jet")
    ax1.set_title('MODIS')

    mikeSheSingleDataArray = mikeSheSingleTimestep.to_xarray()
    mikeSheSingleDataArray.attrs['units'] = 'Fraction'
    mikeSheSingleDataArray.plot.pcolormesh(
        ax=ax2, vmin=0.0, vmax=1.0, cmap="jet")
    ax2.set_title('MIKE SHE')

    diff = modisSingleTimestep.copy()
    diff.values = modisSingleTimestep.values - mikeSheSingleTimestep.values

    categories = ['MSHE Higher', 'Similar', 'Similar', 'MODIS Higher']
    colors = ['yellow', 'green', 'red']
    boundaries = [-1.0, -0.1, 0.1, 1.0]

    cmap = mpl.colors.ListedColormap(colors)
    norm = mpl.colors.BoundaryNorm(boundaries, cmap.N)

    diffPlot = diff.to_xarray().plot.pcolormesh(ax=ax3, cmap=cmap, norm=norm)
    cbar = diffPlot.colorbar
    cbar.set_ticklabels(categories)
    cbar.set_label(None)

    ax3.set_title('Difference (MODIS - MIKE SHE)')
    plt.tight_layout()


style = {'description_width': 'initial'}

msheSlider = widgets.SelectionSlider(
    options=mikeSheSnowDfs2.time,
    value=mikeSheSnowDfs2.time[0],
    description='MSHE Timestep',
    disabled=False,
    continuous_update=False,
    orientation='horizontal',
    readout=True,
    style=style,
    layout=widgets.Layout(width='800px', margin='0 30px 0 0 ')
)

# constrain the modis timesteps to the mshe, as modis covers far more
modis_time_slicer = modisSnowDfs2.time.slice_indexer(
    start=mikeSheSnowDfs2.time[0], end=mikeSheSnowDfs2.time[-1])
filtered_modis_times = modisSnowDfs2.time[modis_time_slicer]

modisSlider = widgets.SelectionSlider(
    options=filtered_modis_times,
    value=filtered_modis_times[0],
    description='MODIS Timestep',
    disabled=False,
    continuous_update=False,
    orientation='horizontal',
    readout=True,
    style=style,
    layout=widgets.Layout(width='800px', margin='0 30px 0 0 ')
)

Analysis Section¶

In [ ]:

ui = widgets.HBox([modisSlider, msheSlider])
out = widgets.interactive_output(sliders_changed, {'msheSlider' : msheSlider, 'modisSlider' : modisSlider})
display(ui, out)