Convolve input

Decreasing the spatial resolution of fields from a reader by convolution. This may improve accuracy, see: https://doi.org/10.1016/j.rse.2019.01.001

from datetime import datetime, timedelta
import matplotlib.pyplot as plt
from opendrift.readers import reader_netCDF_CF_generic
from opendrift.models.oceandrift import OceanDrift


lon = 4.9; lat = 60.0
o = OceanDrift(loglevel=20)

reader_norkyst = reader_netCDF_CF_generic.Reader(o.test_data_folder() + '16Nov2015_NorKyst_z_surface/norkyst800_subset_16Nov2015.nc')
time = reader_norkyst.start_time

o.add_reader([reader_norkyst])
o.seed_elements(lon, lat, radius=1000, number=1000, time=time)
o.run(steps=20)
14:14:07 INFO    opendrift.models.basemodel:507: OpenDriftSimulation initialised (version 1.11.2 / v1.11.2-69-gb16198b)
14:14:07 INFO    opendrift.readers.reader_netCDF_CF_generic:102: Opening dataset: /root/project/tests/test_data/16Nov2015_NorKyst_z_surface/norkyst800_subset_16Nov2015.nc
14:14:07 INFO    opendrift.readers.reader_netCDF_CF_generic:314: Detected dimensions: {'x': 'X', 'y': 'Y', 'z': 'depth', 'time': 'time'}
14:14:07 INFO    opendrift.models.basemodel.environment:218: Adding a dynamical landmask with max. priority based on assumed maximum speed of 2.0 m/s. Adding a customised landmask may be faster...
14:14:13 INFO    opendrift.models.basemodel.environment:245: Fallback values will be used for the following variables which have no readers:
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_height: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    x_wind: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    y_wind: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    upward_sea_water_velocity: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    ocean_vertical_diffusivity: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wave_significant_height: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wave_stokes_drift_x_velocity: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wave_stokes_drift_y_velocity: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wave_period_at_variance_spectral_density_maximum: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wave_mean_period_from_variance_spectral_density_second_frequency_moment: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_swell_wave_to_direction: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_swell_wave_peak_period_from_variance_spectral_density: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_swell_wave_significant_height: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wind_wave_to_direction: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wind_wave_mean_period: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wind_wave_significant_height: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    surface_downward_x_stress: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    surface_downward_y_stress: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    turbulent_kinetic_energy: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    turbulent_generic_length_scale: 0.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    ocean_mixed_layer_thickness: 50.000000
14:14:13 INFO    opendrift.models.basemodel.environment:248:    sea_floor_depth_below_sea_level: 10000.000000
14:14:13 INFO    opendrift.models.basemodel:885: Using existing reader for land_binary_mask
14:14:13 INFO    opendrift.models.basemodel:896: All points are in ocean
14:14:13 INFO    opendrift.models.basemodel:1985: 2015-11-16 00:00:00 - step 1 of 20 - 1000 active elements (0 deactivated)
14:14:13 INFO    opendrift.models.basemodel:1985: 2015-11-16 01:00:00 - step 2 of 20 - 1000 active elements (0 deactivated)
14:14:13 INFO    opendrift.models.basemodel:1985: 2015-11-16 02:00:00 - step 3 of 20 - 1000 active elements (0 deactivated)
14:14:13 INFO    opendrift.models.basemodel:1985: 2015-11-16 03:00:00 - step 4 of 20 - 1000 active elements (0 deactivated)
14:14:13 INFO    opendrift.models.basemodel:1985: 2015-11-16 04:00:00 - step 5 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 05:00:00 - step 6 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 06:00:00 - step 7 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 07:00:00 - step 8 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 08:00:00 - step 9 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 09:00:00 - step 10 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 10:00:00 - step 11 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 11:00:00 - step 12 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 12:00:00 - step 13 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 13:00:00 - step 14 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 14:00:00 - step 15 of 20 - 1000 active elements (0 deactivated)
/root/project/opendrift/readers/interpolation/interpolators.py:17: RuntimeWarning: overflow encountered in cast
  data[mask] = np.finfo(np.float64).min
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 15:00:00 - step 16 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 16:00:00 - step 17 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 17:00:00 - step 18 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 18:00:00 - step 19 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 19:00:00 - step 20 of 20 - 1000 active elements (0 deactivated)

Store final field of x-component of current

original_current = reader_norkyst.var_block_after[list(reader_norkyst.var_block_after.keys())[0]].data_dict['x_sea_water_velocity'].copy()

For the second run, the NorKyst currents are convolved with a kernel, effectively lowering the spatial resolution. <reader>.set_convolution_kernel may also be given as an array (kernel) directly

N = 10  # Convolusion kernel size
reader_norkyst.set_convolution_kernel(N)  # Using convolution kernel for second run
o2 = OceanDrift(loglevel=20)
o2.add_reader([reader_norkyst])
o2.seed_elements(lon, lat, radius=1000, number=1000, time=time)
o2.run(steps=20)
14:14:14 INFO    opendrift.models.basemodel:507: OpenDriftSimulation initialised (version 1.11.2 / v1.11.2-69-gb16198b)
14:14:14 INFO    opendrift.models.basemodel.environment:218: Adding a dynamical landmask with max. priority based on assumed maximum speed of 2.0 m/s. Adding a customised landmask may be faster...
14:14:14 INFO    opendrift.models.basemodel.environment:245: Fallback values will be used for the following variables which have no readers:
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_height: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    x_wind: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    y_wind: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    upward_sea_water_velocity: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    ocean_vertical_diffusivity: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wave_significant_height: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wave_stokes_drift_x_velocity: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wave_stokes_drift_y_velocity: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wave_period_at_variance_spectral_density_maximum: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wave_mean_period_from_variance_spectral_density_second_frequency_moment: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_swell_wave_to_direction: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_swell_wave_peak_period_from_variance_spectral_density: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_swell_wave_significant_height: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wind_wave_to_direction: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wind_wave_mean_period: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_surface_wind_wave_significant_height: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    surface_downward_x_stress: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    surface_downward_y_stress: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    turbulent_kinetic_energy: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    turbulent_generic_length_scale: 0.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    ocean_mixed_layer_thickness: 50.000000
14:14:14 INFO    opendrift.models.basemodel.environment:248:    sea_floor_depth_below_sea_level: 10000.000000
14:14:14 INFO    opendrift.models.basemodel:885: Using existing reader for land_binary_mask
14:14:14 INFO    opendrift.models.basemodel:896: All points are in ocean
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 00:00:00 - step 1 of 20 - 1000 active elements (0 deactivated)
/root/project/opendrift/readers/interpolation/interpolators.py:17: RuntimeWarning: overflow encountered in cast
  data[mask] = np.finfo(np.float64).min
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 01:00:00 - step 2 of 20 - 1000 active elements (0 deactivated)
14:14:14 INFO    opendrift.models.basemodel:1985: 2015-11-16 02:00:00 - step 3 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 03:00:00 - step 4 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 04:00:00 - step 5 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 05:00:00 - step 6 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 06:00:00 - step 7 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 07:00:00 - step 8 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 08:00:00 - step 9 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 09:00:00 - step 10 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 10:00:00 - step 11 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 11:00:00 - step 12 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 12:00:00 - step 13 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 13:00:00 - step 14 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 14:00:00 - step 15 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 15:00:00 - step 16 of 20 - 1000 active elements (0 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 16:00:00 - step 17 of 20 - 999 active elements (1 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 17:00:00 - step 18 of 20 - 999 active elements (1 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 18:00:00 - step 19 of 20 - 999 active elements (1 deactivated)
14:14:15 INFO    opendrift.models.basemodel:1985: 2015-11-16 19:00:00 - step 20 of 20 - 999 active elements (1 deactivated)

Store final field of x-component of (convolved) current

convolved_current = reader_norkyst.var_block_after[
    "['x_sea_water_velocity', 'y_sea_water_velocity']"].data_dict['x_sea_water_velocity']

plt.subplot(2,1,1)
plt.imshow(original_current, interpolation='nearest')
plt.title('Original current field (x-component)')
clim = plt.gci().get_clim()
plt.colorbar()
plt.subplot(2,1,2)
plt.imshow(convolved_current, interpolation='nearest')
plt.clim(clim)  # Make sure plots are comparable
plt.colorbar()
plt.title('Final, convolved current field (x-component)')
plt.show()
Original current field (x-component), Final, convolved current field (x-component)

Print and plot results, with convolved currents as background

print(o)
o.animation(compare=o2, fast=True, legend=[
    'Original currents', 'Current convoled with kernel of size %s' % N],
    background=['x_sea_water_velocity', 'y_sea_water_velocity'])
===========================
--------------------
Reader performance:
--------------------
/root/project/tests/test_data/16Nov2015_NorKyst_z_surface/norkyst800_subset_16Nov2015.nc
 0:00:00.6  total
 0:00:00.0  preparing
 0:00:00.2  reading
 0:00:00.0  interpolation
 0:00:00.0  interpolation_time
 0:00:00.3  rotating vectors
 0:00:00.0  masking
--------------------
global_landmask
 0:00:00.0  total
 0:00:00.0  preparing
 0:00:00.0  reading
 0:00:00.0  masking
--------------------
Performance:
    7.8 total time
    6.9 configuration
    0.0 preparing main loop
      0.0 moving elements to ocean
    0.8 main loop
      0.0 updating elements
    0.0 cleaning up
--------------------
===========================
Model:  OceanDrift     (OpenDrift version 1.11.2)
        938 active Lagrangian3DArray particles  (62 deactivated, 0 scheduled)
-------------------
Environment variables:
  -----
  x_sea_water_velocity
  y_sea_water_velocity
     1) /root/project/tests/test_data/16Nov2015_NorKyst_z_surface/norkyst800_subset_16Nov2015.nc
  -----
  land_binary_mask
     1) global_landmask
  -----
Readers not added for the following variables:
  ocean_mixed_layer_thickness
  ocean_vertical_diffusivity
  sea_floor_depth_below_sea_level
  sea_surface_height
  sea_surface_swell_wave_peak_period_from_variance_spectral_density
  sea_surface_swell_wave_significant_height
  sea_surface_swell_wave_to_direction
  sea_surface_wave_mean_period_from_variance_spectral_density_second_frequency_moment
  sea_surface_wave_period_at_variance_spectral_density_maximum
  sea_surface_wave_significant_height
  sea_surface_wave_stokes_drift_x_velocity
  sea_surface_wave_stokes_drift_y_velocity
  sea_surface_wind_wave_mean_period
  sea_surface_wind_wave_significant_height
  sea_surface_wind_wave_to_direction
  surface_downward_x_stress
  surface_downward_y_stress
  turbulent_generic_length_scale
  turbulent_kinetic_energy
  upward_sea_water_velocity
  x_wind
  y_wind

Discarded readers:

Time:
        Start: 2015-11-16 00:00:00 UTC
        Present: 2015-11-16 20:00:00 UTC
        Calculation steps: 20 * 1:00:00 - total time: 20:00:00
        Output steps: 21 * 1:00:00
===========================

14:14:15 WARNING opendrift.models.basemodel:2356: Plotting fast. This will make your plots less accurate.
/opt/conda/envs/opendrift/lib/python3.11/site-packages/cartopy/mpl/geoaxes.py:1683: UserWarning: No data for colormapping provided via 'c'. Parameters 'cmap' will be ignored
  result = super().scatter(*args, **kwargs)
14:14:33 INFO    opendrift.models.basemodel:4547: Saving animation to /root/project/docs/source/gallery/animations/example_convolve_input_0.gif...
14:15:03 INFO    opendrift.models.basemodel:2980: Time to make animation: 0:00:47.421221
../_images/example_convolve_input_0.gif
o.plot(fast=True)
OpenDrift - OceanDrift 2015-11-16 00:00 to 2015-11-16 20:00 UTC (21 steps)
14:15:03 WARNING opendrift.models.basemodel:2356: Plotting fast. This will make your plots less accurate.

(<GeoAxes: title={'center': 'OpenDrift - OceanDrift\n2015-11-16 00:00 to 2015-11-16 20:00 UTC (21 steps)'}>, <Figure size 705.674x1100 with 1 Axes>)

Total running time of the script: (1 minutes 1.798 seconds)

Gallery generated by Sphinx-Gallery