Note
Click here to download the full example code
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)
Out:
13:51:12 INFO opendrift.models.basemodel: OpenDriftSimulation initialised (version 1.7.1 / v1.7.1-87-g074c1d2)
13:51:12 INFO opendrift.readers.reader_netCDF_CF_generic: Opening dataset: /root/project/tests/test_data/16Nov2015_NorKyst_z_surface/norkyst800_subset_16Nov2015.nc
13:51:13 INFO opendrift.models.basemodel: Fallback values will be used for the following variables which have no readers:
13:51:13 INFO opendrift.models.basemodel: x_wind: 0.000000
13:51:13 INFO opendrift.models.basemodel: y_wind: 0.000000
13:51:13 INFO opendrift.models.basemodel: upward_sea_water_velocity: 0.000000
13:51:13 INFO opendrift.models.basemodel: ocean_vertical_diffusivity: 0.000000
13:51:13 INFO opendrift.models.basemodel: sea_surface_wave_significant_height: 0.000000
13:51:13 INFO opendrift.models.basemodel: sea_surface_wave_stokes_drift_x_velocity: 0.000000
13:51:13 INFO opendrift.models.basemodel: sea_surface_wave_stokes_drift_y_velocity: 0.000000
13:51:13 INFO opendrift.models.basemodel: sea_surface_wave_period_at_variance_spectral_density_maximum: 0.000000
13:51:13 INFO opendrift.models.basemodel: sea_surface_wave_mean_period_from_variance_spectral_density_second_frequency_moment: 0.000000
13:51:13 INFO opendrift.models.basemodel: surface_downward_x_stress: 0.000000
13:51:13 INFO opendrift.models.basemodel: surface_downward_y_stress: 0.000000
13:51:13 INFO opendrift.models.basemodel: turbulent_kinetic_energy: 0.000000
13:51:13 INFO opendrift.models.basemodel: turbulent_generic_length_scale: 0.000000
13:51:13 INFO opendrift.models.basemodel: sea_floor_depth_below_sea_level: 10000.000000
13:51:13 INFO opendrift.models.basemodel: Adding a dynamical landmask with max. priority based on assumed maximum speed of 1 m/s. Adding a customised landmask may be faster...
13:51:15 INFO opendrift.models.basemodel: Using existing reader for land_binary_mask
13:51:15 INFO opendrift.models.basemodel: All points are in ocean
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 00:00:00 - step 1 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 01:00:00 - step 2 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 02:00:00 - step 3 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 03:00:00 - step 4 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 04:00:00 - step 5 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 05:00:00 - step 6 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 06:00:00 - step 7 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 07:00:00 - step 8 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 08:00:00 - step 9 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 09:00:00 - step 10 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 10:00:00 - step 11 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 11:00:00 - step 12 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 12:00:00 - step 13 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 13:00:00 - step 14 of 20 - 1000 active elements (0 deactivated)
13:51:15 INFO opendrift.models.basemodel: 2015-11-16 14:00:00 - step 15 of 20 - 1000 active elements (0 deactivated)
13:51:16 INFO opendrift.models.basemodel: 2015-11-16 15:00:00 - step 16 of 20 - 1000 active elements (0 deactivated)
13:51:16 INFO opendrift.models.basemodel: 2015-11-16 16:00:00 - step 17 of 20 - 1000 active elements (0 deactivated)
13:51:16 INFO opendrift.models.basemodel: 2015-11-16 17:00:00 - step 18 of 20 - 1000 active elements (0 deactivated)
13:51:16 INFO opendrift.models.basemodel: 2015-11-16 18:00:00 - step 19 of 20 - 1000 active elements (0 deactivated)
13:51:16 INFO opendrift.models.basemodel: 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)
Out:
13:51:16 INFO opendrift.models.basemodel: OpenDriftSimulation initialised (version 1.7.1 / v1.7.1-87-g074c1d2)
13:51:16 INFO opendrift.models.basemodel: Fallback values will be used for the following variables which have no readers:
13:51:16 INFO opendrift.models.basemodel: x_wind: 0.000000
13:51:16 INFO opendrift.models.basemodel: y_wind: 0.000000
13:51:16 INFO opendrift.models.basemodel: upward_sea_water_velocity: 0.000000
13:51:16 INFO opendrift.models.basemodel: ocean_vertical_diffusivity: 0.000000
13:51:16 INFO opendrift.models.basemodel: sea_surface_wave_significant_height: 0.000000
13:51:16 INFO opendrift.models.basemodel: sea_surface_wave_stokes_drift_x_velocity: 0.000000
13:51:16 INFO opendrift.models.basemodel: sea_surface_wave_stokes_drift_y_velocity: 0.000000
13:51:16 INFO opendrift.models.basemodel: sea_surface_wave_period_at_variance_spectral_density_maximum: 0.000000
13:51:16 INFO opendrift.models.basemodel: sea_surface_wave_mean_period_from_variance_spectral_density_second_frequency_moment: 0.000000
13:51:16 INFO opendrift.models.basemodel: surface_downward_x_stress: 0.000000
13:51:16 INFO opendrift.models.basemodel: surface_downward_y_stress: 0.000000
13:51:16 INFO opendrift.models.basemodel: turbulent_kinetic_energy: 0.000000
13:51:16 INFO opendrift.models.basemodel: turbulent_generic_length_scale: 0.000000
13:51:16 INFO opendrift.models.basemodel: sea_floor_depth_below_sea_level: 10000.000000
13:51:16 INFO opendrift.models.basemodel: Adding a dynamical landmask with max. priority based on assumed maximum speed of 1 m/s. Adding a customised landmask may be faster...
13:51:18 INFO opendrift.models.basemodel: Using existing reader for land_binary_mask
13:51:18 INFO opendrift.models.basemodel: All points are in ocean
13:51:18 INFO opendrift.models.basemodel: 2015-11-16 00:00:00 - step 1 of 20 - 1000 active elements (0 deactivated)
13:51:18 WARNING opendrift.readers.basereader.structured: Data block from /root/project/tests/test_data/16Nov2015_NorKyst_z_surface/norkyst800_subset_16Nov2015.nc not large enough to cover element positions within timestep. Buffer size (7) must be increased. See `Variables.set_buffer_size`.
13:51:18 INFO opendrift.models.basemodel: 2015-11-16 01:00:00 - step 2 of 20 - 1000 active elements (0 deactivated)
13:51:18 INFO opendrift.models.basemodel: 2015-11-16 02:00:00 - step 3 of 20 - 1000 active elements (0 deactivated)
13:51:18 INFO opendrift.models.basemodel: 2015-11-16 03:00:00 - step 4 of 20 - 1000 active elements (0 deactivated)
13:51:18 INFO opendrift.models.basemodel: 2015-11-16 04:00:00 - step 5 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 05:00:00 - step 6 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 06:00:00 - step 7 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 07:00:00 - step 8 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 08:00:00 - step 9 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 09:00:00 - step 10 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 10:00:00 - step 11 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 11:00:00 - step 12 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 12:00:00 - step 13 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 13:00:00 - step 14 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 14:00:00 - step 15 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 15:00:00 - step 16 of 20 - 1000 active elements (0 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 16:00:00 - step 17 of 20 - 999 active elements (1 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 17:00:00 - step 18 of 20 - 999 active elements (1 deactivated)
13:51:19 INFO opendrift.models.basemodel: 2015-11-16 18:00:00 - step 19 of 20 - 999 active elements (1 deactivated)
13:51:19 INFO opendrift.models.basemodel: 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()
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'])
Out:
===========================
--------------------
Reader performance:
--------------------
/root/project/tests/test_data/16Nov2015_NorKyst_z_surface/norkyst800_subset_16Nov2015.nc
0:00:00.7 total
0:00:00.0 preparing
0:00:00.2 reading
0:00:00.0 interpolation
0:00:00.0 interpolation_time
0:00:00.5 rotating vectors
0:00:00.0 masking
--------------------
global_landmask
0:00:00.1 total
0:00:00.0 preparing
0:00:00.1 reading
0:00:00.0 masking
--------------------
Performance:
3.5 total time
0.3 configuration
2.4 preparing main loop
2.4 making dynamical landmask
0.0 moving elements to ocean
0.6 readers
0.1 global_landmask
0.0 postprocessing
0.7 main loop
0.3 /root/project/tests/test_data/16Nov2015_NorKyst_z_surface/norkyst800_subset_16Nov2015.nc
0.0 updating elements
0.0 cleaning up
--------------------
===========================
Model: OceanDrift (OpenDrift version 1.7.1)
1000 active Lagrangian3DArray particles (0 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_vertical_diffusivity
sea_floor_depth_below_sea_level
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
surface_downward_x_stress
surface_downward_y_stress
turbulent_generic_length_scale
turbulent_kinetic_energy
upward_sea_water_velocity
x_wind
y_wind
Time:
Start: 2015-11-16 00:00:00
Present: 2015-11-16 20:00:00
Calculation steps: 20 * 1:00:00 - total time: 20:00:00
Output steps: 21 * 1:00:00
===========================
13:51:19 WARNING opendrift.models.basemodel: Plotting fast. This will make your plots less accurate.
13:51:27 INFO opendrift.models.basemodel: Saving animation to /root/project/docs/source/gallery/animations/example_convolve_input_0.gif...
13:51:27 INFO opendrift.models.basemodel: Making animated gif...
MovieWriter imagemagick unavailable; using Pillow instead.
13:51:28 INFO opendrift.models.basemodel: Could not save animation:
13:51:28 INFO opendrift.models.basemodel: list index out of range
o.plot(fast=True)
Out:
13:51:28 WARNING opendrift.models.basemodel: Plotting fast. This will make your plots less accurate.
(<GeoAxesSubplot:title={'center':'OpenDrift - OceanDrift\n2015-11-16 00:00 to 2015-11-16 20:00 UTC (21 steps)'}>, <module 'matplotlib.pyplot' from '/opt/conda/envs/opendrift/lib/python3.9/site-packages/matplotlib/pyplot.py'>)
Total running time of the script: ( 0 minutes 18.809 seconds)