Show dominating source

import os
from datetime import datetime
import xarray as xr
import opendrift
from opendrift.models.oceandrift import OceanDrift

of = 'test.nc'

Seed elements at 5 different locations/longitudes

lons = [4, 4.2, 4.3, 4.32, 4.6]
t = datetime.now()

o = OceanDrift(loglevel=20)
o.set_config('environment:constant:y_sea_water_velocity', .1)

for i, lon in enumerate(lons):
    o.seed_elements(lon=lon, lat=60, radius=3000, number=2000, time=t, origin_marker_name='Lon %f' % lon)
o.run(steps=15, outfile=of)
13:21:37 INFO    opendrift:513: OpenDriftSimulation initialised (version 1.14.2 / v1.14.2-79-ga5f3ce3)
13:21:37 INFO    opendrift.models.basemodel.environment:206: Adding a global landmask from GSHHG
13:21:41 INFO    opendrift.models.basemodel.environment:229: Fallback values will be used for the following variables which have no readers:
13:21:41 INFO    opendrift.models.basemodel.environment:232:    x_sea_water_velocity: 0.000000
13:21:41 INFO    opendrift.models.basemodel.environment:232:    sea_surface_height: 0.000000
13:21:41 INFO    opendrift.models.basemodel.environment:232:    x_wind: 0.000000
13:21:41 INFO    opendrift.models.basemodel.environment:232:    y_wind: 0.000000
13:21:41 INFO    opendrift.models.basemodel.environment:232:    upward_sea_water_velocity: 0.000000
13:21:41 INFO    opendrift.models.basemodel.environment:232:    ocean_vertical_diffusivity: 0.000000
13:21:41 INFO    opendrift.models.basemodel.environment:232:    sea_surface_wave_significant_height: 0.000000
13:21:41 INFO    opendrift.models.basemodel.environment:232:    sea_surface_wave_stokes_drift_x_velocity: 0.000000
13:21:41 INFO    opendrift.models.basemodel.environment:232:    sea_surface_wave_stokes_drift_y_velocity: 0.000000
13:21:41 INFO    opendrift.models.basemodel.environment:232:    ocean_mixed_layer_thickness: 50.000000
13:21:41 INFO    opendrift.models.basemodel.environment:232:    sea_floor_depth_below_sea_level: 10000.000000
13:21:41 INFO    opendrift:1722: Skipping environment variable ocean_vertical_diffusivity because of condition ['drift:vertical_mixing', 'is', False]
13:21:41 INFO    opendrift:1722: Skipping environment variable ocean_mixed_layer_thickness because of condition ['drift:vertical_mixing', 'is', False]
13:21:41 INFO    opendrift:889: Using existing reader for land_binary_mask
13:21:41 INFO    opendrift:918: All points are in ocean
13:21:41 INFO    opendrift:1948: Storing previous position of elements for coastline interaction
13:21:41 INFO    opendrift:2009: 2025-07-01 13:21:37.371474 - step 1 of 15 - 10000 active elements (0 deactivated)
13:21:41 INFO    opendrift:2009: 2025-07-01 14:21:37.371474 - step 2 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-01 15:21:37.371474 - step 3 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-01 16:21:37.371474 - step 4 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-01 17:21:37.371474 - step 5 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-01 18:21:37.371474 - step 6 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-01 19:21:37.371474 - step 7 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-01 20:21:37.371474 - step 8 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-01 21:21:37.371474 - step 9 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-01 22:21:37.371474 - step 10 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-01 23:21:37.371474 - step 11 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-02 00:21:37.371474 - step 12 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-02 01:21:37.371474 - step 13 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-02 02:21:37.371474 - step 14 of 15 - 10000 active elements (0 deactivated)
13:21:42 INFO    opendrift:2009: 2025-07-02 03:21:37.371474 - step 15 of 15 - 10000 active elements (0 deactivated)
<xarray.Dataset> Size: 15MB
Dimensions:                                   (trajectory: 10000, time: 16)
Coordinates:
  * trajectory                                (trajectory) int32 40kB 0 ... 9999
  * time                                      (time) datetime64[ns] 128B 2025...
Data variables: (12/21)
    status                                    (trajectory, time) float64 1MB ...
    moving                                    (trajectory, time) float64 1MB ...
    age_seconds                               (trajectory, time) float32 640kB ...
    origin_marker                             (trajectory, time) float64 1MB ...
    lon                                       (trajectory, time) float32 640kB ...
    lat                                       (trajectory, time) float32 640kB ...
    ...                                        ...
    upward_sea_water_velocity                 (trajectory, time) float32 640kB ...
    sea_surface_wave_significant_height       (trajectory, time) float32 640kB ...
    sea_surface_wave_stokes_drift_x_velocity  (trajectory, time) float32 640kB ...
    sea_surface_wave_stokes_drift_y_velocity  (trajectory, time) float32 640kB ...
    sea_floor_depth_below_sea_level           (trajectory, time) float32 640kB ...
    land_binary_mask                          (trajectory, time) float32 640kB ...
Attributes: (12/117)
    Conventions:                                                           CF...
    standard_name_vocabulary:                                              CF...
    featureType:                                                           tr...
    title:                                                                 Op...
    summary:                                                               Ou...
    keywords:                                                              tr...
    ...                                                                    ...
    geospatial_lon_units:                                                  de...
    geospatial_lon_resolution:                                             point
    runtime:                                                               0:...
    geospatial_vertical_min:                                               0.0
    geospatial_vertical_max:                                               0.0
    geospatial_vertical_positive:                                          up


Calculate spatial density of elements at 1500m grid spacing

d = o.get_histogram(pixelsize_m=1500, weights=None)
dom = d.argmax(dim='origin_marker', skipna=True)
dom = dom.where(d.sum(dim='origin_marker')>0)
dom.name = 'Dominating source'
13:21:43 INFO    opendrift:3807:        calculating for origin_marker 0...
13:21:43 INFO    opendrift:3807:        calculating for origin_marker 1...
13:21:43 INFO    opendrift:3807:        calculating for origin_marker 2...
13:21:43 INFO    opendrift:3807:        calculating for origin_marker 3...
13:21:43 INFO    opendrift:3807:        calculating for origin_marker 4...

Show which of the 5 sources are dominating within each grid cell

o.animation(background=dom, show_elements=False, bgalpha=1,
             legend=list(o.origin_marker.values()), colorbar=False, vmin=0, vmax=4)
/opt/conda/envs/opendrift/lib/python3.13/site-packages/cartopy/mpl/geoaxes.py:1692: UserWarning: No data for colormapping provided via 'c'. Parameters 'vmin', 'vmax' will be ignored
  result = super().scatter(*args, **kwargs)
13:21:54 INFO    opendrift:4527: Saving animation to /root/project/docs/source/gallery/animations/example_dominating_0.gif...
13:22:04 INFO    opendrift:2968: Time to make animation: 0:00:20.494579
../_images/example_dominating_0.gif
os.remove(of)

Total running time of the script: (0 minutes 33.383 seconds)

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