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)

11:35:43 INFO    opendrift:576: OpenDriftSimulation initialised (version 1.14.6 / v1.14.6-7-g47225a3)
11:35:43 INFO    opendrift.models.basemodel.environment:203: Adding a global landmask from GSHHG
11:35:47 INFO    opendrift.models.basemodel.environment:227: Fallback values will be used for the following variables which have no readers:
11:35:47 INFO    opendrift.models.basemodel.environment:230:    x_sea_water_velocity: 0.000000
11:35:47 INFO    opendrift.models.basemodel.environment:230:    sea_surface_height: 0.000000
11:35:47 INFO    opendrift.models.basemodel.environment:230:    x_wind: 0.000000
11:35:47 INFO    opendrift.models.basemodel.environment:230:    y_wind: 0.000000
11:35:47 INFO    opendrift.models.basemodel.environment:230:    upward_sea_water_velocity: 0.000000
11:35:47 INFO    opendrift.models.basemodel.environment:230:    ocean_vertical_diffusivity: 0.000000
11:35:47 INFO    opendrift.models.basemodel.environment:230:    sea_surface_wave_significant_height: 0.000000
11:35:47 INFO    opendrift.models.basemodel.environment:230:    sea_surface_wave_stokes_drift_x_velocity: 0.000000
11:35:47 INFO    opendrift.models.basemodel.environment:230:    sea_surface_wave_stokes_drift_y_velocity: 0.000000
11:35:47 INFO    opendrift.models.basemodel.environment:230:    ocean_mixed_layer_thickness: 50.000000
11:35:47 INFO    opendrift.models.basemodel.environment:230:    sea_floor_depth_below_sea_level: 10000.000000
11:35:47 INFO    opendrift:1794: Skipping environment variable ocean_vertical_diffusivity because of condition ['drift:vertical_mixing', 'is', False]
11:35:47 INFO    opendrift:1794: Skipping environment variable ocean_mixed_layer_thickness because of condition ['drift:vertical_mixing', 'is', False]
11:35:47 INFO    opendrift:1805: Storing previous values of element property lon because of condition (('general:coastline_action', 'in', ['stranding', 'previous']), 'or', ('general:seafloor_action', 'in', ['previous']))
11:35:47 INFO    opendrift:1805: Storing previous values of element property lat because of condition (('general:coastline_action', 'in', ['stranding', 'previous']), 'or', ('general:seafloor_action', 'in', ['previous']))
11:35:47 INFO    opendrift:1813: Storing previous values of environment variable sea_surface_height because of condition ['drift:vertical_advection', 'is', True]
11:35:47 INFO    opendrift:952: Using existing reader for land_binary_mask to move elements to ocean
11:35:47 INFO    opendrift:982: All points are in ocean
11:35:47 INFO    opendrift:2101: 2025-11-06 11:35:43.427000 - step 1 of 15 - 10000 active elements (0 deactivated)
11:35:47 INFO    opendrift:2101: 2025-11-06 12:35:43.427000 - step 2 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 13:35:43.427000 - step 3 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 14:35:43.427000 - step 4 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 15:35:43.427000 - step 5 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 16:35:43.427000 - step 6 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 17:35:43.427000 - step 7 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 18:35:43.427000 - step 8 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 19:35:43.427000 - step 9 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 20:35:43.427000 - step 10 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 21:35:43.427000 - step 11 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 22:35:43.427000 - step 12 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-06 23:35:43.427000 - step 13 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-07 00:35:43.427000 - step 14 of 15 - 10000 active elements (0 deactivated)
11:35:48 INFO    opendrift:2101: 2025-11-07 01:35:43.427000 - 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: (12/119)
    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

xarray.Dataset

• Dimensions:
  • trajectory: 10000
  • time: 16
• Coordinates: (2)
  • trajectory
    (trajectory)
    int32
    0 1 2 3 4 ... 9996 9997 9998 9999

    cf_role :

    trajectory_id

    array([   0,    1,    2, ..., 9997, 9998, 9999], shape=(10000,), dtype=int32)

  • time
    (time)
    datetime64[ns]
    2025-11-06T11:35:43.427000064 .....

    standard_name :

    time

    long_name :

    time

    array(['2025-11-06T11:35:43.427000064', '2025-11-06T12:35:43.427000064',
           '2025-11-06T13:35:43.427000064', '2025-11-06T14:35:43.427000064',
           '2025-11-06T15:35:43.427000064', '2025-11-06T16:35:43.427000064',
           '2025-11-06T17:35:43.427000064', '2025-11-06T18:35:43.427000064',
           '2025-11-06T19:35:43.427000064', '2025-11-06T20:35:43.427000064',
           '2025-11-06T21:35:43.427000064', '2025-11-06T22:35:43.427000064',
           '2025-11-06T23:35:43.427000064', '2025-11-07T00:35:43.427000064',
           '2025-11-07T01:35:43.427000064', '2025-11-07T02:35:43.427000064'],
          dtype='datetime64[ns]')

• Data variables: (21)
  • status
    (trajectory, time)
    float64
    ...

    valid_range :

    [0 0]

    flag_values :

    0

    flag_meanings :

    active

    [160000 values with dtype=float64]

  • moving
    (trajectory, time)
    float64
    ...

    minval :

    1

    maxval :

    1

    [160000 values with dtype=float64]

  • age_seconds
    (trajectory, time)
    float32
    ...

    units :

    s

    minval :

    0.0

    maxval :

    54000.0

    [160000 values with dtype=float32]

  • origin_marker
    (trajectory, time)
    float64
    ...

    unit :

    description :

    An integer kept constant during the simulation. Different values may be used for different seedings, to separate elements during analysis. With GUI, only a single seeding is possible.

    flag_values :

    [0 1 2 3 4]

    flag_meanings :

    Lon_4.000000 Lon_4.200000 Lon_4.300000 Lon_4.320000 Lon_4.600000

    minval :

    0

    maxval :

    4

    [160000 values with dtype=float64]

  • lon
    (trajectory, time)
    float32
    ...

    units :

    degrees_east

    standard_name :

    longitude

    long_name :

    longitude

    axis :

    X

    minval :

    3.835968

    maxval :

    4.7932105

    [160000 values with dtype=float32]

  • lat
    (trajectory, time)
    float32
    ...

    units :

    degrees_north

    standard_name :

    latitude

    long_name :

    latitude

    axis :

    Y

    minval :

    59.880264

    maxval :

    60.150818

    [160000 values with dtype=float32]

  • z
    (trajectory, time)
    float32
    ...

    units :

    m

    standard_name :

    z

    long_name :

    vertical position

    axis :

    Z

    positive :

    up

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

  • wind_drift_factor
    (trajectory, time)
    float32
    ...

    units :

    1

    description :

    Elements at surface are moved with this fraction of the vind vector, in addition to currents and Stokes drift

    minval :

    0.02

    maxval :

    0.02

    [160000 values with dtype=float32]

  • current_drift_factor
    (trajectory, time)
    float32
    ...

    units :

    1

    description :

    Elements are moved with this fraction of the current vector, in addition to currents and Stokes drift

    minval :

    1.0

    maxval :

    1.0

    [160000 values with dtype=float32]

  • terminal_velocity
    (trajectory, time)
    float32
    ...

    units :

    m/s

    description :

    Terminal rise/sinking velocity (buoyancy) in the ocean column

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

  • x_sea_water_velocity
    (trajectory, time)
    float32
    ...

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

  • y_sea_water_velocity
    (trajectory, time)
    float32
    ...

    minval :

    0.1

    maxval :

    0.1

    [160000 values with dtype=float32]

  • sea_surface_height
    (trajectory, time)
    float32
    ...

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

  • x_wind
    (trajectory, time)
    float32
    ...

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

  • y_wind
    (trajectory, time)
    float32
    ...

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

  • upward_sea_water_velocity
    (trajectory, time)
    float32
    ...

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

  • sea_surface_wave_significant_height
    (trajectory, time)
    float32
    ...

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

  • sea_surface_wave_stokes_drift_x_velocity
    (trajectory, time)
    float32
    ...

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

  • sea_surface_wave_stokes_drift_y_velocity
    (trajectory, time)
    float32
    ...

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

  • sea_floor_depth_below_sea_level
    (trajectory, time)
    float32
    ...

    minval :

    10000.0

    maxval :

    10000.0

    [160000 values with dtype=float32]

  • land_binary_mask
    (trajectory, time)
    float32
    ...

    minval :

    0.0

    maxval :

    0.0

    [160000 values with dtype=float32]

• Attributes: (119)

  Conventions :

  CF-1.11, ACDD-1.3

  standard_name_vocabulary :

  CF Standard Name Table v85

  featureType :

  trajectory

  title :

  OpenDrift trajectory simulation

  summary :

  Output from simulation with OpenDrift framework

  keywords :

  trajectory, drift, lagrangian, simulation

  history :

  Created 2025-11-06 11:35:47.895086

  date_created :

  2025-11-06T11:35:47.895102

  source :

  Output from simulation with OpenDrift

  model_url :

  https://github.com/OpenDrift/opendrift

  opendrift_class :

  OceanDrift

  opendrift_module :

  opendrift.models.oceandrift

  readers :

  odict_keys(['constant_reader', 'global_landmask'])

  time_coverage_start :

  2025-11-06 11:35:43.427000

  time_step_calculation :

  1:00:00

  time_step_output :

  1:00:00

  config_environment:constant:x_sea_water_velocity :

  None

  config_environment:fallback:x_sea_water_velocity :

  0

  config_environment:constant:y_sea_water_velocity :

  0.1

  config_environment:fallback:y_sea_water_velocity :

  0

  config_environment:constant:sea_surface_height :

  None

  config_environment:fallback:sea_surface_height :

  0

  config_environment:constant:x_wind :

  None

  config_environment:fallback:x_wind :

  0

  config_environment:constant:y_wind :

  None

  config_environment:fallback:y_wind :

  0

  config_environment:constant:upward_sea_water_velocity :

  None

  config_environment:fallback:upward_sea_water_velocity :

  0

  config_environment:constant:ocean_vertical_diffusivity :

  None

  config_environment:fallback:ocean_vertical_diffusivity :

  0

  config_environment:constant:sea_surface_wave_significant_height :

  None

  config_environment:fallback:sea_surface_wave_significant_height :

  0

  config_environment:constant:sea_surface_wave_stokes_drift_x_velocity :

  None

  config_environment:fallback:sea_surface_wave_stokes_drift_x_velocity :

  0

  config_environment:constant:sea_surface_wave_stokes_drift_y_velocity :

  None

  config_environment:fallback:sea_surface_wave_stokes_drift_y_velocity :

  0

  config_environment:constant:ocean_mixed_layer_thickness :

  None

  config_environment:fallback:ocean_mixed_layer_thickness :

  50

  config_environment:constant:sea_floor_depth_below_sea_level :

  None

  config_environment:fallback:sea_floor_depth_below_sea_level :

  10000

  config_environment:constant:land_binary_mask :

  None

  config_environment:fallback:land_binary_mask :

  None

  config_general:use_auto_landmask :

  True

  config_drift:current_uncertainty :

  0

  config_drift:current_uncertainty_uniform :

  0

  config_drift:max_speed :

  2.0

  config_readers:max_number_of_fails :

  1

  config_general:simulation_name :

  config_general:coastline_action :

  stranding

  config_general:coastline_approximation_precision :

  0.001

  config_general:time_step_minutes :

  60

  config_general:time_step_output_minutes :

  None

  config_seed:ocean_only :

  True

  config_seed:number :

  1

  config_drift:max_age_seconds :

  None

  config_drift:advection_scheme :

  euler

  config_drift:horizontal_diffusivity :

  0

  config_drift:profiles_depth :

  50

  config_drift:wind_uncertainty :

  0

  config_drift:relative_wind :

  False

  config_drift:deactivate_north_of :

  None

  config_drift:deactivate_south_of :

  None

  config_drift:deactivate_east_of :

  None

  config_drift:deactivate_west_of :

  None

  config_seed:origin_marker :

  0

  config_seed:z :

  0

  config_seed:wind_drift_factor :

  0.02

  config_seed:current_drift_factor :

  1

  config_seed:terminal_velocity :

  0.0

  config_drift:vertical_advection :

  True

  config_drift:vertical_advection_at_surface :

  False

  config_drift:water_column_stretching :

  False

  config_drift:vertical_advection_correction :

  False

  config_drift:vertical_mixing :

  False

  config_drift:vertical_mixing_at_surface :

  False

  config_vertical_mixing:timestep :

  60

  config_vertical_mixing:diffusivitymodel :

  environment

  config_vertical_mixing:background_diffusivity :

  1.2e-05

  config_vertical_mixing:TSprofiles :

  False

  config_drift:wind_drift_depth :

  0.1

  config_drift:stokes_drift :

  True

  config_drift:stokes_drift_profile :

  Phillips

  config_drift:use_tabularised_stokes_drift :

  False

  config_drift:tabularised_stokes_drift_fetch :

  25000

  config_general:seafloor_action :

  lift_to_seafloor

  config_drift:truncate_ocean_model_below_m :

  None

  config_seed:seafloor :

  False

  opendrift_version :

  1.14.6

  seed_geojson :

  {"features": [], "type": "FeatureCollection"}

  simulation_time :

  2025-11-06 11:35:47.906117

  reader_x_sea_water_velocity :

  0

  reader_y_sea_water_velocity :

  0.1

  reader_sea_surface_height :

  0

  reader_x_wind :

  0

  reader_y_wind :

  0

  reader_upward_sea_water_velocity :

  0

  reader_sea_surface_wave_significant_height :

  0

  reader_sea_surface_wave_stokes_drift_x_velocity :

  0

  reader_sea_surface_wave_stokes_drift_y_velocity :

  0

  reader_sea_floor_depth_below_sea_level :

  10000

  reader_land_binary_mask :

  ['global_landmask']

  time_coverage_end :

  2025-11-07 02:35:43.427000

  time_coverage_duration :

  P0DT15H0M0S

  time_coverage_resolution :

  P0DT1H0M0S

  performance :

  -------------------- Reader performance: -------------------- constant_reader 0:00:00.0 total 0:00:00.0 preparing 0:00:00.0 reading 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: 5.1 total time 4.3 configuration 0.0 preparing main loop 0.0 moving elements to ocean 0.8 main loop 0.0 updating elements 0.0 cleaning up --------------------

  geospatial_bounds_crs :

  EPSG:4326

  geospatial_bounds_vertical_crs :

  EPSG:5831

  geospatial_lat_min :

  59.880264

  geospatial_lat_max :

  60.150818

  geospatial_lat_units :

  degrees_north

  geospatial_lat_resolution :

  point

  geospatial_lon_min :

  3.835968

  geospatial_lon_max :

  4.7932105

  geospatial_lon_units :

  degrees_east

  geospatial_lon_resolution :

  point

  runtime :

  0:00:05.157540

  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'

11:35:49 INFO    opendrift:3916:        calculating for origin_marker 0...
11:35:49 INFO    opendrift:3916:        calculating for origin_marker 1...
11:35:49 INFO    opendrift:3916:        calculating for origin_marker 2...
11:35:49 INFO    opendrift:3916:        calculating for origin_marker 3...
11:35:49 INFO    opendrift:3916:        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)

11:36:01 INFO    opendrift:4636: Saving animation to /root/project/docs/source/gallery/animations/example_dominating_0.gif...
11:36:12 INFO    opendrift:3071: Time to make animation: 0:00:22.456166

os.remove(of)