Choosing a Specific Variable for Simulation in OpenOil

[flaphio]

Hi all,

I've been working on simulating oil spills using OpenOil with Copernicus Marine data on the Brazilian Equatorial Margin. Currently, the simulation automatically selects variables, but I want to take control and manually choose the variables for the simulation. Here's the structure of the Mercator data I'm working with:

Reader: E:/OpenDrift/4. Reader_MEB/mercator/GAF_2023_01.nc
Projection:
+proj=latlong
Coverage: [degrees]
xmin: -55.000000 xmax: -30.000000 step: 0.0833321 numx: 301
ymin: -6.000000 ymax: 6.000000 step: 0.0833335 numy: 144
Corners (lon, lat):
(-55.00, 6.00) (-30.00, 6.00)
(-55.00, -6.00) (-30.00, -6.00)
Vertical levels [m]:
[-0.494025]
Available time range:
start: 2023-01-01 00:30:00 end: 2023-01-31 23:30:00 step: 1:00:00
744 times (0 missing)
Variables:
surface_sea_water_x_velocity
sea_surface_wave_stokes_drift_y_velocity
sea_surface_wave_stokes_drift_x_velocity
northward_sea_water_velocity
surface_sea_water_y_velocity_due_to_tide
eastward_sea_water_velocity
surface_sea_water_x_velocity_due_to_tide
surface_sea_water_y_velocity
y_sea_water_velocity
x_sea_water_velocity
sea_water_speed - derived from ['x_sea_water_velocity', 'y_sea_water_velocity']
sea_surface_wave_stokes_drift_speed - derived from ['sea_surface_wave_stokes_drift_x_velocity', 'sea_surface_wave_stokes_drift_y_velocity']

0:00:45.0 total
0:00:00.9 preparing
0:00:43.9 reading
0:00:06.8 interpolation
0:00:00.2 interpolation_time
0 masking

Currently, the simulation automatically selects variables, but I want to manually configure it. How can I achieve this? Your guidance and suggestions would be greatly appreciated.

Thank you!

[knutfrode]

You can create a reader like normal, and then specify which variables should be used when adding it to the simulation, e.g.
o.add_reader(reader_atmosphere, variables=['x_wind', 'y_wind'])

[flaphio]

I followed your recommendation, but unfortunately, I didn't achieve the desired results. My current challenge involves attempting to access a specific variable from the dataset. Despite my efforts, I'm encountering difficulties in obtaining the expected outcome. Any further guidance or clarification would be greatly appreciated.

The structure of the data is as follows:"

Reader: /home/flavioborges/Documentos/Opendrift/4. Reader_MEB/mercator_data/gaf_wave_202101.nc
Projection:
+proj=latlong
Coverage: [degrees]
xmin: -55.000000 xmax: -30.000000 step: 0.0833321 numx: 301
ymin: -6.000000 ymax: 10.000000 step: 0.0833335 numy: 192
Corners (lon, lat):
(-55.00, 10.00) (-30.00, 10.00)
(-55.00, -6.00) (-30.00, -6.00)
Vertical levels [m]:
[-0.494025]
Available time range:
start: 2021-01-01 00:30:00 end: 2021-01-31 22:30:00 step: 1:00:00
743 times (0 missing)
Variables:
sea_surface_wave_stokes_drift_y_velocity
sea_surface_wave_stokes_drift_x_velocity
northward_sea_water_velocity
eastward_sea_water_velocity
y_sea_water_velocity
x_sea_water_velocity
sea_water_speed - derived from ['x_sea_water_velocity', 'y_sea_water_velocity']
sea_surface_wave_stokes_drift_speed - derived from ['sea_surface_wave_stokes_drift_x_velocity', 'sea_surface_wave_stokes_drift_y_velocity']

I am attempting to access ['sea_surface_wave_stokes_drift_x_velocity', 'sea_surface_wave_stokes_drift_y_velocity'], but I encountered the following issue:

ValueError: Readers must be added for the following required variables: ['x_sea_water_velocity', 'y_sea_water_velocity']

[knutfrode]

It is not totally clear what you are trying to achieve.
A given model needs some certain variables (o.required_variables) to run, e.g. wind (x_wind, y_wind) and current (x_sea_water_velocity, y_sea_water_velocity)
These must be provided by some readers, or you can use constant values: set_config('environment:constant:<variable>, <value>)
It seems that you are trying to start a simulation without adding a reader providing currents?