Running OceanParcels with surface velocity data from Copernicus.

[claudioiturra]

Hello, I'm new to Ocean-Parcels, sorry! I'm currently attempting to run a Lagrangian particle distribution using velocities from Copernicus (.nc file). Here is my code. The .nc file contains the variables uo, vo, longitude, latitude, and time (hours since 1950-01-01, 2137hours). As described in the code, I got the error in the runtime and field sampe out of bond, I will appreciate any suggestion, is actually de code right?.

FieldOutOfBoundError Traceback (most recent call last)
Cell In[7], line 7
1 output_file = pset.ParticleFile(
2 name="GCParticles.zarr", # the name of the output file
3 outputdt=3600, # the time period between consecutive out output steps
4 chunks=(1, 10), # the chunking of the output file (number of particles, timesteps)
5 )
----> 7 pset.execute(
8 kernels, # the kernel (which defines how particles move)
9 runtime=86400 * 24, # the total length of the run in seconds
10 dt=300, # the timestep of the kernel in seconds
11 output_file=output_file,
12 )

File /opt/anaconda3/envs/parcels/lib/python3.12/site-packages/parcels/particleset.py:951, in ParticleSet.execute(self, pyfunc, pyfunc_inter, endtime, runtime, dt, output_file, verbose_progress, postIterationCallbacks, callbackdt)
949 # If we don't perform interaction, only execute the normal kernel efficiently.
950 if self.interaction_kernel is None:
--> 951 res = self.kernel.execute(self, endtime=next_time, dt=dt)
952 if res == StatusCode.StopAllExecution:
953 return StatusCode.StopAllExecution

File /opt/anaconda3/envs/parcels/lib/python3.12/site-packages/parcels/kernel.py:585, in Kernel.execute(self, pset, endtime, dt)
583 raise TimeExtrapolationError(p.time)
584 elif p.state == StatusCode.ErrorOutOfBounds:
--> 585 raise FieldOutOfBoundError(p.lon, p.lat, p.depth)
586 elif p.state == StatusCode.ErrorThroughSurface:
587 raise FieldOutOfBoundSurfaceError(p.lon, p.lat, p.depth)

FieldOutOfBoundError: Field sampled out-of-bound, at (-73.2887954711914, -37.59098434448242, 0.0)

Variables:
uo
Size: 21x28x1x8748
Dimensions: longitude,latitude,depth,time
Datatype: single
Attributes:

[erikvansebille]

Hi @claudioiturra, thanks for using Parcels!

Your error is a FieldOutOfBoundError, which means that you try to access a location in the ocean (in your case 73W, 37S) that is not part of the domain. See this part of the tutorial on how to work with this and other ErrorCodes

[claudioiturra]

Hi @michaeldenes , yes.. thank you so much! Actually I was learning about kernels during the night, now everything works great. Such a great tool, Im currently learning a lot using the tutorial. Thanks again.

[claudioiturra]

Hello again! Well... thank you soooooo much for all the help @michaeldenes @erikvansebille ! Now I have the last one! I'm not that good with Python. I will appreciate any help on how to plot each trajectory with different colors and add a point at a specific location.

ds = xr.open_zarr("JAN2023GULFARAUCO.zarr")
ds.traj.plot(margin=2)
#x = [-73.1224]
#y = [-36.4075]
#plt.show() Did not work
plt.plot(x, y, marker="o", markersize=20, markeredgecolor="red", markerfacecolor="green")

Thank for your time guys...

[michaeldenes]

Hi @claudioiturra, no problem, we're glad you're enjoying using the tool. There's quite a few tutorials on our webpage (see, https://docs.oceanparcels.org/en/latest/documentation.html ), but the specific one that might help you is https://docs.oceanparcels.org/en/latest/examples/tutorial_output.html .

Specifically, if ds is your trajectory data, then the following should work nicely:
plt.plot(ds["lon"].T, ds["lat"].T)

To plot a point at a specific location (e.g., the start points of the trajectories), you can do a simple scatter plot similar to above. But all of this is can be determined from the tutorial.

Cheers!

[claudioiturra]

Thanks @michaeldenes , finally I solve that with a for. Looks great!

[michaeldenes]

@claudioiturra Perfect! Happy to have helped :)