# Copyright 2022 – present, UBC EOAS MOAD Group and The University of British Columbia
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
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# distributed under the License is distributed on an "AS IS" BASIS,
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# See the License for the specific language governing permissions and
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# SPDX-License-Identifier: Apache-2.0
# SPDX-License-Identifier: Apache-2.0
[docs]
def Stokes_drift(particle, fieldset, time):
"""Include the effect of Stokes drift to your particles
trajectory using WaveWatch3 data.
This kernel is intended for use as a particle behaviour kernel
Example usage:
.. code-block:: python
from moacean_parcels.kernels import Stokes_drift
# ...
Sd_kernel = pset.Kernel(Stokes_drift)
# ...
pset.execute(kernels ... + Sd_kernel,
# ...
)
For a more detailed usage example,
please see the example notebook for this kernel in the
:ref:`particle_behaviour_kernels` section.
:param particle: Particle to add behaviour.
:type particle: :py:class:`parcels.particle.JITParticle` or
:py:class:`parcels.particle.ScipyInteractionParticle`
:param fieldset: Hydrodynamic fields that is moving the particle.
:type fieldset: :py:class:`parcels.fieldset.FieldSet`
:param time: Current time of the particle.
:type time: :py:attr:`numpy.float64`"""
Sd_lat = particle.lat
if Sd_lat > 48 and Sd_lat < 51: # Check that particle is inside WW3 data field
Sd_deg2m = 111319.5
Sd_lonc = cos((Sd_lat * math.pi) / 180)
(Sd_u, Sd_v, Sd_wl) = fieldset.stokes[
time, particle.depth, particle.lat, particle.lon
]
k = (2 * math.pi) / Sd_wl
Sd_u = (Sd_u * exp(-abs(2 * k * particle.depth))) / (Sd_deg2m * Sd_lonc)
Sd_v = (Sd_v * exp(-abs(2 * k * particle.depth))) / Sd_deg2m
particle.lon += Sd_u * particle.dt
particle.lat += Sd_v * particle.dt