Mixing down to Mixed Layer Depth

from datetime import datetime, timedelta
from opendrift.models.oceandrift import OceanDrift
from opendrift.readers.reader_constant import Reader as ConstantReader

Mixed Layer Depth of 20m West of 3 deg E, and 50m to the east

r1 = ConstantReader({'ocean_mixed_layer_thickness': 20})
r2 = ConstantReader({'ocean_mixed_layer_thickness': 50})
r1.xmax = 3
r2.xmin = 3

First with Sundby1983 parameterization of diffusivity, based on wind and MLD

o = OceanDrift(loglevel=50)
o.add_reader([r1, r2])
o.set_config('environment:constant:y_wind', 8)  # Some wind for mixing
o.set_config('drift:vertical_mixing', True)
o.set_config('vertical_mixing:diffusivitymodel', 'windspeed_Sundby1983')
# Increasing background diffusivity beyond default (1.2e-5) to avoid artefact due to sharp gradient at MLD
o.set_config('vertical_mixing:background_diffusivity', 0.001)
o.seed_cone(lon=[2, 4], lat=[60, 60], time=datetime.now(), number=5000)
o.run(duration=timedelta(hours=48))
o.animation_profile()

/root/project/opendrift/models/basemodel/__init__.py:3156: UserWarning: No data for colormapping provided via 'c'. Parameters 'cmap' will be ignored
  points = ax.scatter([], [],

Same, but with Large1994 parameterization of diffusivity

o = OceanDrift(loglevel=50)
o.add_reader([r1, r2])
o.set_config('environment:constant:y_wind', 8)  # Some wind for mixing
o.set_config('drift:vertical_mixing', True)
o.set_config('vertical_mixing:diffusivitymodel', 'windspeed_Large1994')
o.set_config('vertical_mixing:background_diffusivity', 0.001)
o.seed_cone(lon=[2, 4], lat=[60, 60], time=datetime.now(), number=5000)
o.run(duration=timedelta(hours=48))
o.animation_profile()

/root/project/opendrift/models/basemodel/__init__.py:3156: UserWarning: No data for colormapping provided via 'c'. Parameters 'cmap' will be ignored
  points = ax.scatter([], [],

Using Large1994, but with 0 diffusivity below MLD

o = OceanDrift(loglevel=50)
o.add_reader([r1, r2])
o.set_config('environment:constant:y_wind', 8)  # Some wind for mixing
o.set_config('drift:vertical_mixing', True)
o.set_config('vertical_mixing:diffusivitymodel', 'windspeed_Large1994')
o.set_config('vertical_mixing:background_diffusivity', 0)
o.seed_cone(lon=[2, 4], lat=[60, 60], time=datetime.now(), number=5000)
o.run(duration=timedelta(hours=48))
o.animation_profile()

/root/project/opendrift/models/basemodel/__init__.py:3156: UserWarning: No data for colormapping provided via 'c'. Parameters 'cmap' will be ignored
  points = ax.scatter([], [],