Merge pull request #1650 from knutfrode/dev

[run-ex] Adding example illustrating custom shape landmask reader for…

Author: knutfrode

examples/example_lake.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python
+"""
+Caspian / lake
+===============
+"""
+
+from datetime import datetime, timedelta
+from opendrift.models.oceandrift import OceanDrift
+from opendrift.readers import reader_shape
+import cartopy
+
+#%%
+# The default GSHHG landmask reader classifies lakes
+# (e.g. Caspian Sea) as land and not water.
+# For simulations in lakes, we can use a custom reader for lakes only.
+level = 'h'  # using high resolution coastline
+reader_lakes = reader_shape.Reader.from_shpfiles(
+    f'{cartopy.config['data_dir']}/shapefiles/gshhs/{level}/GSHHS_{level}_L2.shp',
+    invert=True)  # Inverting since inside of polygons is water (lake) and not land.
+
+#%%
+# Disabling the default landmask reader, and using the above reader instead
+o = OceanDrift(loglevel=20)
+o.add_reader(reader_lakes)
+o.set_config('general:use_auto_landmask', False)  # To use custom landmask instead
+o.set_config('environment:constant:x_sea_water_velocity', 1)
+o.set_config('drift:horizontal_diffusivity', 100)
+o.seed_elements(lon=48.819, lat=44.959, radius=5000, number=100, time=datetime.now())
+
+o.run(steps=10)
+o.plot(fast=False, buffer=2)