# ******************* track drift of neutrally bouyant particles **************************
# get modules 
from opendrift.readers import reader_netCDF_CF_generic
from opendrift.models.oceandrift import OceanDrift
from datetime import timedelta, datetime

# get readers
reader_norkyst = reader_netCDF_CF_generic.Reader('https://thredds.met.no/thredds/dodsC/sea/norkyst800m/1h/aggregate_be')
reader_nordic = reader_netCDF_CF_generic.Reader('https://thredds.met.no/thredds/dodsC/sea/nordic4km/zdepths1h/aggregate_be')

# get python package
import numpy as np

# code for initializing and seedin particles
# set number of particles
n=100000 

# distribute randomly from 0 to 100 m depth			
z = -np.random.rand(n)*100 	

# choose drift module
o = OceanDrift(loglevel=20)
o.add_reader([reader_norkyst, reader_nordic])

# seed particles at lat/lon location within radius (in meters) and over time window 
o.seed_elements(lon=8.3, lat=58.05, z=z, radius=100, number=n, time=datetime(2020,1,1))
 time=[datetime(2019,12,15), datetime(2020,1,15)])

# set rule for particles stranding on land
o.set_config('general:coastline_action', 'previous')

# run model, set variables to store and output file
o.run(duration=timedelta(days=300), time_step=3600, time_step_output=3600,
    export_variables=['lat','lon', 'z', 'time'], outfile='out.nc')