{
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    {
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      "source": [
        "\n# Double gyre, advection\n\nIllustrating the difference between Euler and Runge-Kutta propagation\nschemes, using an idealised (analytical) eddy current field.\n\nDouble gyre current field from\nhttps://shaddenlab.berkeley.edu/uploads/LCS-tutorial/examples.html\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import numpy as np\nfrom datetime import datetime, timedelta\n\nfrom opendrift.readers import reader_double_gyre\nfrom opendrift.models.oceandrift import OceanDrift\n\ndouble_gyre = reader_double_gyre.Reader(epsilon=.25, omega=0.628, A=0.25)\nduration=timedelta(seconds=6)\nx = [.6]\ny = [.3]\nlon, lat = double_gyre.xy2lonlat(x, y)\n\nruns = []\nleg = []\ni = 0\nfor scheme in ['euler', 'runge-kutta', 'runge-kutta4']:\n    for time_step  in [0.01, 0.1]:\n        leg.append(scheme + ', T=%.2fs' % time_step)\n        print(leg[-1])\n        o = OceanDrift(loglevel=50)\n        o.set_config('environment:fallback:land_binary_mask', 0)\n        o.set_config('drift:advection_scheme', scheme)\n        o.add_reader(double_gyre)\n        o.seed_elements(lon, lat, time=double_gyre.initial_time)\n        o.run(duration=duration, time_step=time_step)\n        runs.append(o)\n        i = i + 1\n\nruns[0].plot(compare=runs[1:], legend=leg, buffer=0.000001, hide_landmask=True)"
      ]
    }
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