Source code for opendrift.models.leeway

# This file is part of OpenDrift.
# OpenDrift is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 2
# OpenDrift is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with OpenDrift.  If not, see <>.
# Copyright 2015, Knut-Frode Dagestad, MET Norway

Leeway is the search and rescue (SAR) model developed by the US Coast Guard, as originally described in

    Allen, A.A, 2005: Leeway Divergence, USCG R&D Center Technical Report CG-D-05-05. Available through, reference ADA435435 

    Allen A.A. and J.V. Plourde (1999) Review of Leeway; Field Experiments and Implementation, USCG R&D Center Technical Report CG-D-08-99. Available through, reference ADA366414

and later extended and modified by e.g.

    Breivik, O., A. Allen, C. Maisondieu, J.-C. Roth, and B. Forest, 2012: The leeway of shipping containers at different immersion levels. Ocean Dyn., 62, 741–752, doi:10.1007/s10236-012-0522-z

The Leeway model is based on empirically determined coefficients as tabulated in

The Leeway model is been reprogrammed in Python for OpenDrift by Knut-Frode Dagestad of the Norwegian Meteorological Institute.

from builtins import range
import os
from collections import OrderedDict
import logging; logger = logging.getLogger(__name__)

import numpy as np

from opendrift.models.basemodel import OpenDriftSimulation
from opendrift.elements import LagrangianArray

LEFT = 1

# Defining the leeway element properties
[docs]class LeewayObj(LagrangianArray): """Extending LagrangianArray with variables relevant for leeway objects. """ variables = LagrangianArray.add_variables([ ('object_type', {'dtype': np.uint16, 'units': '1', 'seed': False, 'default': 0}), ('orientation', {'dtype': np.uint8, 'units': '1', 'description': '0/1 is left/right of downwind. Randomly chosen at seed time', 'seed': False, 'default': 1}), ('jibe_probability', {'dtype': np.float32, 'units': '1/h', 'description': 'Probability per hour that an object may change orientation (jibing)', 'default': 0.04}), ('downwind_slope', {'dtype': np.float32, 'units': '%', 'seed': False, 'default': 1}), ('crosswind_slope', {'dtype': np.float32, 'units': '1', 'seed': False, 'default': 1}), ('downwind_offset', {'dtype': np.float32, 'units': 'cm/s', 'seed': False, 'default': 0}), ('crosswind_offset', {'dtype': np.float32, 'units': 'cm/s', 'seed': False, 'default': 0}), ('downwind_eps', {'dtype': np.float32, 'units': 'cm/s', 'seed': False, 'default': 0}), ('crosswind_eps', {'dtype': np.float32, 'units': 'cm/s', 'seed': False, 'default': 0}) ])
[docs]class Leeway(OpenDriftSimulation): """The Leeway model in the OpenDrift framework. Advects a particle (a drifting object) with the ambient current and as a function of the wind vector according to the drift properties of the object. """ ElementType = LeewayObj required_variables = { 'x_wind': {'fallback': None}, 'y_wind': {'fallback': None}, 'x_sea_water_velocity': {'fallback': None}, 'y_sea_water_velocity': {'fallback': None}, 'land_binary_mask': {'fallback': None}, } # Default colors for plotting status_colors = {'initial': 'green', 'active': 'blue', 'missing_data': 'gray', 'stranded': 'red', 'evaporated': 'yellow', 'dispersed': 'magenta'} max_speed = 1.5 # Assumed max average speed of any element # Configuration def __init__(self, d=None, *args, **kwargs): # Read leeway object properties from file if d is None: d = os.path.dirname(os.path.realpath(__file__)) objprop_file = open(d + '/OBJECTPROP.DAT', 'r') else: objprop_file = open(d, 'r') # objprop_file=open('/home/oyvindb/Pro/opendrift/OBJECTPROP.DAT','r') objproptxt = objprop_file.readlines() objprop_file.close() self.leewayprop = OrderedDict({}) for i in range(len(objproptxt)//3+1): # Stop at first blank line if not objproptxt[i*3].strip(): break elems = objproptxt[i*3].split()[0] objKey = objproptxt[i*3].split()[0].strip() arr = [float(x) for x in objproptxt[i*3+2].split()] props = {'OBJKEY': objKey} props['Description'] = objproptxt[i*3+1].strip() props['DWSLOPE'] = arr[0] props['DWOFFSET'] = arr[1] props['DWSTD'] = arr[2] props['CWRSLOPE'] = arr[3] props['CWROFFSET'] = arr[4] props['CWRSTD'] = arr[5] props['CWLSLOPE'] = arr[6] props['CWLOFFSET'] = arr[7] props['CWLSTD'] = arr[8] self.leewayprop[i+1] = props # Config descriptions = [self.leewayprop[p]['Description'] for p in self.leewayprop] # Calling general constructor of parent class super(Leeway, self).__init__(*args, **kwargs) self._add_config({ 'seed:object_type': {'type': 'enum', 'enum': descriptions, 'default': descriptions[0], 'description': 'Leeway object category for this simulation', 'level': self.CONFIG_LEVEL_ESSENTIAL}, 'seed:jibe_probability': {'type': 'float', 'default': 0.04, 'min': 0, 'max': 1, 'description': 'Probability per hour for jibing (objects changing orientation)', 'units': 'probability', 'level': self.CONFIG_LEVEL_BASIC}, }) self._set_config_default('general:time_step_minutes', 10) self._set_config_default('general:time_step_output_minutes', 60)
[docs] def seed_elements(self, lon, lat, object_type=None, **kwargs): """Seed particles in a cone-shaped area over a time period.""" # All particles carry their own object_type (number), # but so far we only use one for each sim # objtype = np.ones(number)*object_type if 'number' in kwargs and kwargs['number'] is not None: number = kwargs['number'] else: number = self.get_config('seed:number') if object_type is None: object_name = self.get_config('seed:object_type') # Get number from name found = False for object_type in range(1, len(self.leewayprop)+1): if self.leewayprop[object_type]['OBJKEY'] == object_name or( self.leewayprop[object_type]['Description'] == object_name): found = True break if found is False: raise ValueError('Object %s not available' % object_type)'Seeding elements of object type %i: %s (%s)' % (object_type, self.leewayprop[object_type]['OBJKEY'], self.leewayprop[object_type]['Description'])) # Drift orientation of particles. 0 is right of downwind, # 1 is left of downwind # orientation = 1*(np.random.rand(number)>=0.5) # Odd numbered particles are left-drifting, even are right of downwind. orientation = np.r_[:number] % 2 ones = np.ones_like(orientation) # Downwind leeway properties. # Generate normal, N(0,1), random perturbations for leeway coeffs. # Negative downwind slope must be avoided as # particles should drift downwind. # The problem arises because of high error variances (see e.g. PIW-1). downwind_slope = ones*self.leewayprop[object_type]['DWSLOPE'] downwind_offset = ones*self.leewayprop[object_type]['DWOFFSET'] dwstd = self.leewayprop[object_type]['DWSTD'] rdw = np.zeros(number) epsdw = np.zeros(number) for i in range(number): rdw[i] = np.random.randn(1) epsdw[i] = rdw[i]*dwstd # Avoid negative downwind slopes while downwind_slope[i] + epsdw[i]/20.0 < 0.0: rdw[i] = np.random.randn(1) epsdw[i] = rdw[i]*dwstd downwind_eps = epsdw # NB # downwind_eps = np.zeros(number) # Crosswind leeway properties rcw = np.random.randn(number) crosswind_slope = np.zeros(number) crosswind_offset = np.zeros(number) crosswind_eps = np.zeros(number) crosswind_slope[orientation == RIGHT] = \ self.leewayprop[object_type]['CWRSLOPE'] crosswind_slope[orientation == LEFT] = \ self.leewayprop[object_type]['CWLSLOPE'] crosswind_offset[orientation == RIGHT] = \ self.leewayprop[object_type]['CWROFFSET'] crosswind_offset[orientation == LEFT] = \ self.leewayprop[object_type]['CWLOFFSET'] crosswind_eps[orientation == RIGHT] = \ rcw[orientation == RIGHT] * \ self.leewayprop[object_type]['CWRSTD'] crosswind_eps[orientation == LEFT] = \ rcw[orientation == LEFT] * \ self.leewayprop[object_type]['CWLSTD'] # NB # crosswind_eps = np.zeros(number) # Store seed data for ASCII format output if hasattr(self, 'seed_cone_arguments'): self.ascii = self.seed_cone_arguments else: self.ascii = {'lon': lon, 'lat': lat, 'radius': kwargs['radius'] if 'radius' in kwargs else 0, 'number': number, 'time': kwargs['time']} # Call general seed_elements function of OpenDriftSimulation class # with the specific values calculated super(Leeway, self).seed_elements(lon, lat, orientation=orientation, object_type=object_type, downwind_slope=downwind_slope, crosswind_slope=crosswind_slope, downwind_offset=downwind_offset, crosswind_offset=crosswind_offset, downwind_eps=downwind_eps, crosswind_eps=crosswind_eps, **kwargs)
[docs] def list_object_categories(self, substr=None): '''Display leeway categories to screen Print only objects containing 'substr', if specified''' for i, p in enumerate(self.leewayprop): description = self.leewayprop[p]['Description'] objkey = self.leewayprop[p]['OBJKEY'] if substr is not None: if substr.lower() not in description.lower() + objkey.lower(): continue print('%i %s %s' % (i+1, objkey, description))
[docs] def update(self): """Update positions and properties of leeway particles.""" windspeed = np.sqrt(self.environment.x_wind**2 + self.environment.y_wind**2) # CCC update wind direction winddir = np.arctan2(self.environment.x_wind, self.environment.y_wind) # Move particles with the leeway CCC TODO downwind_leeway = ((self.elements.downwind_slope + self.elements.downwind_eps/20.0)*windspeed + self.elements.downwind_offset + self.elements.downwind_eps/2.0)*.01 # In m/s crosswind_leeway = ((self.elements.crosswind_slope + self.elements.crosswind_eps/20.0)*windspeed + self.elements.crosswind_offset + self.elements.crosswind_eps/2.0)*.01 # In m/s sinth = np.sin(winddir) costh = np.cos(winddir) y_leeway = downwind_leeway*costh+crosswind_leeway*sinth x_leeway = -downwind_leeway*sinth+crosswind_leeway*costh self.update_positions(-x_leeway, y_leeway) # Move particles with ambient current self.update_positions(self.environment.x_sea_water_velocity, self.environment.y_sea_water_velocity) # Jibe elements randomly according to given probability jibe_rate = -np.log(1-self.elements.jibe_probability)/3600 # Hourly to instantaneous jp_per_timestep = 1 - np.exp(-jibe_rate*np.abs(self.time_step.total_seconds())) jib = jp_per_timestep > np.random.random(self.num_elements_active()) self.elements.crosswind_slope[jib] = - self.elements.crosswind_slope[jib] self.elements.orientation[jib] = 1 - self.elements.orientation[jib] logger.debug('Jibing %i out of %i elements.' % (np.sum(jib), self.num_elements_active()))
[docs] def export_ascii(self, filename): '''Export output to ASCII format of original version''' try: f = open(filename, 'w') except: raise ValueError('Could not open file for writing: ' + filename) start_time = self.start_time for inp in ['lon', 'lat', 'radius', 'time']: if len(np.atleast_1d(self.ascii[inp])) == 1: self.ascii[inp] = [self.ascii[inp], self.ascii[inp]] f.write('# Drift simulation initiated [UTC]:\n') f.write('simDate simTime\n') f.write(self.start_time.strftime('%Y-%m-%d\t%H:%M:%S\t#\n')) f.write( '# Model version:\n' 'modelVersion\n' ' 3.00\n' # OpenDrift version '# Object class id & name:\n' 'objectClassId objectClassName\n') try: objtype = self.elements.object_type[0] except: objtype = self.elements_deactivated.object_type[0] f.write(' %i\t%s\n' % (objtype, self.leewayprop[objtype]['OBJKEY'])) f.write( '# Seeding start time, position & radius:\n' 'startDate\tstartTime\tstartLon\tstartLat\tstartRad\n') f.write('%s\t%s\t%s\t%s\n' % ( self.ascii['time'][0], self.ascii['lon'][0], self.ascii['lat'][0], self.ascii['radius'][0]/1000.)) f.write( '# Seeding end time, position & radius:\n' 'endDate\tendTime\tendLon\tendLat\tendRad\n') f.write('%s\t%s\t%s\t%s\n' % ( self.ascii['time'][1], self.ascii['lon'][1], self.ascii['lat'][1], self.ascii['radius'][1]/1000.)) seedDuration = (self.ascii['time'][1]-self.ascii['time'][0]).total_seconds()/60. seedSteps=seedDuration/(self.time_step_output.total_seconds()/60.) seedSteps = np.maximum(1, seedSteps) f.write( '# Duration of seeding [min] & [timesteps]:\n' 'seedDuration seedSteps\n' ' %i %i\n' '# Length of timestep [min]:\n' 'timeStep\n' % (seedDuration, seedSteps)) f.write('%i\n' % (self.time_step_output.total_seconds()/60.)) f.write( '# Length of model simulation [min] & [timesteps]:\n' 'simLength simSteps\n') f.write('%i\t%i\n' % ((self.time - self.start_time).total_seconds()/60., self.steps_output)) f.write( '# Total no of seeded particles:\n' 'seedTotal\n' ' %s\n' % (self.num_elements_activated())) f.write( '# Particles seeded per timestep:\n' 'seedRate\n' ' %i\n' % (self.num_elements_activated()/seedSteps)) index_of_first, index_of_last = \ self.index_of_activation_and_deactivation() beforeseeded = 0 lons, statuss = self.get_property('lon') lats, statuss = self.get_property('lat') orientations, statuss = self.get_property('orientation') for step in range(self.steps_output): lon = lons[step,:] lat = lats[step,:] orientation = orientations[step,:] status = statuss[step,:] if sum(status==0) == 0: # All elements deactivated: using last position lon = lons[step-1,:] lat = lats[step-1,:] orientation = orientations[step-1,:] status = statuss[step-1,:] num_active = np.sum(~status.mask) status[status.mask] = 41 # seeded on land lon[status.mask] = 0 lat[status.mask] = 0 orientation[status.mask] = 0 status[status==0] = 11 # active status[status==1] = 41 # stranded ID = np.arange(0, num_active+1) f.write('\n# Date [UTC]:\nnowDate nowTime\n') f.write((self.start_time + self.time_step_output*step).strftime('%Y-%m-%d\t%H:%M:%S\n')) f.write('# Time passed [min] & [timesteps], now seeded, seeded so far:\ntimePassed nStep nowSeeded nSeeded\n') f.write(' %i\t%i\t%i\t%i\n' % ( (self.time_step_output*step).total_seconds()/60, step+1, num_active-beforeseeded, num_active)) beforeseeded = num_active f.write('# Mean position:\nmeanLon meanLat\n') f.write('%f\t%f\n' % (np.mean(lon[status==11]), np.mean(lat[status==11]))) f.write('# Particle data:\n') f.write('id lon lat state age orientation\n') age_minutes = self.time_step_output.total_seconds()*( step - index_of_first)/60 age_minutes[age_minutes<0] = 0 for i in range(num_active): f.write('%i\t%s\t%s\t%i\t%i\t%i\n' % (i+1, lon[i], lat[i], status[i], age_minutes[i], orientation[i])) f.close()
[docs] def _substance_name(self): # TODO: find a better algorithm to return name of object category if hasattr(self, 'history'): object_type = self.history['object_type'][0,0] if not np.isfinite(object_type): # For backward simulations object_type = self.history['object_type'][-1,0] else: object_type = np.atleast_1d(self.elements_scheduled.object_type)[0] if np.isfinite(object_type): return self.leewayprop[object_type]['OBJKEY'] else: return ''