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%matplotlib inline


    

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import numpy as np
import matplotlib.tri as tri
import matplotlib.pyplot as plt
import datetime as dt
import netCDF4
import numpy as np


    

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import cartopy.crs as ccrs
from cartopy.io.img_tiles import MapQuestOpenAerial, MapQuestOSM, OSM


    

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import iris
import pyugrid


    

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iris.FUTURE.netcdf_promote = True


    

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# UMASSD/SMAST FVCOM Simulations in support of Water Quality for MWRA
url = 'http://www.smast.umassd.edu:8080/thredds/dodsC/fvcom/mwra/fvcom'
var = 'sea_water_salinity'    # use standard_name if it exists
levs = np.arange(28.,33.5,.1)   # contour levels for plotting
bbox = [-71.5, -70, 41.5, 43]
klev = 0   # level 0 is top in FVCOM

# time relative to now
start = dt.datetime.utcnow() + dt.timedelta(hours=6)
# or specific time (UTC)
start = dt.datetime(1998,3,2,15,0,0)


    

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cube = iris.load_cube(url,var)    # Iris uses the standard_name or long_name to access variables


    

    




/home/usgs/miniconda/envs/ioos/lib/python2.7/site-packages/iris/fileformats/cf.py:552: UserWarning: Missing CF-netCDF formula term variable u'depth', referenced by netCDF variable u'siglev'
  warnings.warn(message % (variable_name, nc_var_name))
/home/usgs/miniconda/envs/ioos/lib/python2.7/site-packages/iris/fileformats/cf.py:1006: UserWarning: Ignoring variable u'siglay' referenced by variable u'v': Dimensions (u'siglay', u'node') do not span (u'time', u'siglay', u'nele')
  warnings.warn(msg)
/home/usgs/miniconda/envs/ioos/lib/python2.7/site-packages/iris/fileformats/cf.py:1006: UserWarning: Ignoring variable u'siglay' referenced by variable u'ww': Dimensions (u'siglay', u'node') do not span (u'time', u'siglay', u'nele')
  warnings.warn(msg)
/home/usgs/miniconda/envs/ioos/lib/python2.7/site-packages/iris/fileformats/cf.py:1006: UserWarning: Ignoring variable u'siglay' referenced by variable u'u': Dimensions (u'siglay', u'node') do not span (u'time', u'siglay', u'nele')
  warnings.warn(msg)
/home/usgs/miniconda/envs/ioos/lib/python2.7/site-packages/iris/fileformats/_pyke_rules/compiled_krb/fc_rules_cf_fc.py:1300: UserWarning: Ignoring netCDF variable u'wts' invalid units u'UDUNITS compatible units'
  warnings.warn(msg.encode('ascii', errors='backslashreplace'))

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ug = pyugrid.UGrid.from_ncfile(url)

cube.mesh = ug
cube.mesh_dimension = 1  # (0:time,1:node)
lon = cube.mesh.nodes[:,0]
lat = cube.mesh.nodes[:,1]
nv = cube.mesh.faces
triang = tri.Triangulation(lon,lat,triangles=nv)


    

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nc = netCDF4.Dataset(url).variables
time_var = nc['time']
itime = netCDF4.date2index(start,time_var,select='nearest')


    

    




---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-13-812782796376> in <module>()
      1 nc = netCDF4.Dataset(url).variables
      2 time_var = nc['time']
----> 3 itime = netCDF4.date2index(start,time_var,select='nearest')

NameError: name 'start' is not defined

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zcube = cube[itime, klev, :]


    

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geodetic = ccrs.Geodetic(globe=ccrs.Globe(datum='WGS84'))

fig = plt.figure(figsize=(8,8))
tiler = MapQuestOpenAerial()
ax = plt.axes(projection=tiler.crs)

#ax = plt.axes(projection=ccrs.PlateCarree())
ax.set_extent(bbox,geodetic)
ax.add_image(tiler, 8)

#ax.coastlines()
plt.tricontourf(triang, zcube.data, levels=levs, transform=geodetic)
plt.colorbar()
plt.tricontour(triang, zcube.data, colors='k',levels=levs, transform=geodetic)
tvar = cube.coord('time')
tstr = tvar.units.num2date(tvar.points[itime])
gl = ax.gridlines(draw_labels=True)
gl.xlabels_top = False
gl.ylabels_right = False
plt.title('%s: %s: %s' % (zcube.attributes['title'],var,tstr));


    

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