Problems with NOAA NDFD data

[dopplershift]

When opening some NDFD (National Digital Forecast Database) data from NOAA like:

from urllib.request import urlopen

import matplotlib.pyplot as plt
import xarray as xr

url = 'https://noaa-ndfd-pds.s3.amazonaws.com/opnl/AR.conus/VP.001-003/ds.temp.bin'
fname = 'forecast.bin'
with open(fname, 'wb') as cache_file:
    cache_file.write(urlopen(url).read())

ds = xr.open_dataset(fname, engine='cfgrib')
plt.imshow(ds.t2m[0])

The result is:

This contrasts with the same message opened with pygrib:

import pygrib
grb = pygrib.open(fname)
msg = grb.message(1)
plt.imshow(msg.values)

This seems to be caused by the fact that the "alternativeRowScanning" key is not considered at all by cfgrib, and it is set for this data:

>>> print(msg['alternativeRowScanning'])
1

[shahramn]

Which version of the ecCodes library are you using? I just tried the Geoiterator on the first message of the file ds.temp.bin and it looks fine ( I am using ecCodes v2.25.0 )

[dopplershift]

That's interesting. I have eccodes 2.25.0 installed, and I still had problems when going through cfgrib. I'll continue the discussion over on #296 .

[iainrussell]

Fixed with #296