netCDF4.Dataset, I don't get an error. Make sure your installation of netcdf4 and libnetcdf are up to date. Since this isn't a MetPy problem, if you have additional problems, they'd be best reported on the netcdf4-python issue tracker so that the right people see the report.
azimuth_range_to_lat_lon--you only need to convert the x/y values to az/range values.
Level3File for us to go ahead and do that behind the scenes for you (as part of our much needed cleanup of NEXRAD stuff #49)
DS.58sti). I'm able to get the current position of the storms and their projected track - however it doesn't seem to have any more information besides the storm ID. Are you guys currently parsing more data such as azimuth, range, psh, poh, vil, max_dbz, sknt, etc? So far the only way that I have been able to remotely see this information is to use the tab page - but in the source code it looks like some of this information is already being parsed (https://github.com/Unidata/MetPy/blob/3adfbd81629f0915f8d53e1e7b2509b2628827ca/src/metpy/io/nexrad.py#L2015) - I'm just not sure how to get to it. I'd be willing to write some documentation on the NEXRAD stuff as soon as I can piece it all together.
Hello! I've been using the 500mb vorticity advection example in a jupyter notebook. Using siphon.ncss, I can get the latest NAM 12km model to draw the chart correctly. However, when I switch it over to the GFS, I get an error here:
dx_, dy_ = mpcalc.lat_lon_grid_deltas(lon, lat)
f = mpcalc.coriolis_parameter(np.deg2rad(lat)).to(units('1/sec'))
avor = mpcalc.vorticity(uwnd_500, vwnd_500, dx=dx_, dy=dy_) + f
avor = ndimage.gaussian_filter(avor, sigma=3, order=0) * units('1/s')
vort_adv = mpcalc.advection(avor, u=uwnd_500, v=vwnd_500, dx=dx_, dy=dy_) * 1e9at mpcalc.vorticity:
ValueError: operands could not be broadcast together with shapes (721,1440) (721,)
@potion-cellar It looks like your input shapes are not broadcasting together appropriately. Quickest fix without changing your workflow is to insert size one dimensions (... + f[:, None] on that vorticity line should do it) to manually fix the broadcasting. Otherwise, if you're on MetPy v1.0 and using xarray, a lot of this becomes easier:
avor = mpcalc.absolute_vorticity(uwnd_500, vwnd_500)
avor_smoothed = mpcalc.smooth_gaussian(avor, n=19)
vort_adv = mpcalc.advection(avor_smoothed, u=uwnd_500, v=vwnd_500)since all the grid deltas and coriolis parameter information is determined automatically from the coordinates.
pressure (or the vertical coordinate) first, then all the other data variables, then options. precipitable_water was the outlier by originally being (dewpt, pressure).
graph_pages and tab_pages attributes in the file. That's because that information is encoded as graphical information or literal text pages. We have not tried to parse those and present that information.
@jthielen Thanks Jon!
I have another question. I have a lot of workflows set up now and everything is looking great, but one thing I haven't been able to figure out is how to get a value of a variable (lets say temperature @ 2m) for a given coordinate. I'm generally just plotting contours of variables like temperature = units.kelvin * raw_dataset.variables['name_of_the_temperature_var'][:, 0, :, :] where raw_dataset is the output from siphon's ncss.get_data().
I know how to access the data (in terms of specific time and level) for anything except a specific lat/lon, since for most variables it appears lat and lon are both 2d arrays due to the projection, so I have no idea how to traverse these arrays to get the actual value that would pertain to a coordinate.
data_crs.transform_point(ccrs.PlateCarree(), lon, lat) with cartopy...can also do with pyproj), and then indexing based on those 1D x and y coordinates. It's been awhile since I haven't used xarray, so I'm not sure what that latter part looks like in a netCDF4 Dataset-based workflow...it's very easy with xarray (ds.sel(x=x, y=y, method='nearest')).
PlotObs, even after following the MetPy Mondays #115 - Declarative Station Plots tutorial 100% (I verified this). When setting obs.time before plotting the obs, pandas throws a KeyError in regards to the datetime. Omitting that statement otherwise causes things to be plotted properly. Not sure if it's a dependency issue since that tutorial is over a year old or we should file an issue through more formal channels.
@winash12 Not currently. According to that definition you linked to:
Horizontal wind shear of such a nature that it contributes to the cyclonic vorticity of the flow, that is, it tends to produce cyclonic rotation of the individual air particles along the line of flow.
So in the use case you're imagining, how are you defining "line of flow"?