Contents
How big is the latitude and longitude variable in netCDF?
Most imporantly, it tells us the names of the variable in the NetCDF file, and also includes notes about the units of each variable. Notice the Size of each variable. That’s usually a first clue into how the data matrices are organized. The longitude variable is 480×1, latitude is 241×1, and time is 12×1.
Is there a way to read a netCDF file?
There is a public domain filter for output from the ncdump utility, called read.ncdump, available here . It understands the UDUNITS dates in our files and translates them to a human readable output. The ncdump utility is handy for taking a quick look at the file metadata and coordinate values, and is available as part of the standard NetCDF suite .
How to open and process netCDF 4 data format in open?
You will use the xarray package which requires the netcdf4 package to work with netcdf data. The most current earth-analytics-python environment contains all of the packages that you need to complete this tutorial.
How to work with netCDF data in HDF5?
The syntax of working with HDF5 may be slightly different from NetCDF, but the general idea is typically the same. Instead of ncdisp to display the contents of a file, use h5disp. Instead of ncread, use h5read. And instead of the CDT function ncstruct to read data into a structure forma, use the CDT function h5struct.
What does the ncread function do in netCDF?
The ncread function lets us specify which indices of data to load, and the format it wants is start and stride, meaning the starting indices of each dimension, and how many rows or columns of data to load starting at the start indices.
How are data values accessed in netCDF file?
The netCDF interface supports several forms of direct access to data values in an open netCDF file. We describe each of these forms of access in order of increasing generality: access to individual elements, specified with an index vector; access to array sections, specified with an index vector, and count vector;
What’s the difference between NetCDF and HDF5?
Most of the principles described above also apply to the HDF5, which is a hierarchical data format that is quite similar to NetCDF. The syntax of working with HDF5 may be slightly different from NetCDF, but the general idea is typically the same. Instead of ncdisp to display the contents of a file, use h5disp. Instead of ncread, use h5read.
How to get netCDF data from ECMWF?
Select NetCDF data format and download at the default 0.75×0.75 degree resolution. Wait about 15 minutes for the data to be ready and download it. The default filenames for data downloaded from ECMWF are often long and cryptic, so for this tutorial I renamed it ERA_Interim_2017.nc.