2. Accessing ARP data

2.1. THREDDS server

Data are stored as netCDF files (netCDF 3 classic 64-bit) on a THREDDS server hosted at TU Delft. These data can be accessed for anlysis purpose, using the OPeNDAP protocol. The main data catalog is available at: https://africarain.ceg.tudelft.nl:9010/thredds/catalog.html

To work with these files on your local system via OPeNDAP, you first need to obtain an OPeNDAP-enabled client program. Some common client programs include NCO, MATLAB, R, ArcGIS, Python and others. Please see this information page from the NOAA Physical Sciences Library for more information.

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2.2. Access ARP data using Python

This is an example of how to access data from the Africa Rain THREDDS server using Python. This relies on the netCDF4 library, a powerful library for working with netCDF data in general. This example uses a dummy dataset, which endpoint is https://africarain.ceg.tudelft.nl:9010/thredds/dodsC/demos/demo.nc

import netCDF4

# endpoint for specific file

url = 'https://africarain.ceg.tudelft.nl:9010/thredds/dodsC/demos/demo.nc'

# read dataset
nc = netCDF4.Dataset(url)

# read variables
ncv = nc.variables
print(ncv.keys())

## a subset of the data set can be retrieved using coordinate.
## Use relevant coordinates for your dataset, the values below are just an example
# lon = ncv['longitude'][10:-10:2,20:-10:2]
# lat = ncv['latitude'][10:-10:2,20:-10:2]

# read the nth time step
itime = 10
tair = ncv['air_temperature'][itime]

# print data
print(tair)

## Other examples: https://publicwiki.deltares.nl/display/OET/Reading+data+from+OpenDAP+using+python

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2.3. Contact

Processed data will be available directly from the THREDDS URL listed above. Data must be cited appropriately and used in accordance with licensing requirements. See Licensing and citation

Raw data files (see Production of raw data files) are available upon request from Nick van de Giesen, n.c.vandegiesen@tudelft.nl.