'Fix' offset and undersized data in QGIS

Question

I'm currently working on a project to visualize some climate data, among the datasets I'm using is the data from the NCEP/NCAR Reanalysis Project.

Now, this data comes in a regular (non-gaussian) grid of a resolution of 144 by 73 and spans longitudes 0° to 357.5° East. This results in qgis displaying the following:

Where the colored data should span the entire globe but instead spans from 0°S to 73°S and from 0°E to 144°E

The data is in NetCDF (.nc) format

How do I go about 'fixing' this data to properly cover the real coordinates? I've tried georeferencing the file but QGIS is unable to write an output file (probably due to the multiple levels of data the file has).

PS: I'm working with the WGS 84 CRS

Answer 1

I don't know which is your especific product but, you can fix it by using the OSGeo Shell, of QGIS suite, with the gdal_translate command. I downloaded this *.nc file from your link:

air.sig995.1948.nc

to try out my approach. It looks in QGIS as in the below image:

The Spatial Coverage is:

2.5 degree latitude x 2.5 degree longitude global grid (144x73)
90N - 90S, 0E - 357.5E

For this reason, the complete gdal_translate command to use in the OSGeo shell it would be (output file could be a GTiff raster; air.sig995.1948_proj.tif):

gdal_translate -a_srs WGS84 -a_ullr 0 90 357.5 -90 air.sig995.1948.nc air.sig995.1948_proj.nc

After running the gdal_translate command, it was corroborated that the image had the correct Spatial Coverage. Please, adapt for your particular use.