read_grib order of data

Hi, we are working with surface pressure data from ECMWF:s ERA-Interim. We know how to extract GRIB-files using read_grib. What we know is that the data is in the fltarray and that we can access it by writting grib_struct.fltarray. In doing this we get a list of data. The problem is that we have 88,838 values, one for each grid point, but we don't know how to see which value corresponds to which grid point. We know that La1 is 89.4630, Lo1 is 0, La2 is -89.4630 and Lo2 is 359.2970. We only need to know which grid points that correspond to the Northern Hemisphere and the Southern Hemisphere, respectively. Is it safe to assume that the first half of the data corresponds to the Northern Hemisphere and that the rest correspond to the Southern Hemisphere?

We hope for help as soon as possible since this is for our Bachelor project in Meteorology.

Best regards, Andy and Emy

Answer 1

[K E]

While it is too late for your project, I will mention the wgrib2 package, which you could run from the Matlab command line using the ! character as shown below. If you want to list out the lat/lon grid of a grib2 file called multi_1.glo_30m.hs.200502.grb2, all you need to do is use the -grid option:

!"C:\Program Files (x86)\wgrib\wgrib2.exe" multi_1.glo_30m.hs.200502.grb2 -grid

On my windows machine I had to put the full path to the wgrib2 executable which is in the quotes, but your implementation may not need that. There are many other things you can do with wgrib2. If you just type the following you will list them all.

!"C:\Program Files (x86)\wgrib\wgrib2.exe"