Program to download and extract grib2 files






















The first line should point to your perl interpreter. The second line needs to point to the location of curl if it is not on your path. Usage: Windows There have been some reports that the perl scripts didn't work on Windows machines. The problem was solved by Alexander Ryan. Hi Wesley, thought this might be of some use to your win32 users.

No matching grib fields. My computer is P4 1. Linux users probably will gravitate towards the cygwin system because it includes bash, an X-server, compilers and the usual unix tools. Of course, egrep understands regular expressions which is a very powerful feature. If you are doing multiple downloads from the same file, you can save time by keeping a local copy of the inventory. A user was complaining about bad downloads.

Turns out that the user was using a modem and cURL was "timing out". The options tell curl to only "time out" when the download rate is less than 30 bytes per second for 30 seconds.

Glad I don't have to use a modem. Notes for Data Providers The grib data needs to accessable be on an http server. Often this is a minor change in the httpd configuration. The users will need a wgrib inventory grib-1 or a wgrib2 inventory grib It is convenient if the inventory is in the same directory as the data files and uses the '. Grib-2 has been supported since the summer of Notes In theory, curl allows random access to FTP servers but in practice we found this to be slow each random access is its own FTP session.

Site Map. CPC Search. Partial http transfers. If You are Lucky, it is Simple. The http protocol allows "random access" reading; however, that means that we need an index file and a http program that supports random access. Warning: Metacharacters. Sample Script. This kitchen miracle was done by a more developer friendly design and the contributions of many people. Some functionality include,. OpenMP is used to speed up wgrib2 by running loops over multiple cores.

With gcc, clang and icc, OpenMP is on by default. In general, you set the number of threads to be less or equal to the number of CPU cores available. Setting the number of threads to 4 leads to a sluggish machine. So I added these two lines to my. Use the clock cycles spent waiting for reading the DRAM. However, more threads means the effective size of the cache per active thread is reduced which means more reading of the DRAM.

So the optimal number of cores is determined by the equivalent of the the Laffer curve for the number of threads. After you download hdf Then you may be able to compile wgrib2 with netCDF4 support by changing the makefile. If you are willing to trust a long-term archive to a format that has only one implementation, well that is your choice.

There are many other programs that can handle grib and NetCDF4. Use one of those programs if you want support. Seg-faults are pretty uncommon to wgrib2. The jpeg library Jasper could seg-fault with larger grids. If your copy of wgrib2 is using another version of the Jasper library, then your copy of wgrib2 may be vunerable to this problem.

Wgrib2 can decode grib using g2clib. Using the g2clib that was not included with the wgrib2 source code could cause a seg-fault. Wgrib2 had patches to g2clib that were not fully incorporated until g2clib v1. In addition, g2clib can be compiled either with a 32 or bit interface. The default makefile assumes that a bit interface is used on bit processors and a bit interface is used bit processors. Third-parties often followed NCEP's lead and used a bit interface for 32 and 64 bit machines.

Finally, the third problem is a compiler bug and only affects wgrib2 v2. The problem is fixed by gcc 2. There a potential for seg-faults by reading using specially crafted png or jpeg compressed grib files.

For example, a few days after the release of wgrib2 v2. Fix has been tested. The default Jasper library produces empty data. This is show that I have some empathy for users with restrictive sys admins. Changes for wgrib2 v3. Bug reports are important Contact wesley. With wgrib2 v3. Scripts that used the older IF structure still work; however, the new IF structure is easier to read.

If possible, it is better to use the match options than the if options. Individual Grid Point Data -ij print value at grid point i, j -ijlat print lat, lon, value at grid point i, j -ilat print lat, lon, value of Nth grid point -lon prints the lat-lon, and value of the grid point nearest the specified lat-lon -max prints the maximum value -min prints the minimum value -stats prints some statistics about the fields -V verbose inventory shows stats Regridding, Interpolating to new grids Wgrib2 has the ability to convert grib files from one grid to another.

The conversion uses a user-selected interpolation scheme: bilinear default , bicubic, nearest neighbor, budget, and spectral. The supported grids include lat-lon, gaussian, Lambert conformal, polar stereographic, and WMO-defined rotated lat-lon grid. Note: the interpolation uses scalar and vector interpolation schemes. For the vector quantities the V field must immediately follow the corresponding U field. You have a sample grib2 message template , and you modify the grid point values and metadata to create a new grib message that you can write.

The other approach is to supply many parameters to create a grib message which is used by NCEP's g2 library. This is a mandatory compile option for some distributions and is just a good idea. However, the gcc in RH5 doesn't support this option. Ubuntu For other systems, you may have to modify the makefile. The makefile requires gnu make is a common version of make.

There has been a debate about moving the base level to C



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