Changes between Version 30 and Version 31 of HYCOM
- Timestamp:
- 10/09/09 15:59:22 (1 month ago)
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HYCOM
v30 v31 37 37 At the time of this writing, HYCOM output could be acquired from [http://www.hycom.org] as OPeNDAP datasets in a THREDDS catalog and as series of netCDF files from an FTP or HTTP server. If you are familiar with OPeNDAP and can write the code necessary to acquire data through it, I suggest you use it, particularly if you only need a small subset of the data. 38 38 39 In the project that gave rise to this example, I needed to acquire four years of temperature and currents data for all 33 depth layers. This worked out to be about 9 TB of data. I found that it was faster to download netCDF files than go through OPeNDAP for that much data. Although the HYCOM FTP server appeared to impose a throughput limit of 1.25 MB/s per FTP download, I was able to run 15 simultaneous downloads with SmartFTP and maintain an overall throughput of 20 MB/s. If you have a fast Internet connection, this may a good way to acquire data quickly. The remainder of this example assumes you will also use netCDF files.39 In the project that gave rise to this example, I needed to acquire four years of temperature and currents data for all 33 depth layers. This worked out to be about 9 TB of data. I found that it was faster to download netCDF files than go through OPeNDAP for that much data. Although the HYCOM FTP server appeared to impose a throughput limit of 1.25 MB/s per FTP download, I was able to run 8 simultaneous downloads with SmartFTP and maintain an overall throughput of 10 MB/s. If you have a fast Internet connection, this may a good way to acquire data quickly. The remainder of this example assumes you will also use netCDF files. 40 40 41 41 On the HYCOM FTP server, the directory housing each dataset was organized like this: 95 95 5. Create the directory '''C:\HYCOM\NetCDFs'''. 96 96 97 6. On the HYCOM server, go to the '''data''' directory and then to the subdirectory for your oceanographic variable of interest, either '''salt''', '''temp''', '''u''', or '''v'''. Download the netCDF files ({{{.nc}}} file extension) for your dates of interest. If you are downloading a lot of files and have a fast Internet connection, consider using a program like SmartFTP that can download multiple files simultaneously, to work around the per-file throughput limitation imposed by the server. (I was told by Michael !McDonald of HYCOM that this is ok .)97 6. On the HYCOM server, go to the '''data''' directory and then to the subdirectory for your oceanographic variable of interest, either '''salt''', '''temp''', '''u''', or '''v'''. Download the netCDF files ({{{.nc}}} file extension) for your dates of interest. If you are downloading a lot of files and have a fast Internet connection, consider using a program like SmartFTP that can download multiple files simultaneously, to work around the per-file throughput limitation imposed by the server. (I was told by Michael !McDonald of HYCOM that this is ok, although at the time of this writing the HYCOM server limited number of simultaneous connections from the same client IP address to 8.) 98 98 99 99 7. Create the directory '''C:\HYCOM\Rasters'''.
