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Hi Karnan, You can do that kind of thing with OPeNDAP datasets, but FTP does not work that way. The netCDF library, which Ferret uses to open netCDF and remote urls does not open FTP datasets. A search for "OSCAR data sets opendap jpl" turns up, for
instance, this link:
https://podaac.jpl.nasa.gov/dataset/OSCAR_L4_OC_third-deg. Near
the top of that page is a blue tab called "Data Access", which
shows the different modes of access with some explanations. I chose the second link there, "OPeNDAP". Exploring the
different links from there for available data, I found this page
which shows a big dataset
listing. Click on one of those files, or on the 'html' link
over to the right for a file you want to access. The next you'll
see next gives the "Data URL" and that's what you can put into a
Ferret command: *** NOTE: Axis coordinates are decreasing-ordered. Reversing ordering for axis latitude yes? show data currently SET data sets: 1> https://opendap.jpl.nasa.gov:443/opendap/OceanCirculation/oscar/preview/L4/resource/LAS/oscar_third_deg_180/oscar_vel1992_180.nc (default) name title I J K L U Ocean Surface Zonal Currents 1:1081 1:481 1:1 1:14 V Ocean Surface Meridional Curren 1:1081 1:481 1:1 1:14 UM Ocean Surface Zonal Currents Ma 1:1081 1:481 1:1 1:14 VM Ocean Surface Meridional Curren 1:1081 1:481 1:1 1:14 yes? shade/l=3 u ! quick look at the data yes? show grid u GRID GAS1 name axis # pts start end subset LONGITUDE LONGITUDE 1081 r 180E(-180) 180E full LATITUDE LATITUDE 481 r 80S 80N full DEPTH DEPTH (m) 1 r- 15 15 full TIME TIME 14 r 21-OCT-1992 20:00 26-DEC-1992 21:59 full Just one more hint here. Note that the longitude is not a modulo access (if it were the SHOW GRID would show 1081mr with an "m" under # pts). If you wanted to save, say a set that spans the Pacific Ocean, you could tell Ferret to treat that axis as a modulo axis yes? set axis/modulo `u,return=xaxis` !-> set axis/modulo LONGITUDE yes? show grid u GRID GAS1 name axis # pts start end subset LONGITUDE LONGITUDE 1081mr 180E(-180) 180E full LATITUDE LATITUDE 481 r 80S 80N full DEPTH DEPTH (m) 1 r- 15 15 full TIME TIME 14 r 21-OCT-1992 20:00 26-DEC-1992 21:59 full yes? save/x=150:190/y=-2:12/file=mysubset.nc u,v On 12/21/2017 11:16 PM, Karnan C wrote:
Dear ferret users, I would like to download the OSCAR data sets directly from the web servers through ferret. If I do that, I can set my area of interest and store a small size data in my computer, rather than downloading ~500mb data set. I can't succeed do obtain the data. 1). It was FTP server and when I tried, I got error. Data: oscar_vel1992_180.nc Server: ftp://podaac-ftp.jpl.nasa.gov/allData/oscar/preview/L4/resource/LAS/oscar_third_deg_180/ use "ftp://podaac-ftp.jpl.nasa.gov/allData/oscar/preview/L4/resource/LAS/oscar_third_deg_180/oscar_vel1992_180.nc" **netCDF error No such file or directory (OPeNDAP/netCDF Error code 2) Data set: ftp://podaac-ftp.jpl.nasa.gov/allData/oscar/preview/L4/resource/LAS/oscar_third_deg_180/oscar_vel1992_180.nc 2). Some of the online data sets were zipped in the FTP server. Data: oscar_vel1992.nc.gz Server: ftp://podaac-ftp.jpl.nasa.gov/allData/oscar/preview/L4/oscar_third_deg/ Please share some ideas to do it successfully. Thank you. |