Problem with Rsoftware and file OpenDap

Open-source Project for a Network Data Access Protocol

Problem with Rsoftware and file OpenDap

Postby alexandremodi » Thu Feb 28, 2019 3:01 am

Hello everyone, :D

I'm trying to download many files with OpenDap in R software but I have a problem ...
Indeed, I want to download all files of GHRSST Level 4 MUR Global Foundation Sea Surface Temperature Analysis (v4.1)from 2002 to 2018 because I need to get the sea ice fraction.

But I just need these data on a specific grid so I would like to create a loop to download all files with some constraints of variables and latitude / longitude .
In the order to do this, I have got the URL for (an example) the 2019 september 20th :
https://podaac-opendap.jpl.nasa.gov:443 ... .1.nc?time[0:1:0],lat[2000:1:4000],lon[18000:1:27000],sea_ice_fraction[0:1:0][2000:1:4000][18000:1:27000]"

When I try download this URL directly by the R software (function download.file), I have the whole of this file, all variables on the whole of the Earth so it's a great problem because each file make 330 Mo ...

My function in R studio is :
download.file("https://podaac-opendap.jpl.nasa.gov:443/opendap/allData/ghrsst/data/GDS2/L4/GLOB/JPL/MUR/v4.1/2017/263/20170920090000-JPL-L4_GHRSST-SSTfnd-MUR-GLOB-v02.0-fv04.1.nc?time[0:1:0],lat[2000:1:4000],lon[18000:1:27000],sea_ice_fraction[0:1:0][2000:1:4000][18000:1:27000]",
"nc_20110910090000.nc.nc4",mode="wb")
I hope you can assist me ...

Kind regards,

Alexandre Modi
alexandremodi
 
Posts: 3
Joined: Thu Feb 28, 2019 2:51 am

Re: Problem with Rsoftware and file OpenDap

Postby alexandremodi » Thu Feb 28, 2019 3:10 am

My apologies but I maked a mistkae :
The adresse is : https://podaac-opendap.jpl.nasa.gov:443 ... .1.nc?time[0:1:0],lat[2000:1:4000],lon[18000:1:27000],sea_ice_fraction[0:1:0][2000:1:4000][18000:1:27000]

Kind regards,

Alexandre Modi
alexandremodi
 
Posts: 3
Joined: Thu Feb 28, 2019 2:51 am

Re: Problem with Rsoftware and file OpenDap

Postby yiboj » Mon Mar 11, 2019 8:20 am

Hi Alexandre,

Thanks for the inquiry.
The best way to download Level 3/4 files such as MUR dataset is by using the python subsetting script which is posted in PODAAC Forum by following the link:

viewtopic.php?f=85&t=219

Hope this helps.

Regards,

PODAAC DE
yiboj
 
Posts: 79
Joined: Mon Mar 30, 2015 11:22 am

Re: Problem with Rsoftware and file OpenDap

Postby alexandremodi » Tue Mar 12, 2019 2:44 am

Hi yiboj,

Thank you for your answer.

Finally, with the help of support, I managed to download data in the adress that you've mentioned.

Kind regards,

Alexandre
alexandremodi
 
Posts: 3
Joined: Thu Feb 28, 2019 2:51 am


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