MERRA automatic Access

Last update: Jan. 2018

 

    

    FOR PAY  - Contact us for a quotation

Automatic access to meteorological variables from MERRA-2 (NASA) resource. Even if MERRA-2 is for free via a Web interface, we need to dimension our servers to welcome the large number of automatic requests. A fee is thus applied depending on the number of time series retrieved every day / month. Please  for a quotation and receive your SoDa credentials.

Automatic access with WGET - Automatic access with CURL

Download WGET.EXE

    

 Automatic access with WGET

  1. Download wget.exe in a directory (Windows environment - by default available in Unix)
  2. In the same directory, create a text file and copy-paste in a single line the following instruction to test this permanent access to Carpentras, France:
 

wget -O SoDa_MERRA-2_Carpentras.csv --header="soda-user: guest" --header="soda-passwd: guest" ...
"http://www.soda-is.com/pub/merra2_request.php?geopoint=44.083,5.059&firstday=2017-01-01& ...
lastday=2017-01-31&duration=h
"

  1. Rename the text file with the .bat extension and double click on the .bat file to retrieve the SoDa_MERRA-2_Carpentras.csv output file (Windows environment). Rename the text file with a .sh extension and run it using >my_script.sh in a Unix environment.

  The WGET command in details

Request:
wget -O SoDa_MERRA_output.csv --header="soda-user: your_login" --header="soda-passwd: your_password" ...
"http://server/pub/merra2_request.php?geopoint=latitude,longitude&firstday=yyyy-mm-dd ...

&lastday=yyyy-mm-dd&duration=time_step"

Inputs:

  • your_login and your_password: this access is restricted to registered users, i.e. to users who purchased an automatic access to the data. Please contact us for a quotation or to receive your SoDa automatic access credentials 
  • server: "www.soda-is.com" (main server) or "pro.soda-is.com" (mirror server)
  • latitude and longitude: in degrees, with at least 3 digits after comma, e.g. "geopoint=45.563,7.25"
  • yyyy-mm-dd: the first day and last day of your request, from 1980 up to about a month ago
  • time_step: "15" (minutes), "h" (hourly), "d" (daily), "m" (monthly). Automatic requests with a time step below 10 min are limited to one month, and automatic requests with a time step below one day limited to one year (identical to HelioClim-3 automatic request behavior).

Time reference is Universal Time.

Outputs:

Identical to the output columns received via the MERRA-2 Web interface

  Recommendations - other links

Warning! It is strongly recommended to avoid the launch of parallel requests, using the "&" at the end of each wget request line. This would endanger our system.

More info about:

Top of page

Automatic access using CURL

You can also automatically retrieve MERRA-2 dataset by using the CURL command as follows:

Request (Windows):
curl -f -s -S -F stations=@stations.txt -o output_merra-2_curl.csv --header "soda-user: guest" --header "soda-passwd: guest" http://pro.soda-is.com/pub/merra2_request.php

With the following stations.txt file format:
# Columns:
# id: station name
# latitude and longitude: in degrees, with at least 3 digits after comma
# elevation: ignored
# time reference: ignored
# duration: "15" (minutes), "h" (hourly), "d" (daily) or "m" (monthly)
# firstday and lastday: first and the last days of the request, expressed as yyyy-mm-dd
# slope of panel: ignored
# azimuth of panel: ignored
# ground_albedo: ignored
# horizon: ignored (optional)
# calibration: ignored (optional)
# format: ignored (optional)
#
#id         lat    lon   elevation time duration firstday   lastday    slope azimuth albedo
Carpentras1 44.083 5.059 -999      UT   d        1985-01-01 1985-01-31 0     0       0.2
Carpentras2 44.083 5.059 -999      UT   h        1985-01-01 1985-01-05 0     0       0.2

NB: stations.txt is voluntarily identical to the one used to automatically retrieve satellite-derived solar radiation datasets HelioClim-3. Of course, a few parameters are not used to run MERRA-2 but are needed for the CURL request.

Please note that curl output does not contain headers.

Top of page