How to download daily data to your personal computer from NASA PODAAC

1) Register for an account with Earthdata Login here:

https://urs.earthdata.nasa.gov/oauth/authorize?client_id=HrBaq4rVeFgp2aOo6PoUxA&redirect_uri=https%3A%2F%2Farchive.podaac.earthdata.nasa.gov%2Fredirect&response_type=code&state=%2Fs3credentials

make sure you save your username and password you will need them later!

2) Select the dataset you want to use from NASA PODAAC. This example will use the GHRSST dataset

Note the short name of the dataset. For this example it would be "MUR-JPL-L4-GLOB-v4.1"

3) Download the PODAAC data subscriber package using terminal. On a mac:

 pip install podaac-data-subscriber  

4) Create a .netrc file using a text editor in terminal (IE using nano)

 nano ~/.netrc 

5) in the .netrc file replace with your earthdata username and password

 machine urs.earthdata.nasa.gov
login your_earthdata_username
password your_earthdata_password 

6) make sure the file is only readable by you:

chmod 600 ~/.netrc

7) Test if this worked. If you are prompted for a username or password something went wrong

curl -n https://urs.earthdata.nasa.gov

8) Navigate to where you want the data to be downloaded to on your computer (ie using cd ____)

9) Download the files! (you can only download one year of data at a time) This is where you need the short name of the dataset from earlier.

podaac-data-downloader -c shortnameofdataset -d ./data \

  --start-date YYYY-MM-DDT00:00:00Z \

 --end-date YYYY-MM-DDT00:00:00Z \

  -b="-179,-90,180,90" --verbose1
  

with the example dataset and the year 2002 it would be:

  podaac-data-downloader -c MW_IR_OI-REMSS-L4-GLOB-v5.0 -d ./data \
  --start-date 2002-06-01T00:00:00Z \
  --end-date 2002-06-08T00:00:00Z \
  -b="-179,-90,180,90" --verbose

  

repeat step 9 for as many years as you need changing the start and end date

Subsetting the files downloaded to a specific region:

1) Make sure you have NCO installed

using conda: conda install -c conda-forge nco

2) Navigate to the folder where you downloaded your data in terminal

using cd....

2) Create a bash file in the folder where your data is located using a text editor (IE nano on a mac)

using nano: nano yourbashfilename.sh

3) Using your desired bounding box (with start lat/lons and end lat/lons) and subset filenames update this text in the bash file:

#!/bin/bash
# Define the latitude and longitude bounds
lat_min=value
lat_max=value
lon_min=value
lon_max=value

# Loop through the NetCDF files and perform subsetting
for f in *.nc
do
  echo "Processing $f file..."
  # Use value-based subsetting
  ncks -d latitude,$lat_min,$lat_max \
       -d longitude,$lon_min,$lon_max \
       "$f" "updatedfilename_$f"
done

make sure you check what format the lat/lons are in the datafiles! Many of the lat/lons on PODAAC are 0-360 not -180 to 180 format.

For a region in the Carribean using lat/lons with 0-360 this is what the bash file text would be:

#!/bin/bash
# Define the latitude and longitude bounds
lat_min=13.955392
lat_max=16.888660
lon_min=290.105
lon_max=295.356

# Loop through the NetCDF files and perform subsetting
for f in *.nc
do
  echo "Processing $f file..."
  # Use value-based subsetting
  ncks -d latitude,$lat_min,$lat_max \
       -d longitude,$lon_min,$lon_max \
       "$f" "carib_$f"
done

4) run the bash file!

a) make the file executable: chmod +x yourbashfilename.sh b) run the script: ./yourbashfilename.sh

You should have datasets cut to a specific region with the years downloaded from PODAAC!