swepy 0.0.17

A python package for obtaining and cleaning Tb files

Disclaimer

• Currently this script is not supported in Windows due to pynco only supporting Mac OS or Unix

• Web scrapping currently only working on the northern hemisphere, fix coming soon

• Requires python 3.6 and Anaconda 3

Setup:

Setup Earthdata Login

Create an Earthdata account to be able to download data: https://urs.earthdata.nasa.gov/

Optional (.netrc file vs passing Username and Password):

Setup your username and password in a .netrc file
Run this command in the directory you will be working in

echo "machine urs.earthdata.nasa.gov login <uid> password <password>" >> ~/.netrc
chmod 0600 ~/.netrc

uid is your Earthdata username. Do not include the brackets <>.

https://nsidc.org/support/faq/what-options-are-available-bulk-downloading-data-https-earthdata-login-enabled

2. Setup conda environment from yaml (Optional):

Using the yaml file (.yml) create a new conda environment

conda env create -f swepy_env.yml

3. Install ipykernel (if using jupyter)

source activate swepy_env
python -m ipykernel install --user --name swepy_env --display-name "Python (swepy_env)"

Main Dependencies:

• gdal
• affine
• requests
• scikit-image
• nco (pynco)
• netCDF4
• datetime
• tqdm
• mapboxgl
• pandas

Using SWEpy for analyzing SWE:

1. Import the Library:

from swepy.swepy import swepy

2. Instantiate the class with working directory, date range, bounding coordinates, and earthdata username and password

upper_left = [lat_upleft, lon_upleft]
lower_right = [lat_lowright, lon_lowright]

start = datetime.date(startY, startM, startD)
end = datetime.date(endY, endM, endD)

path = os.getcwd()

swepy = swepy(path, start, end, upper_left, lower_right, username, password)

3. Use desired functionality, either separate or individually:

swepy.scrape()
swepy.subset()
swepy.concatenate()

swepy.concatenate(swepy.subset(swepy.scrape()))

4. Or, use scrape_all to avoid massive file sizes:

swepy.scrape_all()

This limits the number of full-size images on your disk at one time.

Using SWEpy's Web Scraper Alone:

• Note: Web scraper is enabled automatically in the scrape_all workflow, however it can also be used as a stanalone function!

from swepy.nsidcDownloader import nsidcDownloader

## Ways to instantiate nsidcDownloader
nD = nsidcDownloader.nsidcDownloader(username="user", password="pass", folder=".") ## user/pass combo and folder

nD = nsidcDownloader(sensor="SSMIS") ## user/pass combo from .netrc and default folder, setting the default key of sensor

## Download a file:

file = {
    "resolution": "3.125km",
    "platform": "F17",
    "sensor": "SSMIS",
    "date": datetime(2015,10,10),
    "channel": "37H"
}

nD.download_file(**file)

nD.download_range(sensor="SSMIS", date=[datetime(2014,01,01), datetime(2015,01,01)])

• Authentication will work if the user/pass combo is saved in ~/.netrc, or if it is passed in the nsidcDownloader instance

• The class formats the following string:

 "{protocol}://{server}/{datapool}/{dataset}.{version}/{date:%Y.%m.%d}" \
                    "/{dataset}-{projection}_{grid}{resolution}-{platform}_{sensor}" \
                    "-{date:%Y%j}-{channel}-{pass}-{algorithm}-{input}-{dataversion}.nc"

Function Summaries

Descriptions of included functions

get_xy(ll_ul, ll_lr)

• Parameters: lists of latitude/longitude upper left, latitude/longitude lower right
• Uses NSIDC scripts to convert user inputted lat/lon into Ease grid 2.0 coordinates
• Returns: Ease grid 2.0 coordinates of inputted lat/longs

subset(list6, path)

• Parameters: coordinates of area of interest, current working directory
• Subset will get the files from wget directory and subset them geographically
• Returns: subsetted file

concatenate(path, outfile_19, outfile_37, final=False)

• Parameters: current working directory, output file for 19Ghz, output file for 37Ghz
• The concatenate function merges all netCDF files into one large file
• Returns: concatenated netCDF file

file_setup(path)

• Parameters: current working directory
• setup files needed for other functions
• Returns: create correct folders for use by other functions

scrape_all(start, end, list3, path=None)

• Parameters: start date, end date, list, current working directory(optional)
• Complete function that downloads, concatenates, and subsets data
• Returns: file names of concatenated 19/37 time cubes

plot_a_day(file1, file2, path, token)

• Parameters: 19Ghz files, 37Ghz files, current working directory, mapbox token
• Plots a day of data using Mapbox Jupyter
• Returns: interactive map of inputted data

Troubleshooting

1. ‘image not found’ errors If encountering ‘image not found’ errors then one possible fix is to add theconda-forge channel on top of the defaults in your .condarc file. This is a hidden file, show hidden files and then edit the .condarc file and make your file look like this:

   $ cat .condarc channels:

   • conda-forge
   • defaults

After saving this file, update conda:

conda update all

https://conda-forge.org/docs/conda-forge_gotchas.html#using-multiple-channels

2. HDF5 errors: If getting HDF5 errors, try deleting all the netCDF files in your directories.