PyAPS

PyAPS - Python based Atmospheric Phase Screen estimation

This Python 3 module estimates differential phase delay maps due to the stratified atmosphere for correcting radar interferograms. It is rewritten in Python 3 language from PyAPS source code and adapted for ECMWF’s ERA-5 corrections.

WARNING: The current version does not work with NARR and MERRA datasets. Contributions are welcomed.

This is research code provided to you “as is” with NO WARRANTIES OF CORRECTNESS. Use at your own risk.

1. Installation

a. Install the released version [recommended]

pyaps3 is available on the conda-forge channel, PyPI and the main archive of the Debian GNU/Linux OS. The released version can be installed via conda as:

conda install -c conda-forge pyaps3

or via pip as:

pip install pyaps3

or via apt (or other package managers) for Debian-derivative OS users, including Ubuntu, as:

apt install python3-pyaps3

b. Install the development version

pip install git+https://github.com/insarlab/PyAPS.git

git clone https://github.com/insarlab/PyAPS.git
conda install -c conda-forge --file PyAPS/requirements.txt --file PyAPS/tests/requirements.txt
python -m pip install -e PyAPS

python PyAPS/tests/test_calc.py

2. Account setup for ERA5

ERA5 data set is redistributed over the Copernicus Climate Data Store (CDS). Registration is required for the data access and downloading.

• Create a new account on the CDS website if you don’t own a user account yet. Note: the old CDS account won’t work (Goodbye legacy CDS, Hellow New CDS!).
• CDS API setup: Create the local file $HOME/.cdsapirc (in your Unix/Linux environment) and add the following two lines:

url: https://cds.climate.copernicus.eu/api
key: your-personal-access-token

Your Personal Access Token can be found under Your profile > Personal Access Token section or on the setup guide page. Alternatively, you could add the token to the [CDS] section in model.cfg file in the package directory, site-packages/pyaps3 if installed via conda. Note: using your legacy CDS API key will lead to a 401 Client Error and Authentication failed.

• Make sure that you accept the data license in the Terms of use on ECMWF website: Login, under Datasets > ERA5 hourly data on pressure levels from 1940 to present > Download > Terms of use, click Accept to accespt the license to use Copernicus Products.

• Test the account setup by running:

git clone https://github.com/insarlab/PyAPS.git --depth 1
python PyAPS/tests/test_dload.py

3. Citing this work

The methodology and validation can be found in:

• Jolivet, R., R. Grandin, C. Lasserre, M.-P. Doin and G. Peltzer (2011), Systematic InSAR tropospheric phase delay corrections from global meteorological reanalysis data, Geophys. Res. Lett., 38, L17311, doi:10.1029/2011GL048757.