Code and data for: Snow Water Equivalent Change Mapping from Slope Correlated InSAR Phase Variations

This repository contains the scripts used to implement Snow Water Equivalent (SWE) mapping from repeat pass InSAR phase
maps based on spatial correlation of dry-snow refractive phase and topographic slope.

This code was used to produce all results and figures for the paper submitted to The Cryosphere Disscusions:
the paper submitted to The Cryosphere Disscus:
[Eppler, et al,. accepted for publication](https://doi.org/10.5194/tc-2021-359)

This repository also contains in situ snow survey transect data consisting of series of snow depths and snow tube
derived SWE measurements made by the authors and referenced in the paper.

The content of the repository is the following:

**I. data analysis and plotting code**
The main entry point to the code is the script (jeppler_slope_correlated_swe_paper.py).  It contains functions to
estimate SWE and corresponding estimation variance maps from a set of input interferograms and DEM. It also contains a
number of analysis functions used to generate the tables and figure included in the paper.

**Input data**
* The input data to run all the scripts includes RADARSAT-2 imagery and a TerraSAR-X DEM. These are disctributed under a
 restricted user license and cannot be redistributed.
* Snow Survey transect data.  The authors' datasets have been included (snow_survey_measurements.py).
* ECMWF ERA5 and Environment and Climate Change Canada (ECCC) csv format data files.  These are publicly available from
 ECMWF and ECCC respectively.

**Output data**
* The main script (jeppler_slope_correlated_swe_paper.py) generates a series of figures that we included in the paper.

## External softare libraries that are not in the included environment:
The code requires the GAMMA InSAR processing software which is commercial software available from
Gamma Remote Sensing AG (www.gamma-rs.ch).

The code also requires python modules developed by the Simon Fraser University (SFU) SARLab that I do not have rights to
 distribute.
Please contact Dr. Bernhard Rabus (btrabus@sfu.ca) regarding access to these additional modules.  Note that these are
utility modules and do not contain any of the method details described in the submitted manuscript.
Specifcally this include:
sarlab.tools.conversion: geodetic coordinate system transformation
sarlab.gammax: custom interface code for the GAMMA software
sarlab.multiprocess_gx: multiprocessing pool customization
sarlab.tools: least squares polynomial fitting and png image format rendering
sarlab.met.env_canada: parsing of ECCC csv format data files