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IceFlow wiki

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Google Drive

Original project page

What do we call it?

IceFlow, gmbflow, GMBflow

Overall idea

Develop a workflow to derive glacier mass balance from a set of remote-sensing derived DEMs.

Steps for Development##

0. Set up and organize repository - David & David

   • Research and add better notes for properly working with submodules

1. Research and develop tools to download freely available data (SRTM, ASTER, landcover, ...) - Iliyana, David S

   • Identify a good set of sample DEMs to use for development
   • Explore recent release of elevation for [SRTM] (http://www2.jpl.nasa.gov/srtm/) download
   • Sample script to get latest RGI glacier polygons: demcoreg/get_glacier_poly.sh
   • Individual [ASTER14DEM 30 m products] (https://lpdaac.usgs.gov/dataset_discovery/aster/aster_products_table/ast14dem_v003) used for GDEM should now be publicly available

2. Raster clipping, resampling... - Ellie, Jessica, Amaury

   • see pygeotools/warptool.py and pygeotools/lib/warplib.py

3. DEM co-registration DONE - Ellie, Salvatore

   • Need mask of exposed rock surfaces for each input DEM, see demcoreg/dem_mask.py skipping this to save time.

   • Run ASP's pc_align (see Section A.17 of Official ASP documentation

   • OR run one of the functions in demcoreg/coreglib.py to determine appropriate translation

   • Compute elevation difference stats before and after co-registration

   • (1) run glacierhack_WV_coreg_all.sh in the folder with the un corrected DEMS

   • (2) run glacier hack_32_translate.sh in the folder with the corrected DEMS

4. Elevation change difference/trends - Salvatore, Amaury

   • For two input DEMs, see demcoreg/compute_dz.py and demcoreg/robust_stats.py
   • For n input DEMs and generating a time series "stack", see pygeotools/make_stack.py
     • Alternatively, take a look at iceflow/regression.py for a numpy/pygeoprocessing-based implementation.
   • Also consider xarray/dask after nDarray tutorials

5. Interpolation, filtering, and gap filling - Salvatore, Iliyana, Jessica

   • David S will dig up some existings Python scripts for filling nodata using several methods (GDAL, inpainting)

   • See [iceflow/dem_fill.py]

   • See [pygeotools/lib/filtlib.py] - some filters

   • Do latest versions of OpenCV inpainting support Float32 inputs?

   • Continuous space-time?

     • Create DEMStack from arbitrary list of DEM inputs using make_stack.py
     • Run ndinterp.py with an input mask defining desired spatial extent for interpolation (or comment out for full stack extent)
     • Currently stuck with hardcoded values for desired output timestamp, etc.

6. Density assumptions/model (combine with 7?)

7. Compute mass change - Amaury, David L.

   • David S added vol_stats.py for reference and quick analysis
   • Assumes constant density for ice and prints stats of total volume change for unmasked pixels

8. Documentation/packaging - All

Git beginners project

Create a set of tools to read and display rasters and vectors, preferably using Python classes:

• read/save rasters using GDAL - see georaster/georaster.py and the GeoHackWeek course

• display the raster with coordinates, with different colorbar options (e.g. grey level for Byte type, RdBu for positive/negative values, viridis for only one sign...) using matplotlib/basemap - see visualization tools

• read RGI outlines and display - see geoutils/geovector.py and GeoHackWeek course that uses GeoPanda

• create a quick raster/vector visualization tool that can be run from command-line using argparse - see pygeotools/pygeotools/warptool.py and argparse website

Workflow

The workflow is composed of a set of 5 independent scripts, detailed below.

1. Original DEMs => || warptool.py || => warped DEMs

2. warped DEMs + RGI mask + landcover => || demcoreg.py || => coregistered DEMs

3. coregistered DEMs => || elevation_change.py || => dhdt

4. dhdt => || gap_filling.py || => filled dhdt

5. filled dhdt + RGI outlines => || mass_balance.py || => individual glacier MB

We will work with the 32 m WV DEMs. Two that have similar geographic coverage (and align with the ASTER DEMs) are: WV01_20141022 and WV01_20150607, both in the Khumbu_ASP directory.

In order for the scripts to interact, we need to agree on some specifications:

• format: the common format is GeoTIFF

• no data value: store the GTiff with no data value = -9999

• filename: the individuals DEMs will have a prefix to identify the DEM source (e.g. WV_, ASTER_...), the acquisition date written in the format YYYYMMDD, followed by a suffix depending on the processing step: ID_YYYYMMDD_warped.TIF , ID_YYYYMMDD_coreg.TIF...

Data

We will start with the WV DEMs provided by David Shean. They cover 2 regions, we will start with the Ngozumpa glacier. The DEMs at 32 m resolution are all in the data/WV_Ngozumpa folder on the Google drive.

Later, we can try to apply the processing chain to WV_Everest and to the ASTER DEMs.

Developers

Amaury Dehecq (adehecq)

David Shean (dshean)

David Lilien (dlilien)

Salvatore G. Candela (scandelaOSU)

Ellie Bash (ellie-b)

Jessica Scheick (JessicaS11)

Iliyana Dobreva ([iliyanadobreva] (https://github.com/iliyanadobreva))

Notes