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Describes the programs and procedures to calculate elevation change rates from Level-2 Operation IceBridge Land, Vegetation and Ice Sensor (LVIS) data.
Acquire IceBridge LVIS data:
https://github.com/tsutterley/nsidc-earthdata
IceBridge Flight Summaries:
https://nsidc.org/data/icebridge/campaign_data_summary.html
https://nsidc.org/data/ILVIS2
https://nsidc.org/data/ILVGH2
https://lvis.gsfc.nasa.gov/Data/DataStructure.html
Level-2 elevation datasets from NSIDC. The datasets are tab-delimited ascii and can be very large. Some releases of the data were stored in a big-endian binary format (all reprocessed in 2014). LVIS geolocated Level-2 data are calculated from the full-waveform Level-1 product.
https://lvis.gsfc.nasa.gov/Data/Data_Structure/DataStructure_LDS104.html
Level-2 data supplies 3 different elevation surfaces: lowest and highest return from Gaussian decomposition and the centroid surface (surface of equivalent volume within footprint).
| Variable | Description |
|---|---|
| LVIS_LFID | LVIS file identification |
| Shot_Number | Laser shot assigned during collection |
| Time | UTC decimal seconds of the day |
| Longitude_Centroid | Centroid longitude from corresponding Level-1B waveform |
| Latitude_Centroid | Centroid latitude from corresponding Level-1B waveform |
| Elevation_Centroid | Centroid elevation from corresponding Level-1B waveform |
| Longitude_Low | Longitude of the lowest detected mode within the waveform |
| Latitude_Low | Latitude of the lowest detected mode within the waveform |
| Elevation_Low | Elevation of the lowest detected mode within the waveform |
| Longitude_High | Longitude of the highest detected mode in the waveform |
| Latitude_High | Latitude of the highest detected mode in the waveform |
| Elevation_High | Elevation of the highest detected mode in the waveform |
https://lvis.gsfc.nasa.gov/Data/Data_Structure/DataStructure_LDS202.html
Level-2 data supplies 3 different elevation surfaces: lowest and highest return from Gaussian decomposition and the highest detected signal within the waveform. In addition, relative heights for different percentages of the total waveform energy are provided in meters above the lowest detected mode.
| Variable | Description |
|---|---|
| LFID | LVIS File Identification |
| shotnumber | Laser shot number assigned during collection |
| time | UTC decimal seconds of the day |
| glon | Longitude of the lowest detected mode within the waveform |
| glat | Latitude of the lowest detected mode within the waveform |
| zg | Mean elevation of the lowest detected mode within the waveform |
| tlon | Longitude of the highest detected signal |
| tlat | Latitude of the highest detected signal |
| zt | Elevation of the highest detected signal |
| hlon | Longitude of the center of the highest mode within the waveform |
| hlat | Latitude of the center of the highest mode within the waveform |
| zh | Mean elevation of the highest mode within the waveform |
| RH10 | Height above zg at which 10% of the waveform energy occurs |
| RH15 | Height above zg at which 15% of the waveform energy occurs |
| RH20 | Height above zg at which 20% of the waveform energy occurs |
| RH25 | Height above zg at which 25% of the waveform energy occurs |
| RH30 | Height above zg at which 30% of the waveform energy occurs |
| RH35 | Height above zg at which 35% of the waveform energy occurs |
| RH40 | Height above zg at which 40% of the waveform energy occurs |
| RH45 | Height above zg at which 45% of the waveform energy occurs |
| RH50 | Height above zg at which 50% of the waveform energy occurs |
| RH55 | Height above zg at which 55% of the waveform energy occurs |
| RH60 | Height above zg at which 60% of the waveform energy occurs |
| RH65 | Height above zg at which 65% of the waveform energy occurs |
| RH70 | Height above zg at which 70% of the waveform energy occurs |
| RH75 | Height above zg at which 75% of the waveform energy occurs |
| RH80 | Height above zg at which 80% of the waveform energy occurs |
| RH85 | Height above zg at which 85% of the waveform energy occurs |
| RH90 | Height above zg at which 90% of the waveform energy occurs |
| RH95 | Height above zg at which 95% of the waveform energy occurs |
| RH96 | Height above zg at which 96% of the waveform energy occurs |
| RH97 | Height above zg at which 97% of the waveform energy occurs |
| RH98 | Height above zg at which 98% of the waveform energy occurs |
| RH99 | Height above zg at which 99% of the waveform energy occurs |
| RH100 | Height above zg at which 100% of the waveform energy occurs |
| azimuth | Azimuth angle of the laser beam |
| incidentangle | Off-nadir incident angle of the laser beam |
| range | Distance between the instrument and the ground |
| Complexity | Complexity metric for the return waveform |
| Flag1 | Flag indicating LVIS channel used to locate zg |
| Flag2 | Flag indicating LVIS channel used calculate RH metrics |
| Flag3 | Flag indicating LVIS channel waveform contained in Level1B file |
- Alternative program to convert LVIS Level-2 data from NSIDC directly into HDF5 files.
- Will not download the ascii files locally.
python nsidc_convert_ILVIS2.py --user=<username> --mode=0775 -Y X, --year=X: years to sync separated by commas
-S X, --subdirectory=X: subdirectories to sync separated by commas
-U X, --user=X: username for NASA Earthdata Login
--directory: local working directory
-M X, --mode=X: Local permissions mode of the directories and files synced
-V, --verbose: Verbose output of files synced
-C, --clobber: Overwrite existing data in transfer