Partial examples of the code used to verify the Level-1B ("ATL02") data products of the NASA science satellite ICESat-2's ATLAS laser altimeter. This includes indepenedent calculations of photon times of flight, radiometry, and housekeeping data conversions.

1. Activate your Python 3 conda environment.

2. Cd to the location you wish to store the package.

3. Type the following

   git clone [email protected]:cgosmeyer/I2L1Bv.git
   

4. Cd to atl02v.

5. Run setup.py to install the package.

   python setup.py develop
   

   You should now be able to import atl02v from anywhere, as long as you are in the same conda environment.

6. Run init_paths.py to generate the output directory structure.

   python init_paths.py
   

   You should now see, in the path you specified, a directory structure as follows

   verification/
       data/
       docs/
       outputs/
           data/
           reports/
           vfiles/
   

   It is your responsibility to add sub-directories to data/ containing each associated batch of ATl01, ATL02, and calibration files that you wish to verify. The outputs/data sub-directory will fill with the h5 and pickle files generated to compare against the ATL02 and the outputs/reports sub-directory will hold any plots or text files created with verification testing. You will also find a new file, atl02v/shared/paths.py containing the paths to outputs you specified. Do NOT git commit this file (it's already listed in the .gitignore, so you should never need think about it).

7. Unzip data/ITOS_db.zip. You will find the files necessary to perform the counts to physical units conversions in atl02v/tof/tof.py, atl02v/radiometry/radiometry.py, vfiles/verify_ancillary_data.py, and vfiles/verify_lrs.py. You can point your "path_to_itos" parameter in atl02v/shared/paths.py here, or move the files.

   WARNING: Do NOT commit the unzipped ITOS_db. It is included in the repo for your convenience. Committing it unzipped will add 40 Mb to the repo, which though easy to fix, will make you and @cgosmeyer temporarily unhappy.

8. If you find a dependency is missing, install it by conda or by pip. (If it is missing from conda, it will be available from pip.)

   conda install missing_package
   

   or

   pip install missing_package
   

The following commands assume you are running the generation and verification scripts from the primary level of atl02v.

Follow these steps to generate the test file one at a time. Once you have a good grasp of what each step is doing, you can instead run the wrapper script gscripts/gen_all.py that will take care of steps 2-7.

1. Place ATL01, ATL02, ANC13, ANC27, and CAL files in a subfolder (preferably named after the granule, e.g., 20190501072836_05040313_203_01) in the verification/data folder.

2. Create a verification file in verification/outputs/vfiles, using as a template examples/vfile_example.csv. Fill in the ATL01 and ATL02 fields, and fill in the rest of the fields as you proceed with the following steps. A single verification file should list only outputs generated under same conditions, for same source ATL01 file, under same version of the software.

3. Generate a photonid hdf5 file (creates map of the ATL02 photons to ATL01).

   python> gscripts/gen_photonid.py
   

4. Generate a Time of Day pickle file.

   python> gscripts/gen_tod.py
   

5. Generate a Time of Flight pickle file.

   python> gscripts/gen_tof.py
   

   WARNING: This is the most time- and memory-intensive script. If you have a large ATL01, you may want to limit the number of majorframes and do the file in chunks; otherwise, the output may be too large to be pickled. See the docstrings of gscripts/gen_tof.py and atl02v/tof/tof.py for more information.

6. Generate a Radiometry pickle file.

   python> gscripts/gen_radiometry.py
   

7. Generate a duplicate mask (marks on a '1' matrix as '0' all ATL01 indices not present in ATL02).

   python gscrips/gen_duplicatemask.py
   

8. Make sure your verification file is completely filled in. You are now ready to start verifying ATL02!

Each higher level group in ALT02 will have its own verification script. The following examples assume you wish to run them one at a time. You can also run all of the verification scripts together using the wrapper vscripts/verify_all.py.

The ATL02 groups to be verified by their own scripts are

ancillary_data
atlas
    housekeeping
    pcex
    tx_pulse_width
gpsr
lrs
orbit_info
sc

In addition, delta_time fields, which are present in every group, has its own verification script, vscripts/verify_delta_time.py

1. EXAMPLE: I want to verify the fields in the atlas/pcex/altimetry group with verification file 11-11-2018.csv

   python> vscripts/atlas_pcex_verification.py --f altimetry --v 11-11-2018.csv
   

2. EXAMPLE: I want to verify in one go the fields in all subgroups of atlas/pcex/ with verification file 11-11-2018.csv

   python> vscripts/atlas_pcex_verification.py --v 11-11-2018.csv
   

3. EXAMPLE: I want to verify the fields in both the atlas/pcex/altimetry and atlas/pcex/tep groups in one go with verification file 11-11-2018.csv

   python> vscripts/atlas_pcex_verification.py --f altimetry tep --v 11-11-2018.csv
   

For all examples, check outputs/reports for a directory named for the ATL01 basefile (e.g., 20190501072836_05040313_203_01), and in that directory, a time-stamped directory specific to each run of the verification scripts. These time-stamped directories will contain the following:

• Field-specific verification reports. For example, ancillary_data.atlas_sdp_gps_epoch.csv
• Field-specific diff plots. For example, ancillary_data.atlas_sdp_gps_epoch.png
• Record of ATL01, ATL02, and pickle files used in the run of the software, vfiles.csv
• Abridged summary of all the verification reports in the group, vsummary.csv
• Plotted pass/fail and completed/errored summary of all verification reports in the group, vsummary.png

If the group under verification contains fields that were converted from counts in ATL01 to physical units in ATL02, the conversion expressions will be recorded in a summary file. For example, in the group "atlas/housekeeping/meb" a report will be generated named meb.csv.