Level-1 Pre-Processor (l1preproc)

The Level-1 Pre-Processor (l1preproc) scripts provides command-line access for pysiral functionality to generate pre-processed Level-1 data required for the geophysical retrieval of sea ice thickness from radar altimeter data in the Level-2 processor.

Required input is the id oder file location of the Level-1 pre-processor definition, the selected time period, and the specific input data version since the processor definition may be applicable to multiple input data versions.

Usage

The Level-1 Pre-Processor can be executed via python or via the command-line interface.

python -m pysiral.scripts l1preproc --help

or

pysiral(.exe) l1preproc --help

Output

    usage: pysiral l1preproc [-h] [-E <month number> [<month number> ...]] [-H nh|sh|global]
                        [-p <platform_id>] [-s <source_dataset_id>]
                        [--multiprocessing | --no-multiprocessing] [-m <num_cores>]
                        <id|filepath> <processing period>

The Level-1 Pre-Processor (l1preproc) is used to generate Level-1 files (l1p) from individual
source radar altimeter files for a given period. Processing steps include the harmonization of
data formats from various radar altimeter missions, the generation of continuous trajectories
over the polar oceans, ingesting auxiliary data and the pre-computation of waveform shape
parameters. Basis for the Level-1 Pre-Processor is a Level-1 Processor Definition file that
defines the the radar altimeter input and processing parameters. The output is a set of Level-1
files (l1p) that contain the harmonized data from the source files, which can be used for
further processing in the Level-2 processor (l2proc).

positional arguments:
    <id|filepath>       Identifier or file path to the Level-1 Pre-Processor definition file.
                        This file contains the settings for the Level-1 processor. The default
                        location for these files is `{pysiral-cfg-location}/proc/l1/`. The
                        identifier is the filename without the `.yaml` extension.
                        E.g.`cryosat2_pds_ipf1e_v1p2` will be resolved to `{pysiral-cfg-
                        location}/proc/l1/cryosat2_pds_ipf1e_v1p2.yaml`.
    <processing period>
                        Period definition for processing, given as a string in the format "YYYY-
                        MM[-DD][:YYYY-MM[-DD]]". If only one date is given, it will be
                        interpreted as a period (e.g., "2023-01" for January 2023 and
                        ("2023-01-01" for one day). If two colon-separated dates are given, they
                        will be interpreted as a start and end date or month.

options:
    -h, --help          show this help message and exit
    -E <month number> [<month number> ...], --exclude-months <month number> [<month number> ...]
                        List of months to be excluded from processing, given as integers (1-12).
    -H nh|sh|global, --hemisphere nh|sh|global
                        Target hemisphere for processing. Options are 'global', 'nh', or 'sh'.
                        The latitude limit of the hemisphere is defined in the Level-1 pre-
                        processor settings file. If 'global' is selected, the processor will run
                        for both hemispheres, but still within the latitude limits.
    -p <platform_id>, --platform-id <platform_id>
                        Radar altimeter platform id as defined in pysiral (see `pysiral info
                        --platforms`). This option is required only if the processor
                        configuration file is applicable to multiple platforms (e.g. sentinel3a,
                        sentinel3b, etc.). If the processor configuration file is platform-
                        specific, this option has no effect.
    -s <source_dataset_id>, --source-dataset-id <source_dataset_id>
                        Identifier of the source dataset to be used for processing, summarizing
                        the platform, version, and timeliness information. The source dataset ID
                        must be specified in the local machine definition file ({pysiral-cfg-
                        location}/local_machine_def.yaml, e.g.
                        `root.l1b_repository.<platform>.<source_dataset_id>`)
    --multiprocessing, --no-multiprocessing
                        Flag to allow disabling multiprocessing. If set, the processor will run
                        in single-threaded mode. Default is True, meaning multiprocessing is
                        enabled. (also see option -m/--multiprocessing-num-cores)
    -m <num_cores>, --multiprocessing-num-cores <num_cores>
                        Set the number of CPU cores to be used for multiprocessing. If not set,
                        the default value (derived from `multiprocessing.cpu_count()`) will be
                        used. NOTE: In some managed environments, the default value is not
                        reliable, which may lead to performance issues. In this case, it is
                        recommended to set this value manually to the known number of available
                        CPU cores.

For more information, see: https://pysiral.readthedocs.io

Tip

Future versions of pysiral will support additional options to list and query specific processor settings and their dependencies via

pysiral info --target l1p-settings