77 lines
6.4 KiB
Markdown
77 lines
6.4 KiB
Markdown
# Pick-Correlation Correction
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## Introduction
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Currently, the pick-correlation correction algorithm is not accessible from they PyLoT GUI. The main file *pick_correlation_correction.py* is located in the directory *pylot\correlation*.
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The program only works for an obspy dmt database structure.
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The basic workflow of the algorithm is shown in the following diagram. The first step **(1)** is the normal (automatic) picking procedure in PyLoT. Everything from step **(2)** to **(5)** is part of the correlation correction algorithm.
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*Note: The first step is not required in case theoretical onsets are used instead of external picks when the parameter use_taupy_onsets is set to True. However, an existing event quakeML (.xml) file generated by PyLoT might be required for each event in case not external picks are used.*
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A detailed description of the algorithm can be found in the corresponding publication:
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*Paffrath, M., Friederich, W., and the AlpArray and AlpArray-SWATH D Working Groups: Teleseismic P waves at the AlpArray seismic network: wave fronts, absolute travel times and travel-time residuals, Solid Earth, 12, 1635–1660, https://doi.org/10.5194/se-12-1635-2021, 2021.*
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## How to use
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To use the program you have to call the main program providing two mandatory arguments: a path to the obspy dmt database folder *dmt_database_path* and the path to the PyLoT infile *pylot.in* for picking of the beam trace:
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```python pick_correlation_correction.py dmt_database_path pylot.in```
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By default, the parameter file *parameters.yaml* is used. You can use the command line option *--params* to specify a different parameter file and other optional arguments such as *-pd* for plotting detailed information or *-n 4* to use 4 cores for parallel processing:
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```python pick_correlation_correction.py dmt_database_path pylot.in --params parameters_adriaarray.yaml -pd -n 4```
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## Cross-Correlation Parameters
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The program uses the parameters in the file *parameters.yaml* by default. You can use the command line option *--params* to specify a different parameter file. An example of the parameter file is provided in the *correlation\parameters.yaml* file.
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In the top level of the parameter file the logging level *logging* can be set, as well as a list of pick phases *pick_phases* (e.g. ['P', 'S']).
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For each pick phase the different parameters can be set in the first sub-level of the parameter file, e.g.:
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```yaml
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logging: info
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pick_phases: ['P', 'S']
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P:
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min_corr_stacking: 0.8
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min_corr_export: 0.6
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[...]
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S:
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min_corr_stacking: 0.7
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[...]
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```
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The following parameters are available:
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| Parameter Name | Description | Parameter Type |
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|--------------------------------|----------------------------------------------------------------------------------------------------|----------------|
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| min_corr_stacking | Minimum correlation coefficient for building beam trace | float |
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| min_corr_export | Minimum correlation coefficient for pick export | float |
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| min_stack | Minimum number of stations for building beam trace | int |
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| t_before | Correlation window before reference pick | float |
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| t_after | Correlation window after reference pick | float |
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| cc_maxlag | Maximum shift for initial correlation | float |
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| cc_maxlag2 | Maximum shift for second (final) correlation (also for calculating pick uncertainty) | float |
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| initial_pick_outlier_threshold | Threshold for excluding large outliers of initial (AIC) picks | float |
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| export_threshold | Automatically exclude all onsets which deviate more than this threshold from corrected taup onsets | float |
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| min_picks_export | Minimum number of correlated picks for export | int |
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| min_picks_autopylot | Minimum number of reference auto picks to continue with event | int |
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| check_RMS | Do RMS check to search for restitution errors (very experimental) | bool |
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| use_taupy_onsets | Use taupy onsets as reference picks instead of external picks | bool |
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| station_list | Use the following stations as reference for stacking | list[str] |
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| use_stacked_trace | Use existing stacked trace if found (spare re-computation) | bool |
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| data_dir | obspyDMT data subdirectory (e.g. 'raw', 'processed') | str |
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| pickfile_extension | Use quakeML files (PyLoT output) with the following extension | str |
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| dt_stacking | Time difference for stacking window (in seconds) | list[float] |
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| filter_options | Filter for first correlation (rough) | dict |
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| filter_options_final | Filter for second correlation (fine) | dict |
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| filter_type | Filter type (e.g. bandpass) | str |
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| sampfreq | Sampling frequency (in Hz) | float |
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## Example Dataset
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An example dataset with waveform data, metadata and automatic picks in the obspy-dmt dataset format for testing can be found at https://zenodo.org/doi/10.5281/zenodo.13759803 |