#!/usr/bin/env python # coding: utf-8 #
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Noise
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Lab: Probabilistic Power Spectral Densities
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# # # Seismo-Live: http://seismo-live.org # # ##### Authors: # * Tobias Megies ([@megies](https://github.com/megies)) # # --- # In[1]: get_ipython().run_line_magic('matplotlib', 'inline') import matplotlib.pyplot as plt plt.style.use("bmh") plt.rcParams['figure.figsize'] = 10, 6 # * read waveform data from file `data/GR.FUR..BHN.D.2015.361` (station `FUR`, [LMU geophysical observatory in Fürstenfeldbruck](https://www.geophysik.uni-muenchen.de/observatory/seismology)) # * read corresponding station metadata from file `data/station_FUR.stationxml` # * print info on both waveforms and station metadata # In[2]: from obspy import read, read_inventory st = read("data/GR.FUR..BHN.D.2015.361") inv = read_inventory("data/station_FUR.stationxml") print(st) print(inv) inv.plot(projection="ortho"); # * compute probabilistic power spectral densities using `PPSD` class from obspy.signal, see http://docs.obspy.org/tutorial/code_snippets/probabilistic_power_spectral_density.html (but use the inventory you read from StationXML as metadata) # * plot the processed `PPSD` (`plot()` method attached to `PPSD` object) # In[3]: from obspy.signal import PPSD tr = st[0] ppsd = PPSD(stats=tr.stats, metadata=inv) ppsd.add(tr) ppsd.plot() # Since longer term stacks would need too much waveform data and take way too long to compute, we prepared one year continuous data preprocessed for a single channel of station `FUR` to play with.. # # * load long term pre-computed PPSD from file `PPSD_FUR_HHN.npz` using `PPSD`'s `load_npz()` staticmethod (i.e. it is called directly from the class, not an instance object of the class) # * plot the PPSD (default is full time-range, depending on how much data and spread is in the data, adjust `max_percentage` option of `plot()` option) (might take a couple of minutes..!) # * do a cumulative plot (which is good to judge non-exceedance percentage dB thresholds) # In[4]: from obspy.signal import PPSD ppsd = PPSD.load_npz("data/PPSD_FUR_HHN.npz") # In[5]: ppsd.plot(max_percentage=10) ppsd.plot(cumulative=True) # * do different stacks of the data using the [`calculate_histogram()` (see docs!)](http://docs.obspy.org/packages/autogen/obspy.signal.spectral_estimation.PPSD.calculate_histogram.html) method of `PPSD` and visualize them # * compare differences in different frequency bands qualitatively (anthropogenic vs. "natural" noise).. # * nighttime stack, daytime stack # * advanced exercise: Use the `callback` option and use some crazy custom callback function in `calculate_histogram()`, e.g. stack together all data from birthdays in your family.. or all German holidays + Sundays in the time span.. or from dates of some bands' concerts on a tour.. etc. # In[6]: ppsd.calculate_histogram(time_of_weekday=[(-1, 0, 2), (-1, 22, 24)]) ppsd.plot(max_percentage=10) ppsd.calculate_histogram(time_of_weekday=[(-1, 8, 16)]) ppsd.plot(max_percentage=10) # * do different stacks of the data using the [`calculate_histogram()` (see docs!)](http://docs.obspy.org/packages/autogen/obspy.signal.spectral_estimation.PPSD.calculate_histogram.html) method of `PPSD` and visualize them # * compare differences in different frequency bands qualitatively (anthropogenic vs. "natural" noise).. # * weekdays stack, weekend stack # In[7]: ppsd.calculate_histogram(time_of_weekday=[(1, 0, 24), (2, 0, 24), (3, 0, 24), (4, 0, 24), (5, 0, 24)]) ppsd.plot(max_percentage=10) ppsd.calculate_histogram(time_of_weekday=[(6, 0, 24), (7, 0, 24)]) ppsd.plot(max_percentage=10) # * do different stacks of the data using the [`calculate_histogram()` (see docs!)](http://docs.obspy.org/packages/autogen/obspy.signal.spectral_estimation.PPSD.calculate_histogram.html) method of `PPSD` and visualize them # * compare differences in different frequency bands qualitatively (anthropogenic vs. "natural" noise).. # * seasonal stacks (e.g. northern hemisphere autumn vs. spring/summer, ...) # In[8]: ppsd.calculate_histogram(month=[10, 11, 12, 1]) ppsd.plot(max_percentage=10) ppsd.calculate_histogram(month=[4, 5, 6, 7]) ppsd.plot(max_percentage=10) # * do different stacks of the data using the [`calculate_histogram()` (see docs!)](http://docs.obspy.org/packages/autogen/obspy.signal.spectral_estimation.PPSD.calculate_histogram.html) method of `PPSD` and visualize them # * compare differences in different frequency bands qualitatively (anthropogenic vs. "natural" noise).. # * stacks by specific month # * maybe even combine several of above restrictions.. (e.g. only nighttime on weekends) # In[ ]: