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Geomag Algorithms API

Geomag algorithms is built around the ObsPy, SciPy, and NumPy frameworks, which provide many tools for processing timeseries and other scientific data.

Architecture

  • Data are read into a standard Internal Data Format by Input/Output factories.
  • Algorithms process data.
  • A command line script geomag.py uses a Controller to manage input, optional processing, and output of data.

Architecture diagram

Internal Data Format

ObsPy Trace and Stream objects are used to hold timeseries data.

  • Custom geomag metadata properties are added to each Trace object's Stats by IO factories.
  • Data gaps are represented as numpy.nan.
  • Times use obspy.core.UTCDateTime.
  • Most channels use nT units.
  • Angular channels use radians.

Input/Output factories

Base class is geomagio.TimeseriesFactory. Exception base class is geomagio.TimeseriesFactoryException.

  • Edge/Earthworm geomagio.edge.EdgeFactory
  • IAGA 2002 geomagio.iaga2002.IAGA2002Factory
  • IMF V2.83 (Input Only) geomagio.imfv283.IMFV283Factory
  • PCDCP geomagio.pcdcp.PCDCPFactory

Algorithms

Base class is geomagio.algorithm.Algorithm Exception base class is geomagio.algorithm.AlgorithmException

  • Adjusted geomagio.algorithm.AdjustedAlgorithm
  • Delta F geomagio.algorithm.DeltaFAlgorithm
  • XYZ geomagio.algorithm.XYZAlgorithm

Example

The following example:

  • Uses EdgeFactory to read data from the USGS EDGE server
  • Uses XYZAlgorithm to change the data from observatory channels (H, E, Z, F) to geographic channels (X, Y, Z, F).
  • Plots the data using matplotlib
from geomagio.algorithm import XYZAlgorithm
from geomagio.edge import EdgeFactory
from obspy.core import UTCDateTime

# read data from the USGS EDGE server
factory = EdgeFactory(host='cwbpub.cr.usgs.gov', port=2060)
hezf = factory.get_timeseries(
        observatory='BOU',
        interval='minute',
        type='variation',
        channels=('H', 'E', 'Z', 'F'),
        starttime=UTCDateTime('2015-11-01T00:00:00Z'),
        endtime=UTCDateTime('2015-11-01T23:59:59Z'))

# convert from HEZF channels to XYZF channels
algorithm = XYZAlgorithm(informat='obs', outformat='geo')
xyzf = algorithm.process(hezf)

# open interactive matplotlib plot
xyzf.plot()