About this tool:
NOTE: This is a beta release. We are still performing testing,
and welcome feedback from users.
The Geoelectric Field Calculator Tool was developed by NASA Goddard Space
Flight Center and DHS Science and Technology Directorate (S&T). It allows
computation of the ground geoelectric field for a given single-point geomagnetic
field time series coupled with either a one-dimensional (1D) ground conductivity,
or a three-dimensional (3D) surface impedance, ground response model. The 1D option
uses the simplified plane wave source and 1D ground formulation of the geomagnetic
induction process; the horizontal components of the geoelectric field are computed.
The tool has three options for computing the geoelectric field:
1) Select a time period of interest and geomagnetic field data recorded at
one of six different USGS stations. The 1D ground models used for the
corresponding stations are from the
physiographic CONUS model.
Please note that USGS data collected in the tool database include only the past few
years and in “real-time” quality. Please apply the second element of the
tool with data retrieved from the USGS database to use verified science quality USGS
data for historical events.
2) Upload the desired geomagnetic field data and 1D ground model. The geomagnetic data
is provided in
IAGA2002 format,
an international standard in which most observatories and databases (such as
Intermagnet) can provide data. The 1D ground
conductivity model is provided in the Earth Resistivity Model (ERM) format compatible with
that for the models found here.
Any of the 1D model files from the USGS site will work directly with the tool.
3) Upload the desired geomagnetic field data and 3D surface impedance, AKA
Electromagnetic Transfer Function (EMTF). The geomagnetic data is provided in
IAGA2002 format. The 3D surface impedance is provided in the
EMTF XML format.
Most EMTFs from that site will work directly with the tool.
NOTE! While the tool uses the well-known plane wave method, 3D surface
impedance method and verified online computational engine, the output can be
only as good as the input. Any erroneous geomagnetic field or ground model data
fed into the tool will lead to erroneous geoelectric field output. Users are
encouraged to consult with the appropriate NASA official for verifying the
quality of the geoelectric field time series before usage in further
assessments.
Acknowledgments: USGS is acknowledged for their data that is used in one of
the elements of the tool. The development of the tool was supported by DHS
S&T.
The GFCT has been tested and is supported on the
Chrome,
Firefox, and
Safari web browsers.
Curator: Chiu Wiegand
NASA Official: Dr. Masha Kuznetsova
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