@InProceedings{CaraballoAlveHartBarb:2018:PRCO,
author = "Caraballo, Ramon and Alves, Livia Ribeiro and Hartmann, G. and
Barbosa, Cleiton",
affiliation = "{Universidad de la Rep{\'u}blica del Uruguay} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {Universidade Estadual
de Campinhas (UNICAMP)} and {Observat{\'o}rio Nacional
(ON/MCTI)}",
title = "Benchmarking GIC estimates at low latitudes using data by second:
PROS and CONS",
year = "2018",
organization = "Latin American Conference on Space Geophysics, 11. (COLAGE)",
abstract = "Geomagnetic Induced currents (GIC) are becoming a common subject
of study at low-to-mid latitude around the world. Also, a crescent
observational evidence supporting the existence of significative
GIC estimates or measures on several infrastructures. Several
works have been published in the last four years addressing GIC
modeling or measurements. Mostly of the GIC studies rely on three
key inputs: geomagnetic data, geophysical data and electrical
parameters of the system under study. From this point of view,
geomagnetic data quality is rarely mentioned, maybe by the fact
that the most used geomagnetic data comes in form of oneminute
means. Usually, one-minute means can be obtained by a standard
procedures mainly based on those provided by IAGA for all magnetic
observatories around the world which are part of the INTERMAGNET
network. Despite it is a great advantage to get data from more
than 250 magnetic observatories around the world in a common
format, one-second data it is still scarce and only available from
a reduced number of observatories on South America under request.
Geomagnetic variations at a one-minute sampling period is too slow
to catch the high frequency parts of the geomagnetic spectrum.
When dealing with the geomagnetic variations close to the storm
onset, where sudden impulses are more prone to occur, one-minute
data might not be sufficient faster to take account of the rapid
change in the field components. As a result, the estimated GIC
often underestimates the real one. As the geomagnetic variations
are the first input in any GIC calculations, they exerts a great
leverage on the final results. No matter the averaging method used
to produce one-minute data, they produce a strong smoothing by
filtering much of the rapid time variations on the original
signal. Mostly of the fine grained structures on the magnetograms
are lost in this process leading to a rather flattened version of
the original signal. As the sampling frequency increases the more
detailed structures in the geomagnetic variations leads to more
weird peaks in the calculated GIC. Here, we address this problem
intending to assess the fraction of signal power lost by the use
of one-minute data. The methodology used consisted in assess the
estimated GIC for two specific power grids in Uruguay and Brazil,
respectively, during three major geomagnetic storms of the solar
cycle 24. The GIC calculated using both one-minute and one-second
data respectively, for those power grids was compared to study the
effect in the final estimates. In this case, the round mean square
(rms) of differences and the power spectral density of both
results can provide and outlook of the fraction of energy lost by
the averaging process in the one-minute case. In order to provide
the best estimation possible which result in a valuable tool for
the forecasting GIC events.",
conference-location = "Buenos Aires, Argentina",
conference-year = "16-20 abr.",
language = "en",
urlaccessdate = "04 jun. 2024"
}