New lightning-derived vertical total electron content data provides
unique global ionospheric measurements
Abstract
A newly-released, novel ionospheric dataset of global gridded vertical
total electron content (VTEC) is introduced in this paper. This VTEC
dataset, provided by Los Alamos National Laboratory (LANL), is derived
from very-high frequency (VHF; defined as 30-300 MHz) broadband
radio-frequency (RF) measurements of lightning made by U.S. Department
of Defense sensing systems on board Global Positioning System (GPS)
satellites. This paper presents the new dataset (LANL VTEC), discusses
the errors inherent in VHF TEC estimation due to ionospheric dispersion,
and compares the LANL VTEC to two community standard VTEC gridded
products: Jet Propulsion Laboratory’s Global Ionospheric Model (JPL GIM)
and the CEDAR community’s Open Madrigal VTEC gridded measurements of
L-band GNSS (global navigation satellite systems) TEC. We find that the
LANL VTEC data has an offset of 3 TECU from CEDAR Madrigal GNSS VTEC,
and a full-width-half-maximum (FWHM) of 6 TECU. In comparison, the
offset between LANL VTEC and the JPL GIM model is -3 TECU, but with a
FWHM of 5 TECU. We also compare to Jason-3 VTEC measurements over the
ocean, finding an offset of less than 0.5 TECU and a FWHM of <
5 TECU. Because this technique uses a completely different methodology
to determine TEC, the sources of errors are distinct from the typical
ground-based GNSS L-band (GHz) TEC measurements. Also, because it is
derived from RF lightning signals, this dataset provides measurements in
regions that are not well covered by ground-based GPS measurements, such
as over oceans and over central Africa.