Comparison of Equatorial Plasma Bubbles and Spread-F Observations Using
2-D GPS ΔTEC Data Maps and Ionosonde Measurements over the South
American Sector
Abstract
We report our cross-validation of equatorial plasma bubble (EPB)
observations based on 2-D ΔTEC data maps over the South American sector,
against equatorial spread-F (ESF) observations based on digisonde
measurements at several locations. The 2-D ΔTEC data maps were derived
using a GPS TEC data detrending procedure [Pradipta et al., 2015]
that is inherently capable of distinguishing between wavelike
fluctuations associated with traveling ionospheric disturbances (TIDs)
and deep depletions associated with EPBs. The data detrending was
performed for TEC signals along individual ionospheric piercing point
(IPP) trajectories from individual stations, before spatially
interpolating the ΔTEC values into a fine 0.2 deg x 0.2 deg geographic
latitude/longitude grid. We validated the EPB/depletion observations
from these 2-D ΔTEC data maps against digisonde observations of ESF
occurrences at Jicamarca (JI91J), Cachoeira Paulista (CAJ2M), and
Fortaleza (FZA0M) using data recorded in 2011. A general agreement was
found between the EPB and ESF occurrences. Over Jicamarca: 55.1% fall
within the EPB=YES & ESF=YES category, 20.6% fall within the EPB=NO &
EPB=NO category, 24.4% fall within the EPB=NO & ESF=YES category, and
0% fall within the EPB=YES & ESF=NO category. Over Cachoeira Paulista:
48.5% fall within the EPB=YES & ESF=YES category, 37.4% fall within
the EPB=NO & EPB=NO category, 13.2% fall within the EPB=NO & ESF=YES
category, and 0.8% fall within the EPB=YES & ESF=NO category. Over
Fortaleza: 68.8% fall within the EPB=YES & ESF=YES category, 10.4%
fall within the EPB=NO & EPB=NO category, 20.2% fall within the EPB=NO
& ESF=YES category, and 0.6% fall within the EPB=YES & ESF=NO
category. The classification process of EPB/ESF occurrences (+’s) and
no-occurrences (-’s) in this validation work also points at the
possibility of performing combinatoric pattern analyses on EPB/ESF
occurrence likelihood. This type of analysis may be useful in assessing
the fundamental limit of EPB/ESF occurrence predictability that can be
theoretically achieved.