Abstract
Solar flares rank among the most energetic events in the solar system, with extensive implications for
space weather and its impacts on Earth and space-based technologies. These explosive phenomena
release immense energy across the electromagnetic spectrum, posing risks to satellite operations,
communication systems, and power grids. Understanding the mechanisms, characteristics, and
predictive indicators of solar flares is vital for mitigating these risks and enhancing space weather
forecasting. This dissertation investigates the potential of the extreme ultraviolet (EUV) measurements
from the Geostationary Operational Environmental Satellite (GOES-16) to predict the
strength and/or duration of 1–8˚A soft X-ray (SXR) solar flares. Analyzing X- and M-class flares
observed from 2017 to 2024, the study focuses on the correlations between EUV spectral lines
(Lyman-alpha, He II, and the Mg II index) and SXR emissions. Among these, He II emerges as the
most predictive spectral line, demonstrating a robust correlation with SXR durations (r = 0.60 for
M-class and r = 0.74 for X-class flares) and a moderate correlation with flare strength (r = 0.53).
He II enhancements exceeding 20% above the background are a strong indicator of X-class flares,
with less than 1% of M-class flares exhibiting such significant enhancements. He II emissions peak
ahead of SXR emissions in 67% of cases, with an average lead time of approximately 3.6 minutes
for X-class flares and 4.4 for M-class flares, highlighting their utility for nowcasting flare activity.
Lyman-alpha, while exhibiting weaker correlations than He II, provides valuable early indicators
of flare activity. Its durations correlate moderately with SXR durations (r = 0.50 for M-class and
r = 0.63 for X-class flares), and its peak flux shows a low correlation with flare strength (r = 0.32).
Lyman-alpha emissions precede SXR emissions in 68% of cases, with an average lead time of 4.8
minutes for X-class flares and 5.2 minutes for M-class flares. The Mg II index demonstrates moderate
correlations with SXR durations, with a correlation coefficient of (r = 0.47 for M-class and r = 0.69
for X-class flares). Its strength correlates less strongly with SXR strength (r = 0.43) but provides
insights into flare dynamics. Mg II emissions peak ahead of SXR emissions in 64% of cases, with an
average lead time of 4.7 minutes for X-class flares and 5 minutes for M-class flares. These findings
emphasize the diagnostic potential of the EUV spectral lines as a predictive tool for solar flare
dynamics, reinforcing their importance in improving space weather forecasting capabilities. The
insights gained also contribute to the broader understanding of flare behavior and the interplay
between EUV and X-ray emissions, advancing our ability to monitor and respond to solar activity.