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Solar activity during 2007--2009 was very low, causing anomalously lowthermospheric density. A comparison of solar extreme ultraviolet (EUV)irradiance in the He II spectral band (26 to 34 nm) from the Solar Extremeultraviolet Monitor (SEM), one of instruments on the Charge Element and IsotopeAnalysis System (CELIAS) onboard of the Solar and Heliospheric Observatory(SOHO) for the two latest solar minima showed a decrease of the absoluteirradiance of about 15 +- 6 % during the solar minimum between Cycles 23 and 24compared with the Cycles 22/23 minimum when a yearly running mean filter wasused. We found that some local, shorter-term minima including those with thesame absolute EUV flux in the SEM spectral band show a larger concentration ofspatial power in the global network structure from the 30.4 nm SOHO Extremeultraviolet Imaging Telescope (EIT) images for the local minimum of 1996compared with the minima of 2008--2011. We interpret this larger concentrationof spatial power in the transition region's global network structure as alarger number of larger area features on the solar disk. Such changes in theglobal network structure during solar minima may characterize, in part, thegeo-effectiveness of the solar He II EUV irradiance in addition to theestimations based on its absolute levels.

A Change of Solar He II EUV Global Network Structure of the Transition Region as an Indicator of Geo-Effectiveness of Solar Minima