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