Solar minimum 2008-2009

The descending phase of solar cycle 23 was long and gradual, and during 2008–2009, solar activity became extremely low. In late 2009, solar activity finally started to increase, but the period between mid-2007 and mid-2009 was one of the longest of recent solar minima. Recently, several interesting papers have been published about this subject. The work of Fröhlich (2010) has shown that the value of total solar irradiance during the solar minimum of 2008-2009 was more than 0.2 Wm−2 smaller than during the last minimum in 1996. Solomon et al. (2010) have indicated that that solar extreme ultraviolet irradiance levels during the solar minimum of 2008-2009 were also lower than they were during the previous solar minimum. Haigh et al. (2010) have shown that these spectral changes appear to have led to a significant decline from 2004 to 2007 in stratospheric ozone below an altitude of 45 km. Garcia (2010) states that these implications for Earth’s atmosphere must be viewed as provisional.