Autori: M. Voiculescu, I. Usoskin
Editorial: doi:10.1088/1748-9326/7/4/044004, Environ. Res. Lett. , 7, 2012.
A consensus regarding the impact of solar variability on cloud cover is far from being reached.
Moreover, the impact of cloud cover on climate is among the least understood of all climate
components. This motivated us to analyze the persistence of solar signals in cloud cover for
the time interval 1984–2009, covering two full solar cycles. A spatial and temporal
investigation of the response of low, middle and high cloud data to cosmic ray induced
ionization (CRII) and UV irradiance (UVI) is performed in terms of coherence analysis of the
two signals. For some key geographical regions the response of clouds to UVI and CRII is
persistent over the entire time interval indicating a real link. In other regions, however, the
relation is not consistent, being intermittent or out of phase, suggesting that some correlations
are spurious. The constant in phase or anti-phase relationship between clouds and solar
proxies over some regions, especially for low clouds with UVI and CRII, middle clouds with
UVI and high clouds with CRII, definitely requires more study. Our results show that solar
signatures in cloud cover persist in some key climate-defining regions for the entire time
period and supports the idea that, if existing, solar effects are not visible at the global level and
any analysis of solar effects on cloud cover (and, consequently, on climate) should be done at
the regional level.
Cuvinte cheie: solar-climate, clouds, UV irradiance, cosmic rays, climate variability