Tuesday, September 25, 2012

Paper finds 'brightening' of sunshine hours since 1980

A paper published in the Journal of Geophysical Research examined sunshine hours over the Iberian Peninsula from 1961-2004. The authors find a dimming of sunshine occurred from 1961 to the early 1980's, corresponding to the ice age scare of the time. Conversely, the authors find, "Since the early 1980s, the [sunshine duration] series exhibit an upward trend or “brightening,” which corresponds to the subsequent warming period. The authors also find a relationship between sunshine and atmospheric circulation patterns, stating, "Finally and perhaps surprisingly, the [total cloud cover] residual [sunshine duration] series exhibits a statistically significant relationship with a regional atmospheric circulation pattern during spring, summer, and autumn." The IPCC, however, dismisses the role of the Sun in climate change by only examining small changes in Total Solar Irradiance [TSI], while ignoring sunshine hours at Earth's surface, the effect of cloud variations on sunshine, and amplifying factors on sunshine such as clouds/cosmic rays, ozone, large changes in solar UV and the solar magnetic field within and between solar cycles, solar effects on ocean oscillations and atmospheric patterns, etc., etc.

New paper finds significant increase in solar UV radiation over past 14 years

Daily mean sunshine hours anomaly over the Iberian Peninsula for cloud-free sky conditions

Arturo Sanchez‐Lorenzo
Group of Climatology, Department of Physical Geography, University of Barcelona, Barcelona, Spain
Josep Calbó
Group of Environmental Physics, University of Girona, Girona, Spain
Michele Brunetti
Institute of Atmospheric Sciences and Climate, Italian National Research Council (ISAC‐CNR), Bologna, Italy
Clara Deser
National Center for Atmospheric Research, Boulder, Colorado, USA
This study analyzes the spatial and temporal changes in sunshine duration (SunDu) and total cloud cover (TCC) over the Iberian Peninsula (IP) and four subregions during 1961–2004 using high‐quality, homogenized data sets. The analyses confirm that over most of the IP and in most seasons, SunDu and TCC variations are strongly negatively correlated, with absolute values ∼0.8–0.9. Somewhat weaker correlations (0.5–0.6) are found in the southern portion of the IP in summer. A large discrepancy between the SunDu and TCC records occurs from the 1960s until the early 1980s when the SunDu series shows a decrease that it is not associated with an increase in TCC. This negative trend or “dimming” is even more pronounced after removing the effects of TCC via linear regression. Since the early 1980s, the SunDu and TCC residual SunDu series exhibit an upward trend or “brightening.” In addition to the long‐term dimming and brightening, the volcanic eruptions of El Chichon and Mount Pinatubo are clearly evident in the TCC residual SunDu record. The TCC and SunDu records over the IP are well correlated with sea level pressure (SLP), with above normal TCC and below normal SunDu corresponding to below normal SLP locally in all seasons. The TCC and SunDu related SLP changes over the IP in winter and spring are part of a larger‐scale north‐south dipole pattern that extends over the entire Euro‐Atlantic sector. Other more regional atmospheric circulation patterns, identified from rotated principal component analysis, are also linked to TCC and SunDu variations over the IP. Finally and perhaps surprisingly, the TCC residual SunDu series exhibits a statistically significant relationship with a regional atmospheric circulation pattern during spring, summer, and autumn.

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