A paper published today in the Journal of Geophysical Research finds that a natural atmospheric oscillation, the Southern Annular Mode, is correlated to significant increases in cloud cover resulting in “large scale” local cooling of approximately -2.5C. All climate models falsely assume clouds result in net positive feedback and increased temperatures, however this new paper and several others show clouds instead result in net negative feedback and cooling.
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| Large localized reductions in temperature result from increased clouds with a ~1 day time lag |
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 117, D13103, 7 PP., 2012
doi:10.1029/2012JD017626
doi:10.1029/2012JD017626
Key Points
- Sudden regional increases in cloud cover are detected over S. America
- Changes linked to the Southern Annular Mode
- The cloud changes are associated with regional temperature reductions
Benjamin A. Laken
Instituto de Astrofísica de Canarias, La Laguna, Spain
Department of Astrophysics, Faculty of Physics, Universidad de La Laguna, La Laguna, Spain
Enric Pallé
Instituto de Astrofísica de Canarias, La Laguna, Spain
Department of Astrophysics, Faculty of Physics, Universidad de La Laguna, La Laguna, Spain
This work investigates the cause and effects of extreme changes in synoptic-scale cloud cover operating at daily timescales using a variety of satellite-based and reanalysis data sets. It is found that the largest sudden increases detected in globally averaged cloud cover over the last ten years of satellite-based observations occur following positively correlated shifts in the phase of the Southern Annular Mode (SAM) index. The associated pressure anomalies are found to generate frontal cloud formation over large areas of the South American continent, increasing regional cloud cover by up to 20%; these changes are correlated to statistically significant reductions in local temperatures of approximately −2.5°C with a +1 day time lag, indicating the SAM index is associated with large scale weather fluctuations over South America.