Poster's note : tropospheric aerosol mechanisms have been postulated as levers for regional geoengineering programs. The quantification of their effects, as below, aids intervention design.
http://www.nature.com/srep/2014/141106/srep06929/full/srep06929.html Attribution of the United States “warming hole”: Aerosol indirect effect and precipitable water vapor Shaocai Yu, Kiran Alapaty, Rohit Mathur, Jonathan Pleim, Yuanhang Zhang, Chris Nolte, Brian Eder,Kristen Foley & Tatsuya Nagashima Scientific Reports 4, Article number: 6929 doi:10.1038/srep06929 Published 06 November 2014 Aerosols can influence the climate indirectly by acting as cloud condensation nuclei and/or ice nuclei, thereby modifying cloud optical properties. In contrast to the widespread global warming, the central and south central United States display a noteworthy overall cooling trend during the 20thcentury, with an especially striking cooling trend in summertime daily maximum temperature (Tmax) (termed the U.S. “warming hole”). Here we used observations of temperature, shortwave cloud forcing (SWCF), longwave cloud forcing (LWCF), aerosol optical depth and precipitable water vapor as well as global coupled climate models to explore the attribution of the “warming hole”. We find that the observed cooling trend in summer Tmax can be attributed mainly to SWCF due to aerosols with offset from the greenhouse effect of precipitable water vapor. A global coupled climate model reveals that the observed “warming hole” can be produced only when the aerosol fields are simulated with a reasonable degree of accuracy as this is necessary for accurate simulation of SWCF over the region. These results provide compelling evidence of the role of the aerosol indirect effect in cooling regional climate on the Earth. Our results reaffirm that LWCF can warm both winter Tmax and Tmin. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
