lördag 2 januari 2010

The Greenhouse Effect According to Spencer

Roy Spencer explains the fundamentals of global climate as follows:
  • The climate of the Earth is profoundly affected by two competing processes: the greenhouse effect, which acts to warm the lower atmosphere and cool the upper atmosphere, and atmospheric convection (thermals, clouds, precipitation) which does just the opposite: cools the lower atmosphere and warms the upper atmosphere.
  • While we usually only discuss the greenhouse effect in the context of global warming (that is, the theory that adding more carbon dioxide to the atmosphere will lead to higher temperatures in the lower atmosphere), it turns out that the greenhouse effect has a more fundamental role: there would be no weather on Earth without the greenhouse effect.
  • As Dick Lindzen alluded to back in 1990, while everyone seems to understand that the greenhouse effect warms the Earth’s surface, few people are aware of the fact that weather processes greatly limit that warming. And one very real possibility is that the 1 deg. C direct warming effect of doubling our atmospheric CO2 concentration by late in this century will be mitigated by the cooling effects of weather to a value closer to 0.5 deg. C or so (about 1 deg. F.) This is much less than is being predicted by the UN’s Intergovernmental Panel on Climate Change or by NASA’s James Hansen, who believe that weather changes will amplify, rather than reduce, that warming.
To model climate we need to model weather and to model weather we need to solve the full 3d Navier-Stokes equations including the crucial vertical turbulent motion and heat exchange.

Current computational models us a simplified form of the Navier-Stokes equations where the 
vertical motion is averaged. No wonder that these models cannot predict neither weather nor climate, as evidenced in It has a gigantic supercomputer, 1,500 staff and a £170m-a-year budget. So why does the Met Office get it so wrong? by Richard North, Daily Mail.

Computing turbulent solutions of the full 3d Navier-Stokes is now possible, and may open new possibilities in climate and weather modeling/prediction, which we are currently exploring...

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