New paper finds 'up to 30% discrepancy between modeled and observed solar energy absorbed by the atmosphere'

More problems for the climate models: A paper published today in Geophysical Research Letters finds that there is "up to 30% discrepancy between the modeled and the observed solar energy absorbed by the atmosphere."  The authors attribute part of this large discrepancy, which would alone have a greater radiative forcing effect than all of the man-made CO2 in the atmosphere, to water vapor absorption in the near UV region, "But the magnitude of water vapor absorption in the near UV region at wavelengths shorter than 384 nm is not known." The authors note, "Water vapor is [the most] important greenhouse gas in the earth's atmosphere" and set out to discover [apparently for the first time] "The effect of the water vapor absorption in the 290-350 nm region on the modeled radiation flux at the ground level."

The influence of water vapor absorption in the 290-350 nm region on solar radiance: Laboratory studies and model simulation

Juan Du, Li Huang, Qilong Min, Lei Zhu

Water vapor is an important greenhouse gas in the earth's atmosphere. Absorption of the solar radiation by water vapor in the near UV region may partially account for the up to 30% discrepancy between the modeled and the observed solar energy absorbed by the atmosphere. But the magnitude of water vapor absorption in the near UV region at wavelengths shorter than 384 nm is not known. We have determined absorption cross sections of water vapor at 5 nm intervals in the 290-350 nm region, by using cavity ring-down spectroscopy. Water vapor cross section values range from 2.94 × 10-24 to 2.13 × 10-25 cm2/molecule in the wavelength region studied. The effect of the water vapor absorption in the 290-350 nm region on the modeled radiation flux at the ground level has been evaluated using radiative transfer model.