2008, Petoukhov, V., Eliseev, A.V., Klein, R., Oesterle, H.

Based on the ERA40 data for 1976-2002 we calculated skewnesses and mixed third-order statistical moments (TOMs) for the synoptic variations [with (2.5-6) d timescales]of horizontal winds, temperature, vertical velocity and the specific humidity in Eulerian coordinates. All these variables show skewnesses which markedly deviate from zero, basically at the entries and the outlets of the mid-latitude storm tracks. In these regions, high values of skewness for vertical velocity, temperature and the specific humidity are revealed throughout the entire free troposphere, while the marked skewnesses for horizontal winds are traced in the lower free troposphere. We found a notable deviation of the synoptic-component statistics from the Gaussian statistics. We also made an estimate of the contribution from TOMs to the prognostic equations for the synoptic-scale kinetic energy and the meridional fluxes of sensible and latent heat, which appeared to be non-negligible, mainly in the storm tracks in winter. Our analysis attests that the most pronounced contribution of TOMs to the aforementioned equations comes from the self-advection by the horizontal synoptic-scale motions, while the TOMs induced by the metric terms in the original equations, and specifically the TOMs associated with the vertical self-advection by the synoptic-scale motions, are much less important.

2008, Bauer, E., Petoukhov, V., Ganopolski, A., Eliseev, A.V.

The Earth system model CLIMBER-2 is extended by a scheme for calculating the climatic response to anthropogenic sulphur dioxide emissions. The scheme calculates the direct radiative forcing, the first indirect cloud albedo effect, and the second indirect cloud lifetime effect induced by geographically resolved sulphate aerosol burden. The simulated anthropogenic sulphate aerosol burden in the year 2000 amounts to 0.47 TgS. The best guesses for the radiative forcing due to the direct effect are -0.4 W m-2 and for the decrease in short-wave radiation due to all aerosol effects -0.8 W m-2. The simulated global warming by 1 K from 1850 to 2000 caused by anthropogenic greenhouse gases reduces to 0.6 K when the sulphate aerosol effects are included. The model's hydrological sensitivity of 4%/K is decreased by the second indirect effect to 0.8%/K. The quality of the geographically distributed climatic response to the historic emissions of sulphur dioxide and greenhouse gases makes the extended model relevant to computational efficient investigations of future climate change scenarios.