We have developed SOCOL as a combination of MAECHAM4 (Middle Atmosphere version of the "European Center/Hamburg Model 4") General Circulation Model (Manzini et al.,1997, Roeckner et al., 1996) and a modified version of the UIUC atmospheric chemistry-transport model described by Rozanov et al. (1999, 2001) and Egorova et al. (2001). SOCOL is a spectral general circulation model with T30 horizontal truncation (Gaussian Grid 3.75?x3.75?). In the vertical direction it has 39 layers spanning the atmosphere from the surface to 0.01hPa. The vertical resolution in the lower stratosphere is about 2 km. The chemical-transport part of the model simulates 41 chemical species from the oxygen, hydrogen, nitrogen, carbon, chlorine and bromine groups, which are determined by 202 gas-phase and photolysis reactions. The model also takes into account 16 heterogeneous reactions on/in sulfate aerosol (binary and ternary solutions) and polar stratospheric cloud particles. The chemical solver is based on the pure implicit iterative Newton-Raphson scheme. The reaction coefficients are taken from JPL-1997, 2000 publications. The photolysis rates are calculated at every 2-hour long chemical-transport step using a look-up-table approach. This updated parameterization takes into account the photo-dissociations in the spectral region between 120 and 170 nm, which is significant for the chemistry of the mesosphere. The transport of all considered species is calculated using the hybrid numerical advection scheme (Zubov et al., 1999). As a source for the chemical species we use the prescribed mixing ratio of the source gases in the planetary boundary layer, prescribed NOx sources from airplanes and lightning. The GCM part of the model provides the horizontal and vertical winds, temperature and humidity in the troposphere for the chemistry-transport part. The chemistry-transport part returns the 3-D fields of ozone and stratospheric water vapor mixing ratio, which are then used in GCM radiation code to calculate net radiative heating. As the MAECHAM4 radiation code has been designed mainly for tropospheric studies we have added a parameterization of heating rates due to ozone and oxygen absorption (Strobel, 1978), which is rather important in the stratosphere and mesosphere.
SOCOL has been ported on desktop personal computers (PC). A 10-year long simulation takes us about 40 days of wall-clock time that allows us to perform multiyear integrations. At the moment we have completed first 40-year long control simulation for present day sea surface temperature (SST), sea ice (SI), greenhouse gas (GG) and ozone destroying substances (ODS) distributions. Temperature, zonal wind and species distributions simulated with SOCOL have been compared with available observational data and some other model results. The observed zonal and monthly averaged temperature for the atmosphere up to 1 hPa have been taken from the UK Meteorological Office (UKMO) assimilation data set for 1992-2002. Total ozone data have been taken from Nimbus 7, Meteor 3, ADEOS, Earth Probe TIROS Operational Vertical Sounder (TOVS), and Global Ozone Monitoring Experiment measurements and averaged over 10 (1993-2002) years. For the comparison of the species (ozone, water vapor, and methane, HCl) and zonal wind distributions in the stratosphere we used the UARS Reference Atmosphere Project (URAP) data set.
According to the validation results we can make a conclusion that SOCOL is capable of reproducing the observed climatology and can be used for studies of solar-climate connection issues. The model description and validation results have been widely presented and an extensive technical report is under preparation. Some results in comparison with observational data are presented in this site (socol_validation.pdf).
References:
Manzini E., McFarlane N.A., and McLandress C., Impact of the Doppler Spread Parameterization on the simulation of the middle atmosphere circulation using the MA/ECHAM4 general circulation model, 1997, J.Geophys. Res., 102, 25751-25762.
Roeckner E., et al., The atmospheric general circulation model ECHAM4: Model descreption and simulation of the present day climate, Tech.Rep. 218, Max Planck Ins. for Meteorol., Hamburg, Germany, 1996.
Rozanov, E.V., M.E. Schlesinger, V.A. Zubov, F. Yang, and N. G. Andronova, The UIUC three-dimensional stratospheric chemical transport model: Descriprion and evaluation of the simulated source gases and ozone, 1999, J. Geophys. Res., 104, D9, p. 11755-11781.
Rozanov, E.V., M.E. Schlesinger, and V.A. Zubov, The University of Illinois, Urbana-Champaign three-dimensional stratosphere-troposphere general circulation model with interactive ozone photochemistry: Fifteen-year control run climatology, J. Geophys. Res., 2001, 106, D21, p. 27233-27254.
Egorova, T. A., E. V. Rozanov, M. E. Schlesinger, N. G. Andronova, S. L. Malyshev, V. A. Zubov, and I. L. Karol, Assessment of the effect of the Montreal Protocol on atmospheric ozone, 2001, Geoph. Res. Lett., 28, N12, 2389-2392.
Zubov V., Rozanov E., and Schlesinger M., Hybrid scheme for tree-dimensional advective transport, 1999, Mon. Wea. Rev., 127, p.1335-1346.
Strobel, D. F., Parameterization of the atmospheric heating rate from 15 to 120 km due to O2 and O3 absorption of solar radiation, 1978, J. Geophys. Res., 83, 6225-6230, 1978.
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