Impact of the Doppler spread parameterization on the simulation of the middle atmosphere circulation using the MA/ECHAM4 general circulation model

Abstract

Abstract.The zonal mean circulation of the middle atmosphere simulated by a general circulation model that includes the Doppler spread parameterization of gravity-wave momentum deposition is presented. To illustrate the impact of the parameterization, this simulation is compared to another obtained by using Rayleigh friction instead. It is found that the Doppler spread parameterization improves the extratropical zonal mean circulation in the mesosphere by reducing the strength of the zonal winds above the jet maximum. The parameterization also improves the simulation of the equatorial semiannual oscillation in the zonal mean zonal wind at the stratopause by enhancing the eastward phase and its downward propagation.

Earth System Chemistry integrated Modelling (ESCiMo) with the Modular Earth Submodel System (MESSy) version 2.51

“…The parameter is used in the calculation of the cutoff wave number in each model level, controlling the wave number at which the wave breakdown begins (Manzini et al, 1997). Decreasing rmscon leads to a larger cutoff wave number and wave breaking occurs less often, which has the effect of reducing the disturbance of the polar vortex by deposited momentum flux in the stratosphere and mesosphere.…”

Interannual variation patterns of total ozone and lower stratospheric temperature in observations and model simulations

“…With more levels near the tropopause, E39/C is targeted more on processes around the tropopause Schnadt et al, 2002;Schnadt and Dameris, 2003). MAECHAM4-CHEM, on the other hand, is a full troposphere-stratosphere-mesosphere model (Manzini et al, 1997;Manzini et al, 2003). It includes better radiation and dissipation processes, especially momentum deposition by dissipating gravity wave spectra, which is parameterized in MAECHAM4-CHEM (Manzini and McFarlane, 1998), but not in E39/C.…”

“…The simulations were performed with two models derived from the European Center HAMburg version 4 (Roeckner et al, 1996), and the MA-ECHAM4 (Manzini et al, 1997) general circulation models: ECHAM4.L39(DLR)/CHEM, called E39/C hereafter, and MAECHAM4-CHEM. Both are based on full coupling of the general circulation (GCM) model with the chemistry model CHEM (Steil et al, 1998).…”

The Antarctic Oscillation Structure in an AOGCM with Interactive Stratospheric Ozone

“…A chemistry part based on the MECCA chemistry module ("Module Efficiently Calculating the Chemistry of the Atmosphere" see Sander et al [12]) was implemented. The model includes the 39-level middle atmosphere version (see Manzini et al [13] and Manzini and McFarlane [14]) of the atmosphere model ECHAM4 (see Roeckner et al [15]) with a model top at 1 Pa (80 km). It was applied at a spectral resolution of T30, which relates to a rather coarse grid but is enough to capture dynamic effects due to the introduced stratospheric chemistry.…”