Response of the middle atmosphere to anthropogenic and natural forcings in the CMIP5 simulations with the Max Planck Institute Earth system model

Abstract

[1] The ECHAM6 atmospheric general circulation model is the atmosphere component of the Max Planck Institute Earth System Model (MPI-ESM) that is used in the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations. As ECHAM6 has its uppermost layer centered at 0.01 hPa in the upper mesosphere, these simulations offer the opportunity to study the middle atmosphere climate change and its relation to the troposphere on the basis of a very comprehensive set of state-of-the-art model simulations. The goals of this paper are (a) to introduce those new features of ECHAM6 particularly relevant for the middle atmosphere, including external forcing data, and (b) to evaluate the simulated middle atmosphere and describe the simulated response to natural and anthropogenic forcings. New features in ECHAM6 with respect to ECHAM5 include a new short-wave radiation scheme, the option to vary spectral irradiance independent of total solar irradiance, and a latitude-dependent gravity-wave source strength. The description of external forcing data focuses on solar irradiance and ozone. Stratospheric temperature trends simulated with the MPI-ESM for the last decades of the 20th century agree well with observations. The future projections depend strongly on the scenario. Under the high emission scenario RCP8.5, simulated temperatures are locally lower by more than 20 K than preindustrial values. Many of the simulated patterns of the responses to natural forcings as provided by solar variability, volcanic aerosols, and El Niño-Southern Oscillation, largely agree with the observations.

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

“…Numerical diffusion is reduced when increasing the vertical resolution (see Land et al, 2002 for an applied and Quarteroni et al, 2010 for an theoretical approach), resulting in lower vertical extent of the sulfate layer. Schmidt et al (2013) show that differences between the atmospheric mean states and trends simulated with two different vertical resolutions of ECHAM are in general small except for the tropics where the QBO is a dominant feature. Thus, we presume that we can assign differences between responses to sulfate aerosol forcing simulated with different vertical resolutions mostly to the internally generated or not generated QBO and to different strength of vertical numerical diffusion.…”

Overview of experiment design and comparison of models participating in phase 1 of the SPARC Quasi-Biennial Oscillation initiative (QBOi)

“…For IFS43r1, the use of the Scinocca (2003) scheme to generate a QBO is described in Orr et al (2010). For MPI-ESM-MR, the use of the Hines (1997a, b) scheme is described in Schmidt et al (2013). The abbreviation in square brackets for each scheme (second column;…”

Numerical studies on the Impact of the Last Glacial Cycle on recent borehole temperature profiles: implications for terrestrial energy balance

“…(e.g., Schmidt et al, 2013;Phipps et al, 2013;Fernández-Donado et al, 2013;Coats et al, 2013). With regard to the latter, the abundance of paleoclimate data during this period provides numerous estimates of past climatic conditions against which GCMs can be tested (Jansen et al, 2007;Randall et al, 2007;González-Rouco et al, 2009).…”