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Journal ArticleDOI

Atmospheric component of the MPI-M Earth System Model: ECHAM6

TL;DR: ECHAM6, the sixth generation of the atmospheric general circulation model ECHAM, is described in this article, which represents the present climate as well as, or better than, its predecessor.
Abstract: [1] ECHAM6, the sixth generation of the atmospheric general circulation model ECHAM, is described. Major changes with respect to its predecessor affect the representation of shortwave radiative transfer, the height of the model top. Minor changes have been made to model tuning and convective triggering. Several model configurations, differing in horizontal and vertical resolution, are compared. As horizontal resolution is increased beyond T63, the simulated climate improves but changes are incremental; major biases appear to be limited by the parameterization of small-scale physical processes, such as clouds and convection. Higher vertical resolution in the middle atmosphere leads to a systematic reduction in temperature biases in the upper troposphere, and a better representation of the middle atmosphere and its modes of variability. ECHAM6 represents the present climate as well as, or better than, its predecessor. The most marked improvements are evident in the circulation of the extratropics. ECHAM6 continues to have a good representation of tropical variability. A number of biases, however, remain. These include a poor representation of low-level clouds, systematic shifts in major precipitation features, biases in the partitioning of precipitation between land and sea (particularly in the tropics), and midlatitude jets that appear to be insufficiently poleward. The response of ECHAM6 to increasing concentrations of greenhouse gases is similar to that of ECHAM5. The equilibrium climate sensitivity of the mixed-resolution (T63L95) configuration is between 2.9 and 3.4 K and is somewhat larger for the 47 level model. Cloud feedbacks and adjustments contribute positively to warming from increasing greenhouse gases.

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Citations
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Journal ArticleDOI
TL;DR: In this article, the Max-Planck-Institute Earth System Model (MPI-ESM) is used in the Coupled Model Intercomparison Project phase 5 (CMIP5) in a series of climate change experiments for either idealized CO2-only forcing or forcings based on observations and the Representative Concentration Pathway (RCP) scenarios.
Abstract: [1] The new Max-Planck-Institute Earth System Model (MPI-ESM) is used in the Coupled Model Intercomparison Project phase 5 (CMIP5) in a series of climate change experiments for either idealized CO2-only forcing or forcings based on observations and the Representative Concentration Pathway (RCP) scenarios. The paper gives an overview of the model configurations, experiments related forcings, and initialization procedures and presents results for the simulated changes in climate and carbon cycle. It is found that the climate feedback depends on the global warming and possibly the forcing history. The global warming from climatological 1850 conditions to 2080–2100 ranges from 1.5°C under the RCP2.6 scenario to 4.4°C under the RCP8.5 scenario. Over this range, the patterns of temperature and precipitation change are nearly independent of the global warming. The model shows a tendency to reduce the ocean heat uptake efficiency toward a warmer climate, and hence acceleration in warming in the later years. The precipitation sensitivity can be as high as 2.5% K−1 if the CO2 concentration is constant, or as small as 1.6% K−1, if the CO2 concentration is increasing. The oceanic uptake of anthropogenic carbon increases over time in all scenarios, being smallest in the experiment forced by RCP2.6 and largest in that for RCP8.5. The land also serves as a net carbon sink in all scenarios, predominantly in boreal regions. The strong tropical carbon sources found in the RCP2.6 and RCP8.5 experiments are almost absent in the RCP4.5 experiment, which can be explained by reforestation in the RCP4.5 scenario.

1,344 citations

Journal ArticleDOI
TL;DR: In this paper, a non-hydrostatic dynamical core is developed for the ICOsahedral Non-Hydrostatic (ICON) modeling framework, which is a joint project of the German Weather Service (DWD) and the Max Planck Institute for Meteorology (MPI-M).
Abstract: This article describes the non-hydrostatic dynamical core developed for the ICOsahedral Non-hydrostatic (ICON) modelling framework. ICON is a joint project of the German Weather Service (DWD) and the Max Planck Institute for Meteorology (MPI-M), targeting a unified modelling system for global numerical weather prediction (NWP) and climate modelling. Compared with the existing models at both institutions, the main achievements of ICON are exact local mass conservation, mass-consistent tracer transport, a flexible grid nesting capability and the use of non-hydrostatic equations on global domains. The dynamical core is formulated on an icosahedral-triangular Arakawa C grid. Achieving mass conservation is facilitated by a flux-form continuity equation with density as the prognostic variable. Time integration is performed with a two-time-level predictor–corrector scheme that is fully explicit, except for the terms describing vertical sound-wave propagation. To achieve competitive computational efficiency, time splitting is applied between the dynamical core on the one hand and tracer advection, physics parametrizations and horizontal diffusion on the other hand. A sequence of tests with varying complexity indicates that the ICON dynamical core combines high numerical stability over steep mountain slopes with good accuracy and reasonably low diffusivity. Preliminary NWP test suites initialized with interpolated analysis data reveal that the ICON modelling system already achieves better skill scores than its predecessor at DWD, the operational hydrostatic Global Model Europe (GME), and at the same time requires significantly fewer computational resources.

577 citations


Cites background from "Atmospheric component of the MPI-M ..."

  • ...The main goals formulated in the initial phase of the collaboration were as follows: • better conservation properties than in the existing global models GME (Majewski et al., 2002) and ECHAM (Stevens et al., 2013), with the obligatory requirements of exact local mass conservation and mass-consistent tracer transport and the additional wish to achieve energy conservation; • better scalability on future massively parallel highperformance computing architectures; and • the availability of some means of static mesh refinement, which was subsequently concretized into the capability of mixing one-way nested and two-way nested grids within one model application, combined with an option for vertical nesting in order to allow the global grid to extend into the mesosphere (which greatly facilitates the assimilation of satellite data), whereas the nested domains extend only into the lower stratosphere in order to save computing time....

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  • ...…phase of the collaboration were as follows: • better conservation properties than in the existing global models GME (Majewski et al., 2002) and ECHAM (Stevens et al., 2013), with the obligatory requirements of exact local mass conservation and mass-consistent tracer transport and the additional…...

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  • ..., 2002) and ECHAM (Stevens et al., 2013), with the obligatory requirements of exact local mass conservation and mass-consistent tracer transport and the additional wish to achieve energy conservation; • better scalability on future massively parallel highperformance computing architectures; and • the availability of some means of static mesh refinement, which was subsequently concretized into the capability of mixing one-way nested and two-way nested grids within one model application, combined with an option for vertical nesting in order to allow the global grid to extend into the mesosphere (which greatly facilitates the assimilation of satellite data), whereas the nested domains extend only into the lower stratosphere in order to save computing time....

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Journal ArticleDOI
TL;DR: The model has a climate sensitivity to a doubling of CO2 over preindustrial conditions of 2.77 K, maintaining the previously identified highly nonlinear global mean response to increasing CO2 forcing, which nonetheless can be represented by a simple two‐layer model.
Abstract: A new release of the Max Planck Institute for Meteorology Earth System Model version 1.2 (MPI‐ESM1.2) is presented. The development focused on correcting errors in and improving the physical processes representation, as well as improving the computational performance, versatility, and overall user friendliness. In addition to new radiation and aerosol parameterizations of the atmosphere, several relatively large, but partly compensating, coding errors in the model's cloud, convection, and turbulence parameterizations were corrected. The representation of land processes was refined by introducing a multilayer soil hydrology scheme, extending the land biogeochemistry to include the nitrogen cycle, replacing the soil and litter decomposition model and improving the representation of wildfires. The ocean biogeochemistry now represents cyanobacteria prognostically in order to capture the response of nitrogen fixation to changing climate conditions and further includes improved detritus settling and numerous other refinements. As something new, in addition to limiting drift and minimizing certain biases, the instrumental record warming was explicitly taken into account during the tuning process. To this end, a very high climate sensitivity of around 7 K caused by low‐level clouds in the tropics as found in an intermediate model version was addressed, as it was not deemed possible to match observed warming otherwise. As a result, the model has a climate sensitivity to a doubling of CO2 over preindustrial conditions of 2.77 K, maintaining the previously identified highly nonlinear global mean response to increasing CO2 forcing, which nonetheless can be represented by a simple two‐layer model.

542 citations


Cites background or methods from "Atmospheric component of the MPI-M ..."

  • ...1 were required because of inconsistent formulations in the convection scheme, in the grid-scale stratiform cloud condensation scheme, and in the turbulence transfer scheme, causing violations of the atmospheric energy budget (Stevens et al., 2013)....

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  • ...For a detailed description of ECHAM6, see Stevens et al. (2013)....

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  • ...…the last release in the series of coupled climate models based on the HOPE, later renamed to MPIOM, ocean models (Maier-Reimer et al., 1982) and the ECHAM spectral dynamical core atmosphere models (Roeckner et al., 1989); see Stevens et al. (2013) for a historical overview of ECHAM model versions....

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  • ...1 (Stevens et al., 2013)....

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  • ...3, an attempt is made to improve the low-bias simulation of marine stratocumulus (Stevens et al., 2013, Figure 5) by introducing a parameterization of vertical subgrid scale cloudiness such that fcld = 1 is achieved already at a relative humidity 𝜂 1....

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Journal ArticleDOI
TL;DR: In this paper, the magnitude and evolution of parameters that characterize feedbacks in the coupled carbon-climate system are compared across nine Earth system models (ESMs), based on results from biogeochemically, radiatively, and fully coupled simulations in which CO2 increases at a rate of 1% yr−1.
Abstract: The magnitude and evolution of parameters that characterize feedbacks in the coupled carbon–climate system are compared across nine Earth system models (ESMs). The analysis is based on results from biogeochemically, radiatively, and fully coupled simulations in which CO2 increases at a rate of 1% yr−1. These simulations are part of phase 5 of the Coupled Model Intercomparison Project (CMIP5). The CO2 fluxes between the atmosphere and underlying land and ocean respond to changes in atmospheric CO2 concentration and to changes in temperature and other climate variables. The carbon–concentration and carbon–climate feedback parameters characterize the response of the CO2 flux between the atmosphere and the underlying surface to these changes. Feedback parameters are calculated using two different approaches. The two approaches are equivalent and either may be used to calculate the contribution of the feedback terms to diagnosed cumulative emissions. The contribution of carbon–concentration feedback to...

515 citations


Cites background from "Atmospheric component of the MPI-M ..."

  • ..., consists of a general circulation model for the atmosphere (ECHAM6) (Stevens et al. 2013; Roeckner et al. 2003) at T63 (1.98 3 1.98) resolution with 47 vertical levels and the oceanic model MPI-OM with a nominal horizontal resolution of approximately 1.58 and 40 vertical layers (Jungclaus et…...

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  • ..., consists of a general circulation model for the atmosphere (ECHAM6) (Stevens et al. 2013; Roeckner et al. 2003) at T63 (1.98 3 1.98) resolution with 47 vertical levels and the oceanic model MPI-OM with a nominal horizontal resolution of approximately 1.58 and 40 vertical layers (Jungclaus et al. 2013, 2006)....

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Journal ArticleDOI
TL;DR: In this paper, the performance of the ocean/sea-ice model MPIOM, coupled to a new version of the atmosphere model ECHAM6 and modules for land surface and ocean biogeochemistry, is assessed for two model versions with different grid resolution in the ocean.
Abstract: [1] MPI-ESM is a new version of the global Earth system model developed at the Max Planck Institute for Meteorology. This paper describes the ocean state and circulation as well as basic aspects of variability in simulations contributing to the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The performance of the ocean/sea-ice model MPIOM, coupled to a new version of the atmosphere model ECHAM6 and modules for land surface and ocean biogeochemistry, is assessed for two model versions with different grid resolution in the ocean. The low-resolution configuration has a nominal resolution of 1.5°, whereas the higher resolution version features a quasiuniform, eddy-permitting global resolution of 0.4°. The paper focuses on important oceanic features, such as surface temperature and salinity, water mass distribution, large-scale circulation, and heat and freshwater transports. In general, these integral quantities are simulated well in comparison with observational estimates, and improvements in comparison with the predecessor system are documented; for example, for tropical variability and sea ice representation. Introducing an eddy-permitting grid configuration in the ocean leads to improvements, in particular, in the representation of interior water mass properties in the Atlantic and in the representation of important ocean currents, such as the Agulhas and Equatorial current systems. In general, however, there are more similarities than differences between the two grid configurations, and several shortcomings, known from earlier versions of the coupled model, prevail.

507 citations

References
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Journal ArticleDOI
TL;DR: ERA-Interim as discussed by the authors is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), which will extend back to the early part of the twentieth century.
Abstract: ERA-Interim is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). The ERA-Interim project was conducted in part to prepare for a new atmospheric reanalysis to replace ERA-40, which will extend back to the early part of the twentieth century. This article describes the forecast model, data assimilation method, and input datasets used to produce ERA-Interim, and discusses the performance of the system. Special emphasis is placed on various difficulties encountered in the production of ERA-40, including the representation of the hydrological cycle, the quality of the stratospheric circulation, and the consistency in time of the reanalysed fields. We provide evidence for substantial improvements in each of these aspects. We also identify areas where further work is needed and describe opportunities and objectives for future reanalysis projects at ECMWF. Copyright © 2011 Royal Meteorological Society

22,055 citations


"Atmospheric component of the MPI-M ..." refers result in this paper

  • ...This is evident in Figure 14, which compares the solstice season sea-level pressure biases relative to the ERA-Interim reanalysis [Dee et al., 2011] for ECHAM5, and for the LR and HR configurations of ECHAM6....

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Journal ArticleDOI
TL;DR: The fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance the authors' knowledge of climate variability and climate change.
Abstract: The fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance our knowledge of climate variability and climate change. Researchers worldwide are analyzing the model output and will produce results likely to underlie the forthcoming Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Unprecedented in scale and attracting interest from all major climate modeling groups, CMIP5 includes “long term” simulations of twentieth-century climate and projections for the twenty-first century and beyond. Conventional atmosphere–ocean global climate models and Earth system models of intermediate complexity are for the first time being joined by more recently developed Earth system models under an experiment design that allows both types of models to be compared to observations on an equal footing. Besides the longterm experiments, CMIP5 calls for an entirely new suite of “near term” simulations focusing on recent decades...

12,384 citations


"Atmospheric component of the MPI-M ..." refers methods in this paper

  • ...Moist Convection [20] The parameterization of moist cumulus convection is based on the mass-flux framework developed by Tiedtke [1989], with the representation of deep convection incorporating the changes introduced by Nordeng [1994]....

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Journal ArticleDOI
TL;DR: In this article, a diagram has been devised that can provide a concise statistical summary of how well patterns match each other in terms of their correlation, their root-mean-square difference, and the ratio of their variances.
Abstract: A diagram has been devised that can provide a concise statistical summary of how well patterns match each other in terms of their correlation, their root-mean-square difference, and the ratio of their variances. Although the form of this diagram is general, it is especially useful in evaluating complex models, such as those used to study geophysical phenomena. Examples are given showing that the diagram can be used to summarize the relative merits of a collection of different models or to track changes in performance of a model as it is modified. Methods are suggested for indicating on these diagrams the statistical significance of apparent differences and the degree to which observational uncertainty and unforced internal variability limit the expected agreement between model-simulated and observed behaviors. The geometric relationship between the statistics plotted on the diagram also provides some guidance for devising skill scores that appropriately weight among the various measures of pattern correspondence.

5,762 citations


"Atmospheric component of the MPI-M ..." refers background or methods in this paper

  • ...Given changes in electronic publishing, such reports are becoming increasingly less accessible, and less acceptable, all the more so with the rise of coordinated projects such as the coupled model intercomparison project (presently phase 5, or CMIP5, Taylor et al. [2012]), for which model output is widely used by those not active in the model development....

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  • ...[43] In the course of evaluating the MPI-ESM and ECHAM6 simulations as part of CMIP5, a number of bugs have been identified which impact simulations....

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  • ...To construct this diagram, the areaweighted root-mean-square difference between the annual climatology of ECHAM and CERES is decomposed by the amplitude and correlation between ECHAM and CERES (the reference) [Taylor, 2001]....

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Journal ArticleDOI
TL;DR: The Global Precipitation Climatology Project (GPCP) version 2 Monthly Precise Analysis as discussed by the authors is a merged analysis that incorporates precipitation estimates from low-orbit satellite microwave data, geosynchronous-orbit-satellite infrared data, and rain gauge observations.
Abstract: The Global Precipitation Climatology Project (GPCP) Version 2 Monthly Precipitation Analysis is described. This globally complete, monthly analysis of surface precipitation at 2.5 degrees x 2.5 degrees latitude-longitude resolution is available from January 1979 to the present. It is a merged analysis that incorporates precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit-satellite infrared data, and rain gauge observations. The merging approach utilizes the higher accuracy of the low-orbit microwave observations to calibrate, or adjust, the more frequent geosynchronous infrared observations. The data set is extended back into the premicrowave era (before 1987) by using infrared-only observations calibrated to the microwave-based analysis of the later years. The combined satellite-based product is adjusted by the raingauge analysis. This monthly analysis is the foundation for the GPCP suite of products including those at finer temporal resolution, satellite estimate, and error estimates for each field. The 23-year GPCP climatology is characterized, along with time and space variations of precipitation.

4,951 citations

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