The models that are used to describe the atmospheres of Earth and other planets are often very complicated. Although this is necessary for such things as weather prediction, it does not help in understanding. Furthermore, when studying other planets, there are insufficient data to warrant the use of complicated models. We have developed a framework that allows the construction of models of appropriate complexity for the problem at hand, and thus helps to actually model these atmospheres.

This paper presents a simple vegetation model for use as part of a climate or Earth system model. The model equations and their derivations are presented. We evaluate the model’s performance offline using near-present-day real-world datasets and deem it to be satisfactory. The model is useful because it is fast, easy to understand, and general in its formulations. It was developed to better simulate climate–vegetation feedbacks for answering paleoclimate research questions.

We developed an autocalibration software for the hydrodynamic-ecological lake model DYRESM-CAEDYM with a massive number of water quality parameters, using a Monte Carlo sampling method, in order to reduce time-consuming iterative simulations with empirical judgements and find optimal model parameter set. The successful applications to Lake Rotorua suggest this software is much more efficient than traditional methods and of wide applicability to other water quality models.

To describe coasts in a computer model, many processes have to be represented, from the air to the water to the ocean floor, from different scientific disciplines. No existing computer model adequately addresses this complexity. We present the Modular System for Shelves and Coasts (MOSSCO), which embraces this diversity and flexibly connects several tens of individual process models. MOSSCO also makes it easier to bring local knowledge to the Earth system level.

Global models generally oversimplify the representation of soil organic carbon (SOC), and thus its response to global warming remains uncertain. We present the new soil module ORCHIDEE-SOM, within the global model ORCHIDEE, that refines the representation of SOC dynamics and includes the dissolved organic carbon (DOC) processes. The model is able to reproduce SOC stocks and DOC concentrations in four different ecosystems, opening an opportunity for improved predictions of SOC in global models.

We evaluate global tropospheric NO₂ simulations using a chemical transport model (CTM) at horizontal resolutions of 0.56, 1.1, and 2.8°. Agreement against satellite retrievals improved greatly at 0.56 and 1.1° resolutions (compared to 2.8°) over polluted and biomass burning regions, especially over areas with strong local sources, such as a megacity. The evaluations demonstrate the potential of using a high-resolution global CTM for studying megacity-scale air pollutants across the entire globe.

More than 1 billion tons of mineral dust particles are raised into the atmosphere every year, which has a significant impact on climate, society and ecosystems. The location, time and amount of dust emissions depend on surface and wind conditions. In the atmospheric chemistry–climate model EMAC, we have updated the relevant surface data and equations. Our validation shows that the updates substantially improve the agreement of model results and observations.

This paper documents the numerical experiments to be used in phase 1 of the Stratosphere–troposphere Processes And their Role in Climate (SPARC) Quasi-Biennial Oscillation initiative (QBOi), which was set up to improve the representation of the QBO and tropical stratospheric variability in global climate models.

The Paleoclimate Modelling Intercomparison Project (PMIP) takes advantage of the existence of past climate states radically different from the recent past to test climate models used for climate projections and to better understand these climates. This paper describes the PMIP contribution to CMIP6 (Coupled Model Intercomparison Project, 6th phase) and possible analyses based on PMIP results, as well as on other CMIP6 projects.

As part of the model documentation of the MECO(n) system, this article documents the basics of the Multi-Model-Driver expansion (MMD v2.0) to two-way coupling and the newly developed generic MESSy submodel GRID (v1.0), which is used by MMD v2.0 for the generalised definition of arbitrary grids and for the transformation of data between them.

This hydrologic emulator provides researchers with an easy way to investigate the variations in water budgets at any spatial scale of interest, with minimum requirements of effort, reasonable model predictability, and appealing computational efficiency. We expect it to have a profound influence on scientific endeavors in hydrological modeling and to excite the immediate interest of researchers working on climate impact assessments, uncertainty/sensitivity analysis, and integrated assessment.

To reduce computational costs, ECCC's new method to calculate the UV Index involves scaling and weighting the irradiance contribution of four low-res UV broadbands currently produced by the GEM forecast model. A high-res irradiance spectrum was produced using Cloud-J to create simulated GEM broadbands to calibrate the original GEM broadbands. The scaled GEM broadbands are then weighted accordingly so that the resultant UV Index field emulates the high-res UV Index field calculated from Cloud-J.

Ozone depletion events (ODEs) in the polar boundary layer are observed frequently in spring. ODEs serve as a source of tropospheric BrO at high latitudes. A treatment of bromine release and recycling on sea-ice- and snow-covered surfaces is implemented in global chemistry–climate model EMAC based on a scheme of Toyota et al. (2011). Many aspects of bromine enhancement and associated ODEs are reproduced in both polar regions. Further bromine release mechanisms can now be tested in a global model.

There is little consensus on the impacts and efficacy of proposed carbon dioxide removal (CDR) methods as a potential means of mitigating climate change. To address this need, the Carbon Dioxide Removal Model Intercomparison Project (or CDR-MIP) has been initiated. This project brings together models of the Earth system in a common framework to explore the potential, impacts, and challenges of CDR. Here, we describe the first set of CDR-MIP experiments.

The discontinuous Galerkin (DG) finite element method is well suited for the modelling of three-dimensional flows exhibiting strong density gradients. Here, a vertical adaptive mesh method is developed for DG finite element methods and implemented into SLIM 3D. This technique increases drastically the accuracy of simulations including strong stratification, without affecting the simulation cost. SLIM 3D is then used to simulate the thermocline oscillations of Lake Tanganyika.

We present a concept to prove that a parametric model is well calibrated, i.e., that changes of its free parameters cannot lead to a much better model–data misfit anymore. The intention is motivated by the fact that calibrating global biogeochemical ocean models is important for assessment and inter-model comparison but computationally expensive.

Methane is an important greenhouse gas and methane emissions from wetlands contribute to the warming of the climate. Wetland methane emissions are also challenging to estimate. We analyze the performance of a new wetland emission computer model utilizing mathematical methods and using data from a wetland in southern Finland. The analysis helps to explain how wetlands produce methane and how emission modeling can be improved and uncertainties in the emission estimates reduced in future studies.