Simple climate models play an integral role in policy and scientific communities. Hector v1.0 is an open-source, object-oriented, simple global climate carbon-cycle model. Hector reproduces the global historical trends of atmospheric [CO2], radiative forcing, and surface temperatures. Hector simulates all four representative concentration pathways with equivalent rates of change of key variables over time compared to current observations and other models.

We evaluate the predictive performance of a 12-month, 12km horizontal resolution WRF-Chem air quality model simulation for the contiguous United States. Model performance is comparable to other contemporary models used for regulatory and health-effects analysis, with 12% bias for daytime ozone and -1% bias for fine particulate matter (PM2.5). Performance for PM2.5 is worse in winter and in the western U.S. than in other seasons and regions, suggesting opportunities for future model development.

We describe modules for atmospheric chemistry, wet and dry deposition and lightning NO production, which have been newly introduced in ECMWF's weather forecasting model. With that model, we want to forecast global air pollution as part of the European Copernicus Atmosphere Monitoring Service. We show that the new model results compare as well or better with in situ and satellite observations of ozone, CO, NO2, SO2 and formaldehyde as the previous model.

This paper accompanies the first release of libmpdata++, a C++ library implementing the multidimensional positive-definite advection transport algorithm (MPDATA) on a regular structured grid. The library offers basic numerical solvers for systems of generalised transport equations. All solvers offer parallelisation through domain decomposition using shared-memory parallelisation. The paper describes the library programming interface, and serves as a user guide.

Farming is using more of the land surface terrestrial ground and this expansion exerts an increasing impact on the terrestrial carbon cycle. In order to understand the impact of such processes, we calibrate the parametric models within CLM-Crop (part of the Community Land Model (CLM)). The agreement between AmeriFlux observations and model projections is greatly improved for soybean, which is the focus of this study.

Because global climate models (GCMs) are typically run at coarse spatial resolution, lakes are often poorly resolved in their global fields. When downscaling such GCMs using the Weather Research & Forecasting (WRF) model, use of WRF’s default interpolation methods can result in unrealistic lake temperatures and ice cover, which can impact simulated air temperatures and precipitation. Here, alternative methods for setting lake variables in WRF downscaling applications are presented and compared.

This study evaluates the capability of five vegetation models to simulate the response of forest productivity to changes in temperature and drought, using data collected from an Amazonian forest. This study concludes that model consistencies in the responses of net canopy carbon production to temperature and precipitation change were the result of inconsistently modelled leaf-scale process responses and substantial variation in modelled leaf area responses.

The article presents MODES, a new software for the analysis of properties of balanced and inertio-gravity circulations across many scales in (re)analyses, weather forecasts and climate models. The software and real-time results based on ECMWF model can be found at http://meteo.fmf.uni-lj.si/MODES. Evaluation of models' ability to reproduce the unbalanced tropical circulation is expected to provide new insights on model performance that is helpful to diagnose deficiencies and define improvements.

In this manuscript, we discuss the development and validation of a new momentum balance solver for modeling the flow of glaciers and ice sheets based on the 1st-order Stokes equations. We demonstrate the numerical convergence of our solver (with respect to computational mesh spacing), its flexibility (with respect to both the choice of mesh and finite element type), and its computational performance (robustness and scalability when applied to both idealized and realistic ice sheet simulations).

This paper describes an analysis of the software architecture of global climate models. The analysis provides a visualization of the structure of these models, and reveals interesting differences between the models developed at different research labs.

Irrigation agriculture is required to sustain yields that allow feeding the world population. A robust assessment of irrigation requirement (IRR) relies on a sound quantification of evapotranspiration (ET). We prepared a multi-model ensemble considering several ET methods and investigate uncertainties in simulating IRR. More generally, we provide an example of the value of investigating the uncertainty in models that may be used to inform policy-making and to elaborate best management practices.

This paper presents the tangent and adjoint models for the NEMO ocean modelling framework. They are useful tools for sensitivity and stability analysis. The implementation choices and the validation of the code is presented as well as a selection of applications.

The paper presents a statistical method (shrinkage) that can be used to estimate rough emission fields, e.g., fossil fuel CO2 emissions, from measurements of concentrations. This method is demonstrated in a test case where the emissions are modeled using wavelets. We find that the method can eliminate unnecessary complexity from the wavelet model, ensures non-negativity of the emissions, is computationally efficient and is, by construction, insensitive to prior guesses of the total emission.