LIM3.6 presented in this paper is the last release of the Louvain-la-Neuve sea ice model, and will be used for the next climate model intercomparison project (CMIP6). The model's robustness, versatility and sophistication have been improved.

Current land surface models (LSMs) poorly represent irrigation impacts on regional hydrology. Approaches to include irrigation in LSMs are based on either potentially outdated irrigation inventory data or soil moisture curves that are not constrained by regional water balances. We use satellite remote sensing of actual ET and groundwater depletion to develop recent estimates of regional irrigation data. Remote sensing parameterizations of irrigation improve model performance.

This paper investigates the impacts of uncertainties in the climate, the vegetation dynamic, the soil properties and the cropland management on the simulation of evapotranspiration from the ISBA-A-gs land surface model over a 12-year Mediterranean crop succession. It mainly shows that errors in the soil parameters and the lack of irrigation in the simulation have the largest influence on evapotranspiration compared to the uncertainties in the climate and the vegetation dynamic.

We report a soil COS flux model that is the first to resolve both vertical transport and microbial sources and sinks in soil and litter. By evaluation with field data, we show that the model can reproduce observed daily and long-term variations of soil COS flux. We also demonstrate that diffusion is important in controlling the flux, by limiting the COS available for soil uptake when there is strong litter uptake and modulating the water content dependence of soil uptake.

The ECCO v4 non-linear inverse modeling framework and its reference solution are made publicly available. The inverse estimate of ocean physics and atmospheric forcing yields a dynamically consistent and global state estimate without unidentified sources of heat and salt that closely fits in situ and satellite data. Any user can reproduce it accurately. Parametric and external model uncertainties are of comparable magnitudes and generally exceed structural model uncertainties.

The formation of cold air pools in valleys under stable conditions represents an important challenge for numerical weather prediction (NWP). In this study a two-month cold pool simulation is presented using a high-resolution NWP model. Results are compared to observations and assumptions made in the cloud parametrization scheme about the sub-grid variability of humidity are shown to dominate model bias. Our results show that this is a key area for very high resolution modelling development.

Most ocean models, including NEMO, have unrealistic Southern Ocean deep convection. That is, through extensive areas of the Southern Ocean, they exhibit convection from the surface of the ocean to the sea floor. We find this convection to be an issue as it impacts the whole ocean circulation, notably strengthening the Antarctic Circumpolar Current. Using sensitivity experiments, we show that counter-intuitively the vertical mixing needs to be enhanced to reduce this spurious convection.

The design of the icosahedral atmospheric dynamical core DYNAMICO is presented. The key contribution is to combine a strict separatation of kinematics from dynamics to a Hamiltonian formulation of the equations of motion in a non-Eulerian vertical coordinate to achieve energetic consistency. This approach allows for a unified treatment of various equations of motion: multi-layer shallow-water equations and hydrostatic primitive equations.

A detailed chemical mechanism including 205 reactions is developed for use in the Master Chemical Mechanism. With this new chlorine mechanism, it was found that the nocturnal formation of ClNO2 has high potential to perturb the next day's atmospheric photochemistry, by enhancing the radical production and cycling, VOC oxidation and O3 formation, in the polluted coastal environments.

Our relatively shallow shelf seas are warmed at the surface in spring and summer, while strong tidal currents act to mix away the surface warmth. These competing effects strongly influence the conditions for seasonal growth of the phytoplankton that support marine food webs. We have developed a versatile framework for fast computer modelling of shelf seas, to explore seasonal and year-to-year variations of warming and plankton productivity, tested against observations in different regions.

This paper introduces a new inversion framework for N2O using GEOS-Chem and its adjoint, which we employed in a series of observing system simulation experiments to evaluate the source and sink constraints provided by surface and aircraft-based N2O measurements. We also applied a new approach for estimating a posteriori uncertainty for high-dimensional inversions, and used it to quantify the spatial and temporal resolution of N2O emission constraints achieved with the current observing network.

A long-term challenge for any model of complex large-scale processes is accounting for the impact of unresolved sub-grid (SG) processes. We quantify the impact of SG mass-balance and ice fluxes on glacial cycle ensemble results for North America. We find no easy solutions to accurately capture these impacts. We show that SG process representation and associated parametric uncertainties can have significant impact on coarse resolution model results for glacial cycle ice sheet evolution.

The contribution of lulcc is to provide a free and open-source framework for land use change modelling. The software, which is provided as an R package, addresses problems associated with the current paradigm of closed-source, specialised land use change modelling software which disrupt the scientific process. It is an attempt to move the discipline towards open and transparent science and to ensure land use change models are accessible to scientists working across the geosciences.

Semi-parameterised street canyon models are popular due to their speed and low input requirements. One often-used assumption is that emissions are homogeneously distributed in the entire length and width of the street. It is thus the aim of the present study to analyse the impact of this assumption by implementing an inhomogeneous emission geometry scheme and validating it. The results show an improved performance, however, confounded by challenges in estimating the emissions accurately.

In this study, the non-iteration dimensional-split semi-Lagrangian (NDSL) advection scheme is applied to the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) to alleviate the Gibbs phenomenon. The model runs for the Fukushima accident case study suggest that the NDSL can successfully advect radioactive tracers (iodine-131 and cesium-137) without noise from the Gibbs phenomenon.

The performance of the SimSphere SVAT model was comprehensively validated against in situ measurements from selected US and Australian sites of the FLUXNET monitoring network for 2011. The results obtained confirmed the correspondence of the model structure to the real conditions for which it was parameterised, evidencing its ability to reproduce outputs akin to the in situ reference data.To our knowledge this is the first comprehensive validation of SimSphere for Australia and the USA.

We tune the CH4-related parameters of the Community Land Model (CLM) using surrogate global optimization in order to reduce the discrepancies between the CLM predictions and observed CH4 emissions. This is the first application of a surrogate optimization method to calibrate a global climate model. We found that the observation data drives the model to predict more CH4 emissions in the northern latitudes and less in the tropics.

Par@Graph, a software toolbox to reconstruct and analyze large-scale complex climate networks. It exposes parallelism on distributed-memory computing platforms to enable the construction of massive networks from large number of time series based on the calculation of common statistical similarity measures between them. Providing additionally parallel graph algorithms to enable fast calculation of important and common properties of the generated networks on SMP machines.

This technical paper presents a new tool to simulate reactive transport processes in subsurface systems and which couples the open-source software packages OpenGeoSys and IPhreeqc. A flexible parallelization scheme was developed and implemented to enable an optimized allocation of computer resources. The performance tests of the coupling interface and parallelization scheme illustrate the promising efficiency of this generally valid approach to simulate reactive transport problems.

CranSLIK is a model that predicts the movement and spread of a surface oil spill at sea via a statistical approach that takes into account the random, and hence unpredictable, nature, of the affecting parameters. CranSLIK v2.0 demonstrated significant forecasting improvements by capturing the oil spill accurately in real oil spill validation cases and also proved capable of simulating a broader range of oil spill scenarios, while maintaining the run-time efficiency of the method.

The influence of the large grid aspect ratio of horizontal to vertical grid spacing traditionally used in meteorological large-eddy simulations on simulated turbulence is investigated with a series of sensitivity tests with various grid configurations. We confirmed that the grid aspect ratio should be taken into account in the sub-grid scale model to reproduce the theoretical energy spectrum. We also found that the grid aspect ratio has an influence on the turbulent statistics.

A new anisotropic hr-adaptive mesh technique has been applied to modelling of multiscale transport phenomena. Over existing air quality models typically based on static-structured grids using a locally nesting technique, the advantage of the anisotropic hr-adaptive model has the ability to adapt the mesh according to the evolving pollutant distribution and flow features. To illustrate its capability, comparisons have been made between the results obtained using adaptive and uniform meshes.

Recent climate warming causing ice retreat exposes new terrestrial ecosystems that have potentially significant yet largely unexplored roles on large-scale biogeochemical cycling and climate. SHIMMER (Soil biogeocHemIcal Model for Microbial Ecosystem Response) is a new numerical model designed to simulate microbial community establishment and elemental cycling (C, N and P) during initial soil formation in exposed glacier forefields. It is also transferable to other extreme ecosystem types.

This article applies Schwarz-Christoffel (SC) conformal mappings for single-connected and multiple-connected regions to the generation of general orthogonal grids for OGCMs, to achieve 1) the enlarged lat-lon proportion, 2) the removal of landmass and easier load balancing, 3) better spatial resolution on continental boundaries, and 4) alignment of grid lines to large-scale coastlines. The generated grids could be readily utilized by the majority of OGCMs that support general orthogonal grids.