Volcanic ash dispersal forecasts are routinely used to avoid aircraft encounters with volcanic ash. However, the accuracy of these forecasts depends on the knowledge of key factors that are usually difficult to observe directly. In this work we apply an inverse methodology to improve ash concentration forecasts. Results are encouraging, showing that accurate estimations of ash emissions can be performed using the proposed approach, leading to an improvement in ash concentration forecasts.

We developed the Real-time On-road Emission (ROE v1.0) model to obtain the street-scale on-road hot emissions by using real-time big data for traffic provided by the Gaode Map navigation application. The results are close to other emission inventories. Meanwhile, we applied our results to a street-level air quality model for studying the impact of the national holiday traffic volume change on air quality. The model can be further extended to more districts in China or other countries.

Uncertain parameters in physical parameterizations of general circulation models (GCMs) greatly impact model performance. In this study, an automated and efficient parameter optimization with the radiation balance constraint is presented and applied in the Community Atmospheric Model. Results show that the synthesized performance under the optimal parameters is 6.3 % better than the control run and the radiation imbalance is as low as 0.1 W m².

We present LAVENDAR, a mathematical method for combining observations with models of the terrestrial environment. Here we use it to improve estimates of crop growth in the UK Met Office land surface model. However, the method is model agnostic, requires no modification to the underlying code and can be applied to any part of the model. In the example application we improve estimates of maize yield by 74 % by assimilating observations of leaf area, crop height and photosynthesis.

We present a new near-global coupled biogeochemical ocean-circulation model configuration of the Southern Ocean. The configuration features both a relatively equilibrated oceanic carbon inventory and an explicit representation of mesoscale eddies. In this paper, we document the model configuration and showcase its potential to tackle research questions such as the Southern Ocean carbon uptake dynamics on decadal timescales.

Sea ice is an important component of the global climate system. The presence of a snow layer covering sea ice can impact ice mass and energy budgets. The detailed, physics-based, multi-layer snow model SNOWPACK was modified to simulate the snow–sea-ice system, providing simulations of the snow microstructure, water percolation and flooding, and superimposed ice formation. The model is applied to in situ measurements from snow and ice mass-balance buoys installed in the Antarctic Weddell Sea.

The Bosphorus exchange is of critical importance for hydrodynamics and hydroclimatology of the Black Sea. In this study, we report on the development of a medium-resolution circulation model of the Black Sea, making use of surface atmospheric forcing with high space and time resolution, climatic river fluxes and strait exchange, enabled by adding elementary details of strait and coastal topography and seasonal hydrology specified in an artificial box on the Marmara Sea side.

When the same weather or climate simulation is run on different high-performance computing (HPC) platforms, model outputs may not be identical for a given initial condition. Here, we investigate the behaviour of the Preindustrial simulation prepared by the UK Met Office for the forthcoming CMIP6 under different computing environments. Discrepancies between the means of key climate variables were analysed at different timescales, from decadal to centennial.

Deep-sea sediment archives are made up of the calcareous tests of foraminifera, small sea dwelling organisms that record the Earth's past climate. Sediment cores retrieved from the sea floor contain sediment that is systematically bioturbated (mixed). The SEAMUS model of single foraminifera sedimentation and bioturbation allows users to quantify the error of bioturbation upon their foraminifera-derived climate reconstructions and radiocarbon dates.

This paper presents the AtChem software, which can be used to build box models for atmospheric chemistry studies. The software is designed to facilitate the use of one of the most important chemical mechanisms used by atmospheric scientists, the Master Chemical Mechanism. AtChem exists in two versions: an on-line application for laboratory studies and educational or outreach activities and an offline version for more complex models and batch simulations. AtChem is open source under MIT License.

Models need to account for forest age structures when investigating land use influences on land–atmosphere feedbacks. We present a consolidated scheme to introduce forest age classes, combining age-dependent simulations of important processes with the possibility to trace forest age, and describe its implementation in JSBACH4, the land surface model of the ICON Earth system model. We evaluate simulations with and without age classes demonstrating the benefit of forest age classes in JSBACH4.

The data request of the Coupled Model Intercomparison Project Phase 6 (CMIP6) defines all the quantities from CMIP6 simulations that should be archived. The building blocks and structure of the CMIP6 Data Request, which has been constructed to meet these challenges, are described in this paper.

The Canadian Hydrological Model (CHM) is a next-generation distributed model. Although designed to be applied generally, it has a focus for application where cold-region processes, such as snowpacks, play a role in hydrology. A key feature is that it uses a multi-scale surface representation, increasing efficiency. It also enables algorithm comparisons in a flexible structure. Model philosophy, design, and several cold-region-specific examples are described.

Wind farms affect local weather and microclimates. These effects can be simulated in weather models, usually by removing momentum at the location of the wind farm. Some debate exists whether additional turbulence should be added to capture the enhanced mixing of wind farms. By comparing simulations to measurements from airborne campaigns near offshore wind farms, we show that additional turbulence is necessary. Without added turbulence, the mixing is underestimated during stable conditions.

GEM–MACH–GHG is a coupled weather and greenhouse gas transport model at Environment and Climate Change Canada. We have developed the regional version of GEM–MACH–GHG, mainly focusing on Canada and the United States, as a follow-up to the global version of GEM–MACH–GHG. The regional model is superior to our global model in terms of weather forecasts and CO₂ simulation.

This paper describes a new satellite simulator. Its purpose is to simulate the CLARA-A2 climate data record from a climate model atmosphere. We explain how the simulator takes into account the regionally variable cloud detection skill of the observations. The simulator makes use of the long/lat-gridded validation between CLARA-A2 and the CALIOP satellite-borne lidar dataset. Using the EC-Earth climate model, we show a sizable impact on climate model validation, especially at high latitudes.

We present CobWeb 1.0, a graphical user interface for analysing tomographic images of geomaterials. CobWeb offers different machine learning techniques for accurate multiphase image segmentation and visualizing material specific parameters such as pore size distribution, relative porosity and volume fraction. We demonstrate a novel approach of dual filtration and dual segmentation to eliminate edge enhancement artefact in synchrotron-tomographic datasets and provide the computational code.

We developed a novel urban ecohydrological model (UT&C v1.0) that is able to account for the effects of different plant types on the urban climate and hydrology, as well as the effects of the urban environment on plant well-being and performance. UT&C performs well when compared against energy flux measurements in three cities in different climates (Singapore, Melbourne, Phoenix) and can be used to assess urban climate mitigation strategies that aim at increasing or changing urban green cover.

This study investigates if ozone source apportionment results using a tagged tracer approach depend on the resolutions of the applied model and/or emission inventory. For this we apply a global to regional atmospheric chemistry model, which allows us to compare the results on global and regional scales. Our results show that differences on the continental scale (e.g. Europe) are rather small (10 %); on the regional scale, however, differences of up to 30 % were found.