A new aerosol treatment is described and tested in a global climate model. With updated emissions, aerosol chemistry, and microphysics compared to its predecessor, black carbon (BC) mass concentrations aloft better fit observations, surface concentrations of BC and sea salt are less biased, and sulfate and mineral dust slightly more, while the results for organics are inconclusive. Man-made aerosols now yield a stronger cooling effect on climate that is strong compared to results from IPCC.

We present a new version of the Compact Modeling Framework (CMF3.0) developed for the software environment of stand-alone and coupled global geophysical fluid models. The CMF3.0 is designed for use on high- and ultrahigh-resolution models on massively parallel supercomputers.

We discuss the question of whether weather forecast models that are based on deep learning and trained on atmospheric data can compete with conventional weather and climate models that are based on physical principles and the basic equations of motion. We discuss the question in the context of global weather forecasts. A toy model for global weather predictions will be presented and used to identify challenges and fundamental design choices for a forecast system based on neural networks.

This article compares global mesoscale ocean forecasts with different data assimilation cycle lengths. Mean absolute increment is used to quantify differences in the overall impact of observations. Greater observation impact does not necessarily improve a forecast system. Experiments show a 1-day cycle generates improved 7-day forecasts when compared to a 3-day cycle. Cycle length is an important choice that influences system bias and predictability.

The complexity of ice nucleation mechanisms and aerosol--ice interactions makes their representation still challenging in atmospheric models. We have implemented a comprehensive ice crystal formation parameterization in the global chemistry-climate model EMAC to improve the representation of ice crystal number concentrations. The newly implemented parameterization takes into account processes which were previously neglected by the standard version of the model.

In this paper, we introduce the most up-to-date version of the flexible tracer framework for the ICOsahedral Nonhydrostatic model with Aerosols and Reactive Trace gases (ICON-ART). We performed multiple simulations using different ICON physics configurations for weather and climate with ART. The flexible tracer framework within ICON-ART 2.1 suits the demands of a large variety of different applications ranging from numerical weather prediction to climate integrations.

In this project, we compare three different approaches to integrate the fluid-motion equations when applied to solve atmospheric flow dynamics. Differences between the three methods reside in accuracy as well as computational cost. The results illustrate that there is an intermediate solution that performs well in terms of computational cost while at the same time producing good enough results, as long one is not interested in the smallest turbulent scales.

Most existing global land surface models used to study impacts of climate change on water resources routinely use different models for near-surface unsaturated soil and the deeper groundwater table. We developed a model that uses a unified treatment of soil hydrologic processes throughout the entire soil column. Using a calibrated drainage parameter, the new model is able to correctly predict deep water table depth as reported in an observationally constrained global dataset.

The evolution of smoke depends acutely on where the smoke is injected into the atmosphere. This paper presents the development and implementation of a new global biomass burning emissions injection scheme for GEOS-Chem. The new scheme is based on monthly gridded Multi-angle Imaging SpectroRadiometer (MISR) global plume-height stereoscopic observations in 2008.

Single-column models have been used to develop weather and climate models for several decades. They decouple small-scale processes from large-scale forcing and allow us to test models in a controlled environment with reduced computational cost. Here, we present a fully coupled atmosphere–ocean single-column model, including sea ice. We demonstrate that it is a valuable tool to advance our understanding in marine and polar boundary layer processes and interactions of their coupled components.

Common global land cover and climate classifications are based on vegetation–climatic characteristics derived from observational data, ignoring the interaction between the local climate and biome. Here, we model the interplay between vegetation and local climate by discovering spatial relationships among different locations. The resulting global hydro-climatic biomes correspond to regions of coherent climate–vegetation interactions that agree well with traditional global land cover maps.

We conduct three simulations of atmospheric chemistry using chemical mechanisms of different levels of complexity and compare their results to observations. We explore situations in which the simplified mechanisms match the output of the most complex mechanism, as well as when they diverge. We investigate how concurrent utilization of chemical mechanisms of different complexities can further our atmospheric-chemistry understanding at various scales and give some strategies for future research.

Integrating vegetation in urban planning is promoted to counter steer potential impacts of climate and demographic changes. Assessing the multiple benefits of such strategies on the urban microclimate requires a detailed coupling of both the water and energy transfers in numerical tools. In this respect, the representation of water-related processes in the urban subsoil of the existing model TEB-Veg has been improved. The new model thus allows a better evaluation of urban adaptation strategies.

Weather and climate predictions of cloud, rain, and snow occurrence remain uncertain, in part because guidance from observation is incomplete. We present a tool that transforms predictions into observations from ground-based remote sensors. Liquid water and ice occurrence errors associated with the transformation are below 8 %, with ~ 3 % uncertainty. This (GO)²-SIM forward-simulator tool enables better evaluation of cloud, rain, and snow occurrence predictions using available observations.

Climate change is expected to have a significant impact on the Earth's weather, ice caps, land surface, and ocean. Computer models of the Earth system are the only tools available to make predictions about how the climate may change in the future. However, in order to trust the model predictions, we must first demonstrate that the models have a realistic description of the past. The BGC-val toolkit was built to rapidly and simply evaluate the behaviour of models of the Earth's oceans.

A novel configuration of an Earth system model includes a diverse plankton community. The model – EcoGEnIE – is sufficiently complex to reproduce a realistic, size-structured plankton community, while at the same time retaining the efficiency to run to a global steady state (~ 10k years). The increased capabilities of EcoGEnIE will allow future exploration of ecological communities on much longer timescales than have so far been examined in global ocean models and particularly for past climate.

The break-up of ice crystals in clouds is a possible secondary ice multiplication process to explain observations of very high concentrations of small ice crystals at cold temperature. Here, the process is modeled by considering shocks between fragile aggregates (assemblage of pristine crystals) and large densely rimed crystals of selected sizes. The simulations of two storms illustrate the perturbations caused by the break-up effect (precipitation, ice concentration enhancement).

During the Last Glacial Maximum, many rivers were blocked by the presence of large ice sheets and thus found new routes to the sea. This resulted in changes in the pattern of freshwater discharge into the oceans and thus would have significantly affected ocean circulation. Also, rivers found routes across the vast exposed continental shelves to the lower coastlines of that time. We propose a model for such changes in river routing suitable for use in wider models of the last glacial cycle.

We describe a new algorithm that automatically delineates the cliff top and toe of a cliffed coastline from a digital elevation model (DEM). The algorithm builds upon existing methods but is specifically designed to resolve very irregular planform coastlines with many bays and capes, such as parts of the coastline of Great Britain.

Due to incoherent methodologies, estimates of tropical width variations differ significantly across studies. Here, methods for eight commonly-used metrics of the tropical width are implemented in the Tropical-width Diagnostics (TropD) code package. The method compilation and analysis provide tools and information which help reduce the methodological component of the uncertainty associated with calculations of the tropical width.