Large-eddy modelling: UCLALES-SALSA

Large-eddy simulation (LES) models are numerical tools designed to describe turbulent flows in the atmosphere. UCLALES-SALSA is one such model, whose main application is simulating cloud properties and evolution. In UCLALES-SALSA, the LES core is coupled with a spectral description of aerosol particles, cloud droplets and other hydrometeors, complete with the essential microphysical processes, such as vapor condensation/evaporation, droplet formation, collision and coalescence between particles, and rain formation. To capture the structure of the turbulent flow, the model is run at a very high spatial resolution (usually less than 100 m). Thus, the total computational area is also small compared to e.g. regional models, typically on the order of about 10 km across. The main intention of the model is to provide a detailed view on the microphysical processes acting within the turbulent boundary layer, and how the small-scale dynamics interact with the aerosol and cloud properties. This information can then be used to improve parameterized descriptions of these effects in larger-scale models, or to help interpret ground-based as well as space-borne measurements. Model description: Tonttila, J. et al.: UCLALES–SALSA v1.0: a large-eddy model with interactive sectional microphysics for aerosol, clouds and precipitation, Geosci. Model Dev., 10, 169–188, https://doi.org/10.5194/gmd-10-169-2017, 2017.

Regional climate modelling: HCLIM

Regional climate modeling (RCM) is used to understand and predict climate patterns over a specific area or region, as opposed to global climate models which cover the entire Earth. Since RCMs only cover a limited domain, they can be used with much higher grid resolution (even 1 km x 1 km) than global climate models with the same computational resources. This allows simulating forcings and processes which are usually not possible with global climate models, such as complex topography, coastlines, lakes, land cover distribution and smaller scale dynamical processes. By providing a closer look on climate at a regional level, regional climate modeling helps various stakeholders make informed decisions based on the climate realities of their specific area. The driving data (boundary conditions) for RCMs are derived from global climate models or observational based reanalysis. In our group, we use the Harmonie Climate (HCLIM) model. HCLIM is a regional climate modelling system based on the ALADIN-HIRLAM numerical weather prediction system. Model description: Belušić, D. et al.: HCLIM38: a flexible regional climate model applicable for different climate zones from coarse to convection-permitting scales, Geosci. Model Dev., 13, 1311–1333, https://doi.org/10.5194/gmd-13-1311-2020, 2020.

Earth system modelling: EC-Earth

Earth System Models (ESMs) are comprehensive computational frameworks used to simulate and understand the interactions within the Earth's system. They encompass various components including the atmosphere, oceans, sea ice, land surface and biogeochemistry. By integrating these elements, ESMs aim to provide a holistic view of how the Earth system operates and how it might change over time under different circumstances. ESMs are crucial tools that help in both advancing scientific understanding and in the practical application of climate science for societal benefit. EC-Earth is a climate modeling framework developed as a collaborative effort among several European national meteorological services and research institutes, including FMI. EC-Earth consists of the atmospheric model IFS, ocean model NEMO, aerosol-chemistry model TM5, land model LPJ-GUESS and ocean biochemistry model PISCES. The EC-Earth consortium has contributed to the Coupled Model Intercomparison Project (CMIP). IPCC reports rely on CMIP projections to assess potential future climate change and its impacts. Our group’s work in the EC-Earth consortium is concentrating on aerosol and helping to improve how we simulate and understand aerosol-cloud interactions in the climate system. For example, we have played a significant part in incorporating the HAM aerosol model into the upcoming version of the EC-Earth climate model. In addition to EC-Earth, our group is also using other ESMs such as MPI-ESM and CESM. Model description: van Noije, T. et al.: EC-Earth3-AerChem: a global climate model with interactive aerosols and atmospheric chemistry participating in CMIP6, Geosci. Model Dev., 14, 5637–5668, https://doi.org/10.5194/gmd-14-5637-2021, 2021.