Simple Plumes

Simple Plumes (SP) is a representation to describe aerosol optical properties and aerosol effects on clouds globally. This mimics regionally characteristic seasonal cycles and trends in aerosol between the pre-industrial, present and projected futures at the end of the 21st century. It is computationally fast and flexible for using in multiple different models due to the use of mathematical functions that make regridding of data to model-specific spatial dimensions and wavelengths obsolete. Originally designed for anthropogenic aerosols (Stevens et al., 2017), it has been tested with different settings for the effects on clouds (Fiedler et al., 2017) and applied in CMIP6 historical and scenario experiments (Fiedler et al., 2019, 2023).

The SP is adapted to represent a variety of aerosol species, including anthropogenic particles, mineral dust, and sea salt. Expanding on earlier scaling, we are developing tools for a flexible integration of diverse data sources such as reanalysis datasets, data from satellite retrievals, and ground-based measurements of optical properties. The new developments provide a pragmatic and efficient way for representing aerosol changes in time and space in atmospheric models, without the need to run computationally expensive interactive aerosol modules for simulating their emission, transport and deposition. One application is the quick assessment of the sensitivity of radiative forcing to changes in emissions of aerosol and their precursors (between CMIP6 and CMIP7 data versions, Fiedler et al., 2025).

• Anthropogenic aerosols are represented using predefined plume patterns linked to major industrial and biomass burning regions.

• Temporal evolution is driven by scaling plume structures with SO2 and NH3 emissions, producing time-evolving global aerosol fields.

• The SPv2.1 dataset provides aerosol optical properties and cloud droplet number concentration from 1850 to 2023, and is being extended to future scenarios (until 2100) based on ScenarioMIP pathways spanning high to very low emissions for CMIP7 applications.

• Dust aerosol substantially influences regional climate change by absorbing and scattering radiation and influencing cloud processes.

• Interactive dust modules in CMIP6 models struggle to represent the historical increase of dust aerosol (Kok et al. 2023). Opportunity exists with Dust Plumes to exploit measurements from field campaigns and observational products to constrain dust properties in models.

• Dust Plumes provides an up-to-date estimate of the climatological distribution, optical properties and historical trend of dust aerosols, to deliver new estimates of forcing and climate response in participating models, e.g., in experiments requested for AerChemMIP2 ( Fiedler et al. 2026).  

   

• Oceans cover the majority of the planet, with sea salt influencing maritime climate. However, little work is done on assessing and improving simulated sea salt emissions in Earth system models.

• Sea salt emissions vary by up to 7 orders of magnitude across Earth system models (Grythe et al. 2014 ), and are for instance sensitive to the model’s accurate representation of the  near-surface winds.

• Sea Plumes uses global aerosol optical depth reanalysis products to simplify the sea salt emission representation while capturing the temporal and spatial variability and remaining adaptable to different input data sources.

   

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