Aerosol Feedbacks in High-Latitude Weather: Insights from Regional Modelling

Aerosol feedbacks significantly influence weather and climate predictions, particularly in high-latitude regions. Accurate representation of aerosols and their interactions with meteorological processes is critical for improving coupled atmospheric composition (AC) and numerical weather prediction (NWP) systems. In this study, we intercompare two state-of-the-art regional, online-coupled AC-NWP models, Enviro-HIRLAM and WRF-Chem, over high-resolution domains (both 15 km horizontal resolution) covering most of Russia, Eastern and Northern Europe, the Arctic and Atlantic Oceans, Greenland, Alaska, and Canada for July 2019. The focus is on assessing aerosol feedbacks and their impact on key meteorological parameters, including air temperature, cloud cover, total precipitation, and solar radiation.

Both models operate at the same horizontal resolution but differ in their physical and chemical representations. Enviro-HIRLAM utilizes the M7 aerosol module and EAC4 boundary conditions, while WRF-Chem employs the MOSAIC aerosol scheme with CAM-CHEM boundary conditions. Anthropogenic and ship emissions are consistent between models, based on the ECLIPSE and IPCC RCP inventories. Wildfire emissions are based on IS4FIRES for Enviro-HIRLAM, while WRF-Chem uses the FINN emission inventory. Additional differences arise in the treatment of natural aerosol emissions, including sea salt, dust, and DMS.

Preliminary results highlight key differences in aerosol-induced radiative and cloud feedbacks, with implications for surface temperature, radiation, and precipitation patterns. Model similarities and discrepancies are evaluated in the context of their chemical and aerosol parameterizations, meteorological drivers, and emissions datasets. The study provides insights into the strengths and limitations of the models and proposes strategies for improving aerosol feedback mechanisms in coupled AC-NWP systems for high-latitude regions.