Addressing the Arctic cloud problem in regional and global models


Gillian Young
Photo: Private

Speaker: Gillian Young Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, UK

Clouds are a key component of the Arctic climate system. They warm or cool the surface by trapping terrestrial heat or reflecting solar radiation and are the primary control for the surface energy balance. However, numerical models often fail to capture their long lifetime and associated radiative impact due to the poor representation of small-scale interactions which occur internally within the clouds themselves and externally with their environment. Such processes act on scales much smaller than the grid size of a climate model, and the mathematical relationships we use to describe them in our model world are typically still based on knowledge gained from the mid-latitudes. These relationships are therefore often inappropriate for the unique polar atmosphere, and are likely hindering our ability to properly model the role of clouds in the Arctic climate system.

Using measurements from the recent Arctic Ocean 2018 expedition to the central Arctic, I will show that two different large-scale models – the Met Office Unified Model and European Centre for Medium-range Weather Forecasting Integrated Forecasting System – have consistent weaknesses when simulating Arctic clouds and their interactions with their environment. By identifying where these models are under-performing, we can inform development strategies to improve our Arctic cloud modelling capability and thus enable more representative predictions of the future Arctic climate.

Icebreaker Oden
Photo: Ian Brooks, University of Leeds