Cloud & aerosol observations to improve the NZESM

Clouds have a surprisingly large effect on our climate. In particular, cloud cover reflects sunlight back into space that would otherwise be absorbed by oceans, potentially raising their temperatures. Despite their significant influence on climate, clouds still represent the largest source of uncertainty in modern climate models.

The frequency of clouds over the Southern Ocean is often underestimated, causing models to predict warmer sea surface temperatures than observed. Models also often misrepresent the composition of clouds because of the importance of small particles, called aerosols, which act as the starting points for cloud droplets and ice to form around.

These deficiencies in turn leads models to predict the strength and position of the Southern Hemisphere storm tracks incorrectly. These storm tracks impact New Zealand directly via their influence on rainfall and also bring extreme weather events. It is vital that our models represent clouds well so we can increase certainty in our climate projections for New Zealand.

Our project aims to use detailed measurements to compare with simulations of the present-day to critically test the quality of cloud and aerosol simulations. By analysing these differences and using our understanding of how cloud processes work we can develop improved model simulations.