Clouds and aerosols in the Southern Ocean

With Adrian McDonald (University of Canterbury) and Vidya Varma (NIWA).

In this seminar, Adrian and Vidya present their joint work on Clouds and Aerosols. Adrian discusses his team’s work collecting and analysing physical and satellite observations during recent voyages to the Southern Ocean. Vidya describes her work in our NZ earth system modelling programme to identify modelling errors (“biases”) and their underlying causes, and to begin to correct them. Clouds have a massive effect on our climate. Cloud cover reflects radiation from the sun that would otherwise be absorbed by oceans, raising their temperatures.

Cloud cover can also act as a blanket, keeping warmth near the surface. Despite their significant influence on climate, clouds still represent the largest source of uncertainty in modern climate models. For example, the frequency of clouds over the Southern Ocean is often underestimated, causing models to predict warmer sea surface temperatures than observed.

In turn, this leads models to predict the strength and position of the storm tracks incorrectly. Storm tracks impact New Zealand directly – bringing not only extreme weather events but also contributing to longer-term changes such as drought or changing rainfall patterns. It is vital to correct the way clouds are represented in our models, so we can increase certainty in our climate projections for New Zealand.