British scientists go cloud-hopping in the Pacific to improve climate predictions

A 20-strong -team of cloud and climate experts from the UK's National Centre for Atmospheric Science will today set off for Chile to investigate how massive swathes of clouds that hang over the Pacific are affecting climate and weather all round the world, including the UK. This new £3M project aims to reduce some of the largest errors currently in our climate models and thus greatly improve predictions of future climate change.

These immense clouds – often exceeding the area of the USA in size – are believed to be central to global climate because they act like a colossal mirror, reflecting sunlight back into space and substantially reducing the amount of energy reaching the Earth's surface. They also help keep the ocean cool beneath them. Both of these effects greatly impact the amount of heat transported to the tropical Pacific affecting its climate and having a knock-on effect for weather around the world.

During this month-long expedition scientists will determine how and why these clouds form so that they can be more accurately represented in global climate models. Joining forces with the UK Met Office, the team will fly in two UK research aircraft, swooping in and out of these vast, low-lying clouds, collecting detailed measurements that describe the clouds' properties.

Using newly developed cloud and dust probes fitted to the aircraft, the scientists will determine exactly how the clouds form, how reflective they are and what determines their lifetime. Importantly, they aim to establish whether man-made pollution, from extensive mining activities along the Chilean and Peruvian coasts plays a significant role in changing cloud properties. Tiny particles emitted during mining vastly increase the number of water droplets that form in the clouds and may affect how much rain they produce. The scientists will also find out whether clouds made from these particles are more reflective than cleaner clouds so having a greater affect on climate.

Lead scientist, Professor Hugh Coe from the National Centre for Atmospheric Science said: “These are some of the largest cloud systems in the world and we know they must play a very significant role in climate change, yet we know that climate models do not represent them very well. This campaign is a fantastic opportunity to make cutting-edge measurements in a unique environment and merge them with state-of-the-art climate models. By working closely with the Met Office and international colleagues in this way, we hope to finally hit some of the uncertainties in current climate models on the head”

This UK project forms part of a much larger international programme of work called VOCALS (VAMOS Ocean Cloud Atmosphere Land Study), which considers in detail the complex feedbacks between clouds, ocean, land (the Andes) and how these affect the global climate. The UK team will be joining forces with over 200 other international scientists from 10 different countries to carry out the field campaign, and a total of 5 research aircraft and two research vessels will be involved.