High flyers get ACTIVE down under

20 April 2006

A project high in the sky above Darwin Australia is the first to have examined important aspects of the huge tropical thunderstorms that form in the region.

British scientists, led by the University of Manchester, found that air flowing into the storms can vary enormously in the amount of pollution it contains.

The researchers are evaluating what effect this has on the storms and the properties of the clouds and air flowing from them at high altitudes.

This affects how the atmosphere interacts with incoming sunlight, which in turn affects the climate.

Storm cell seen from NERC Dornier

As part of the Natural Environment Research Council's "Aerosol & Chemical Transport in Tropical Convection" (ACTIVE) project, the British research team, which includes teams from Cambridge and York Universities, used the NERC Airborne Research and Survey Facility's Dornier aircraft to fly 30 missions around tropical storm clouds, especially the "Hector" storm cell which formed over the Tiwi islands north of Darwin.

The Dornier was equipped with a range of high-tech probes to measure the aerosol particles and gases that were being drawn into the tropical storms.

Aerosols include materials like desert dust, sea salt and other organic "biomass" materials - which are drawn up into the clouds from the earth's surface. These particles influence the physics of the clouds and can have a dramatic effect on the climate process.

A total of seven aircraft and teams from the US Atmospheric Radiation Measurement (ARM) programme, the Australian Bureau of Meteorology (BoM), and the European SCOUT consortium flew missions from Darwin as part of the international study.

Professor Geraint Vaughan of Manchester University who led the ACTIVE programme said:

"ACTIVE was the first experiment to investigate the particle transport process in the Micronesian region, which is critical to the global climate system.

Large variations in air composition at low levels were found during the different phases of the campaign; these will allow us to determine how sensitive the upper tropospheric composition is to convective transport processes."

The ACTIVE team used a second aircraft, the Airborne Research Australia (ARA) Egrett, to measure the clouds, aerosols and gases at high altitudes - up to 36,000 feet.

Spikes of high nitrogen oxide levels were observed in the outflow from the storm clouds. These are produced by lightning within the storms and from biomass burning on the ground.

These gases can affect the chemistry occurring high up in the atmosphere, influencing the concentration of greenhouse gases.

"Large tropical thunderstorms are a means of transporting aerosols and chemicals very quickly from the earth's surface to high levels in the atmosphere, where they can influence cloud processes and the distribution of greenhouse gases." says Professor Vaughan.

Further information

NERC Press Office
Natural Environment Research Council
Polaris House, North Star Avenue
Swindon, SN2 1EU
Tel: 01793 411561
Mob: 07917 557215

Simon Hunter
Media Relations Officer
University of Manchester
Tel: 0161 2758387

Notes

1. ACTIVE is a NERC-funded consortium project involving the universities of Manchester, Cambridge and York (UK); DLR and Forschungszentrum Jülich (Germany); York University (Canada), Bureau of Meteorology (Australia) and Airborne Research Australia. The ACTIVE project builds on research carried out in 2002 as part of the EMERALD-2 campaign, which sought to measure cirrus outflow from topical convection.

2. Geraint Vaughan is a Professor of Atmospheric Science within the University of Manchester's School of Earth, Atmospheric & Environmental Sciences, which is part of the Faculty of Engineering & Physical Sciences.

3. The Dornier aircraft is operated by NERC's Airborne Research & Survey Facility (ARSF) in Oxfordshire.

4. NERC is one of the UK's research councils. It uses a budget of about £350m a year to fund and carry out impartial scientific research in the sciences of the environment. NERC trains the next generation of independent environmental scientists. It is addressing some of the key questions facing mankind, such as global warming, renewable energy and sustainable economic development.

High flyers get ACTIVE down under

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