Into the Unknown

  • D-USYS
  • Institute for Atmospheric and Climate Science

An international team of scientists investigates air at altitudes up to 20 km starting from Nepal. Thomas Peter and three other members of the professorship of Atmospheric Chemistry at the Institute for Atmospheric and Climate Science (IAC) are among those present.

by Thomas Peter
Enlarged view: Maneuvering the aircraft out of Buddha Air Hangar at Kathmandu Airport (Photo: Thomas Peter).
Maneuvering the aircraft out of Buddha Air Hangar at Kathmandu Airport (Photo: Thomas Peter).

The Asian Monsoon System is one of the Earth’s largest and most energetic weather systems, and monsoon rainfall is critical to feeding over a billion people in Asia. The Monsoon also acts like an enormous elevator, pumping vast amounts of air and pollutants from the surface up to levels above 16km altitude. These altitudes are so high that monsoon air then ascends freely into the stratosphere, the stable layer that overlies the lower part of the atmosphere and contains the Earth’s protective ozone layer.

Once in the stratosphere, monsoon air spreads globally and persists for years. Satellite images show a large cloud of aerosols – small droplets or dust particles – directly above the monsoon and extending from the Arabian Peninsula to the eastern coast of China.

Enlarged view: The high-altitude research aircraft M55-Geophysica in Kathmandu (Photo: Thomas Peter).
The high-altitude research aircraft M55-Geophysica in Kathmandu (Photo: Thomas Peter).
Enlarged view: Balloon train: Measurements of water vapour, ozone, aerosols and clouds (Photo: Simone Brunamonti).
Balloon train: Measurements of water vapour, ozone, aerosols and clouds (Photo: Simone Brunamonti).

Tracking down the role of aerosols

The formation and properties of the aerosol cloud that sits above the monsoon are major unknowns in climate science, and their potential future changes represent one of the largest uncertainties in climate predictions. We also do not understand how monsoon rainfall will respond to changes in emissions of pollutants or to climate change.

An international team of scientists led by the Alfred Wegener Institute (AWI) in Bremerhaven is now setting out to close this gap of knowledge. The StratoClim project involves teams from 37 research institutions from 11 European countries, the United States, Bangladesh, India, and Nepal, and marks an important milestone in international research cooperation in the region.  

Enlarged view: Preliminary balloon measurements as function of altitude. Left: temperature and relative humidity. Right: backscatter ratio of aerosol and cloud particles (© ETH Zürich and DWD Lindenberg, Germany).
Preliminary balloon measurements as function of altitude. Left: Temperature and relative humidity. Right: Backscatter ratio of aerosol and cloud particles (© ETH Zürich and DWD Lindenberg, Germany).   

Clearance for take-off 

The StratoClim observations will provide the first close-up view of the upper reaches of the monsoon, as no prior research flights have ever sampled this critical part of the Earth’s atmosphere. Thomas Peter and Beiping Luo from Department of Environmental Systems Science (D-USYS) were involved in the intense flight planning activities for the aircraft. «Matching scientific interests with political sensitivities in the airspace between Nepal, India, China and Bangladesh requires particular care», says Thomas Peter. The Russian M55-Geophysica research aircraft took off from Kathmandu (Nepal) on 27 July to carry out its first scientific mission in the air spaces of Nepal, India and Bangladesh, carrying 25 specially developed scientific instruments to altitudes above 20 km – about twice as high as normal cruising aircraft can fly.

Mission planning with research balloons

Small research balloons help maneuver the aircraft into thin aerosol layers in the region, which are presumably of anthropogenic origin. ETH researchers Simone Brunamonti and Teresa Jorge are responsible to operate these balloons – jointly with colleagues from the German Weather Service.  «It is a main goal to steer the Geophysica into the right altitude.  We want to understand how this particle layer forms and how it – in turn – affects the monsoon», says Simone Brunamonti.  

To understand how the monsoon will respond to human emissions of pollutants and to climate change is obviously of crucial importance for the countries directly affected by it. But it matters to all of us as well. Because the monsoon drives weather patterns around the world and affects the stratosphere globally, this research will also improve our understanding of climate processes worldwide and enable better climate predictions from where we live.

The research project external pageStratoClim (Stratospheric and upper tropospheric processes for better climate predictions) is funded by the European Union. More than 30 research institutions and universities from 15 mostly European countries coordinated by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research are contributing to the project.

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