INCA funded by the European Community 
through the Fifth Framework Programme

Interhemispheric differences in cirrus properties from anthropogenic emissions (INCA)


Coordinated by Johan Ström, Stockholm, Sweden

Geographical Distribution of Previous Insitu Measurements of Cirrus Properties

Source: A. Heymsfield (1999)


2.1.1    Atmospheric composition change
2.1.2    Stratospheric ozone depletion
2.1.3    Climate change prediction and scenarios

Brief Description of the Research Project:

Very small particles in the atmosphere, called aerosols, do influence the earth's climate, directly by absorbing and scattering solar and terrestrial radiation, and indirectly by modifying the formation processes and radiative properties of clouds. Therefore additional anthropogenic emissions of gases and aerosols either from sources at the ground or from air traffic alter the earth's radiative budget and the amount and properties of clouds.
Especially the relation between aerosols and cirrus clouds needs further investigations. Cirrus clouds appear at altitudes of about 7 to 11 km and consist mainly of ice particles. The radiative properties of cirrus clouds and the specific surface area of particles and ice crystals is of  importance  for climatic and air cemistry processes. These processes depend on numerous parameters as ambient conditions during cloud formation, structure and amount of clouds, thickness and water content of clouds, or the concentration, composition, and shape of the ice crystals, respectively.

The main goals of the project therefore are

The measurements using the same instrumentation and the same observation strategy are scheduled for March / April 2000 in Punta Arenas, Chile, and for September / October 2000 in Shannon, Ireland. Both campaigns will be performed at comparable geographical latitude (50°S and 50°N, respectively) and at the same season in local autumn.