Development of an Ice Nuclei Observation Framework and Database as Part of the BACCHUS Project

The response of aerosol and cloud processes to changes in anthropogenic and natural emissions and climate is the most uncertain climate feedback. This uncertainty may be due to a poor understanding about ice-containing clouds and the incomplete knowledge of the coupling between the biosphere and atmosphere. Ice nuclei (IN) measurement capabilities are still insufficient and our understanding of ice formation and ice cloud evolution in different environments is poor.

IN measurements are starting to become more widespread with the development of new instruments that begin to meet the needs for studies of aerosol effects on ice-containing clouds. As part of the European FP7 project BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding), long-term IN measurements will commence within the Amazon, the Swiss Alps, Germany, Cyprus, Martinique and Spitzbergen. Short-term ground, air and remote observations, which will include vertical profiles, will be made at targeted locations. Based upon these observations, as well as further observations in northern Europe as part of the CRAICC (CRyosphere-Atmosphere Interactions in a Changing Arctic Climate) program and historical observations, a comprehensive database of IN observations will be produced. Additional to the development of this database, a measurement framework will be defined specifying parameters such as the relative humidity and temperature for the analysis of the IN-activated fraction. This framework will establish a harmonization scheme for future projects including IN measurements using comparable instrumentation.

The creation of a quality controlled and harmonized database will enable the improvement of the accuracy of atmospheric models that include heterogeneous ice nucleation processes. Further, this database will include a vertical dimension enabling integration and closure studies with other data sets including those from satellites. It may also provide the basis for identifying the effects of anthropogenic and natural emissions on mixed-phase cloud properties, and will be used to develop and test/validate new parameterisations against data. Preliminary designs for the framework and database will be presented.