COntrails Spreading Into Cirrus (COSIC) aims to quantify the climate role of line shaped contrails caused by air-traffic that you often see in the sky. In particular, we aim to understand how they can sometimes spread into larger cloud decks. Such spreading contrails could add significantly to the CO2-driven climate impacts of aviation, but estimates of their effect are very uncertain.

COSIC has made direct measurements of spreading contrail using dedicated flights over the UK with the BAe-146-301 large Atmospheric Research Aircraft. These measurements are now being used to incorporate spreading contrails into models of climate change. COSIC also aims to understand various stakeholder needs for aviation-climate science and communicate science results in the most appropriate way to the industry, policy makers and the public.

COSIC is a Natural Environment Research Council (NERC) sponsored project led by the University of Leeds, collaborating with the Universities of Manchester and Reading, the UK Met Office, the Facility For Airborne Atmospheric Measurements (FAAM) and the Institut für Physik der Atmosphäre, DLR, Germany.