The CAST dataset contains data produced by the the NERC Co-ordinated Airborne Studies in the Tropics (CAST) project. CAST was a collaborative initiative with NASA's Airborne Tropical Tropopause Experiment (ATTREX) programme to study the Tropical Tropopause Layer (TTL) over the Pacific Ocean and South East Asia.

This data collection includes airborne measurements made by the FAAM (Facility for Airborne Atmospheric Measurements) BAe-146 aircraft whilst deployed in Guam in Jan/Feb 2014 during coordinated flights with NASA's Global Hawk making corresponding in situ measurements in the TTL over the West Pacific. In addition to these in situ aircraft measurements, the dataset comprises balloon-based measurements of ozone and ground-based ozone, CO2, CH4, CO and very short-lived halogen species. A complementary group of regional high resolution models, global composition models and a global cirrus model will also be used to address fundamental questions related to atmospheric composition, radiation and transport.