TY - JOUR AU - Lloyd, Gary AU - Gallagher, Martin AU - Choularton, Thomas AU - Krämer, Martina AU - Petzold, Andreas AU - Baumgardner, Darrel TI - In Situ Measurements of Cirrus Clouds on a Global Scale JO - Atmosphere VL - 12 IS - 1 SN - 2073-4433 CY - Basel, Switzerland PB - MDPI AG M1 - FZJ-2021-04222 SP - 41 - PY - 2021 AB - Observations of high-altitude cirrus clouds are reported from measurements made during the routine monitoring of cloud properties on commercial aircraft as part of the In-Service Aircraft for a Global Observing System. The increasing global scale of the measurements is revealed, with 7 years of in situ data producing a unique and rapidly growing dataset. We find that cloud fractions measured ≥ 10 km at aircraft cruise altitude are representative of seasonal trends associated with the mid-latitude jet stream in the Northern Hemisphere, and the relatively higher cloud fractions are found in tropical regions such as the Inter-Tropical Convergence Zone and South East Asia. Both stratospheric and tropospheric data were used to calculate the cloud fractions routinely experienced by commercial aircraft. Further work is needed for a direct comparison with previous studies that limit cloud fraction calculations to tropospheric data only. The characteristics of these clouds are discussed and the potential different formation mechanisms in different regions assessed LB - PUB:(DE-HGF)16 UR - <Go to ISI:>//WOS:000609739700001 DO - DOI:10.3390/atmos12010041 UR - https://juser.fz-juelich.de/record/902388 ER -