Satellite-based estimation of contrail cirrus cloud radiative forcing derived through a Rapid Contrail-RF Estimation Approach

Abstract. Geostationary satellite observations were used to estimate the radiative forcing of contrail cirrus clouds through a Rapid Contrail-RF Estimation Approach. Meteosat Second Generation/ Spinning Enhanced Visible and InfraRed Imager (MSG/SEVIRI) observations were utilized to visually identify days with contrails. For six selected days, ice clouds were characterized using the Optimal Cloud Analysis (OCA) product from MSG/SEVIRI data provided by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). Look-Up Tables (LUTs) were constructed using the libRadtran radiative transfer (RT) model to quantify the radiative effect of ice clouds in the shortwave (SW) and longwave (LW) spectral regions. The retrieved cloud properties were combined with the LUTs to generate radiative forcing maps for natural and contrail cirrus clouds. A separation scheme isolated the radiative forcing of contrails. The resulted dataset provides a quantification of the SW, LW and net radiative forcing at the top of the atmosphere (TOA) due to contrails. Over the full diurnal cycle, contrails cause a cooling effect during the daytime and warming at night. The Rapid Contrail-RF Estimation Approach's validity was assessed through correlative exercises focusing on uncertainties in the use of LUTs, a single ice cloud parameterization, and a calculated cloud top height (CTH), supplemented by comparisons with polar-orbiting satellite observations from the Clouds and the Earth's Radiant Energy System (CERES) instruments. Overall, these correlative comparisons indicate that the proposed approach provides accurate data on contrails radiative forcing estimation, with an accuracy on the order of approximately 15 %.