A Cirrus Cloud Analysis Comparing Modeled CRF from Constrained Lidar Extinction Retrievals and Coincident Radiometer Measurements

Cirrus are the most common cloud type in the atmosphere (Stubenrauch et al. 2013), and play a crucial role in modulating Earth’s radiative energy balance. Due to their complexity, cirrus are poorly represented in global circulation models (GCM), and are a significant source of uncertainty. They are the only cloud type that can have a positive net daytime radiative forcing (RF) at the top of the atmosphere (TOA), however, depending on their microphysical properties can also have a net cooling affect (Campbell et al. 2016). Lidar instruments provide valuable vertical profiles of cirrus layer optical properties, which are incorporated into radiative transfer (RT) simulations. The NASA Cloud Physics Lidar (CPL) flew in the Radiative Effects of Thin Cirrus (REThinC) campaign out of Houston, TX in August 2018. RT simulations incorporating CPL constrained extinction retrievals from REThinC were ran using the Fu-Liou Gu (FLG) (Fu and Liou, 1992; Gu et al., 2003) RT model to estimate TOA RF values. Here, the TOA RF estimates of CPL profiles are examined from multiple FLG model runs incorporating varying microphysical parameterizations. Coincident radiometer measurements taken during the REThinC science flights are also used to further compare and contrast cirrus profile RF values from the modeled estimates. These comparisons provide valuable insight into the deviation of modeled RF estimates from direct radiometer measurements along with the impact and importance of correctly parameterizing microphysical properties.