Circcrex: A New Cirrus Dataset for Model Evaluation

The Cirrus Coupled Cloud-Radiation Experiment (CIRCCREX), a new NERC-funded airborne research campaign, aims to understand the link between evolving ice cloud microphysical properties and cirrus radiative signatures at the macrophysical scale. CIRCCREX will obtain for the first time radiation measurements across the electromagnetic spectrum (visible to sub-mm wavelengths) together with state-of-the-art cloud microphysical measurements. These datasets will be utilised to achieve the overall goal of an accurate parameterisation of cirrus optical properties in global climate modelling and Numerical Weather Prediction, through testing and facilitating improvement of cirrus scattering models and investigation of the sensitivity of the radiance to Particle Size Distribution, habit types and crystal complexity. Presented here is an overview of CIRCCREX, the relevant background and previous results. Findings from the first stage of the research campaign, which took place over Prestwick, UK in November 2013, are reported with an emphasis on performance of cirrus radiative and scattering models. High resolution far- and mid-infrared spectra recorded over cirrus scenes are presented and linked to micro- and macro-physical cirrus properties. Uncertainties and challenges in both observations and model simulations are discussed, along with improvements for the next stages of the campaign.