ALBERT

Description: Ice clouds are a major source of uncertainty within climate projections. The upcoming Ice Cloud Imager (ICI) mission is designed to address the lack of cloud ice observations contributing to this issue. ICI will measure within a frequency range of 183 GHz to 664 GHz, bridging current gaps in observations. The sub-millimetre wavelengths are particularly suited for interaction with ice hydrometeors. Therefore, ICI will provide reliable global data on cloud ice on a daily basis. Since ICI is the first-of-its-kind, retrieval schemes require rigorous 'all-sky' simulations. However, modelling the cloud-radiation interaction is challenging due to the complex microphysics of ice clouds and the novelty of the wavelengths. The generation of a cloud radiation database will be covered, focusing on radiative transfer calculations. The database contains pairs of simulated observations and atmospheric states, offering global and seasonal coverage. Ice hydrometeors are represented by particle models that combine single scattering data with empirically-based assumptions on size and shape. An approximation to particle orientation is implemented, allowing for polarisation effects to be captured. Atmospheric states capture the three-dimensional variability of cloud structure. The database shows statistical consistency with global radar retrievals (DARDAR). Observations are simulated for airborne (ISMAR) and satellite (GMI) missions and compared to existing observations. Inversions of real observations are performed, and results show realistic spatial distributions. The database is state-of-the-art, containing the most realistic simulations of ICI radiances to date. Post-launch, retrievals will be performed on real ICI measurements, providing valuable data for use within climate monitoring, modelling, and numerical weather prediction.