High resolution sensitivity study of information content in the reflective solar band for retrieval of ice cloud optical properties

Abstract:

Ice cloud microphysical and optical properties (i.e., the effective particle radius and optical depth) are among the most uncertain components in our understanding of cloud-climate forcings and feedbacks. Reduction in cloud feedback uncertainty is recommended as a most important endeavor by the National Academy of Sciences 2017 decadal survey. Hyperspectral measurements of clouds are important due to the potential for rich information content in a multitude of channels. Several hyperspectral instruments are in development whose dense spectral content will allow for the identification of optimal channel configurations for retrieval of cloud properties under various conditions, including the Climate Absolute Radiance and Refractivity Observatory-Pathfinder (CLARREO-PF). Hyperspectral instruments, with tight/overlapping spectral channels, contain denser information content as compared to multispectral instruments. Our ultimate goal is to develop a robust method to infer ice cloud optical depth, effective radius, and height of cloud tops for hyperspectral measurements of reflected radiances. Using CLARREO-PF as a guide, we will investigate sensitivities in the 350-nm to 2300-nm region to optical depth, effective radius, and cloud height as well as quantify uncertainties in this sepctral regime to assumptions in ice crystal optical property model (in particular, the effect of crystal habit), atmospheric state parameters, and instrumentation. Moreover, a preliminary analysis of the information content of 640 possible CLARREO-PF channels will be presented.