Capabilities of the EUMETSAT Polar System Second-Generation Ice Cloud Imager

This study examines the ability of the future millimeter/submillimeter-wave (183-664 GHz) Ice Cloud Imager (ICI) to measure upper tropospheric ice clouds as compared to sensors on legacy satellite missions. This information will be used to identify which Environmental Data Records (EDRs) should be produced by NESDIS (including product requirements), determine what changes are needed to the STAR enterprise algorithms in order to create NOAA-unique EDRs, and, finally, to develop approaches for user engagement and exploitation of ICI data within the end user community.

The ICI will be launched in 2022 aboard the first of the EUMETSAT Polar System Second Generation satellites (METOP-SG A), with its primary objectives of supporting climate monitoring of ice cloud properties and validating and improving these properties in numerical weather prediction (NWP) models. It will yield direct, sensitive measurements of ice clouds and complement heritage observing systems by providing a fundamentally new source of data compared to past missions.

Initial product development efforts will largely be comprised of pre-mission radiative transfer modeling activities to understand the information content and ICI channel sensitivities to cloud ice content, ice water path, and effective ice particle size. Radiative transfer calculations will be undertaken using RTTOV (the Community Radiative Transfer Model does not currently cover the submillimeter wavelength range) for a unique sub-km global NWP simulation by the Non-hydrostatic Icosahedral Atmospheric Model. The horizontal model grid spacing of 870 m will allow for resolving smaller scale updrafts, leading to more realistic clouds for testing the capabilities of the ICI. The forward radiative transfer modeling will also use the latest ice single-scattering property database that considers particle habit and ice temperature.

Once synthetic ICI brightness temperatures have been created, these data will also provide information on how the ICI can complement the NOAA Enterprise Cloud Products generated from the METOP-SG A MetImage (a MODIS-like imager) and the NOAA Microwave Integrated Retrieval System (MIRS) products generated from the METOP-SG A Microwave Imager (MWI). The results of these studies will allow us to develop a strategy for the ICI and make an estimate of relevant requirements for the NESDIS ICI products.