A New High-Resolution Climate Record of Satellite-Based Estimates of Frozen Cloud Hydrometeors

Frozen cloud hydrometeors are an important component of the Earth's weather and climate system. In particular, extensive cirrus clouds produced by deep convective storms can significantly affect the Earth's energy budget by modulating top-of-the-atmosphere longwave radiative fluxes. Because of the important role of atmospheric ice in climate-relevant processes, the concentration of ice hydrometeors and its vertical integral, the ice water path (IWP), have been identified as crucial parameters for improving climate models and quantifying climate sensitivity. Despite this, the currently available observational record of cloud ice is severely limited. Combined radar and lidar estimates from the CloudSat and CALIPSO missions provide over a decade of high-quality estimates of ice hydrometeors, but they remain extremely sparse. While products derived from passive satellite sensors generally provide better spatio-temporal coverage, they tend to be in disagreement with the radar-lidar-based estimates.

This presentation introduces the Chalmers Cloud Ice Climatology (CCIC), a novel climate data record of IWP that overcomes these limitations. CCIC provides IWP estimates covering -60 S to 60 N at three-hourly resolution from 1983 and half-hourly resolution from 2000 to the present. The IWP estimates have been thoroughly validated against in-situ and radar measurements from various field campaigns. The long-term stability of CCIC is established by direct comparison to CloudSat/CALIPSO-based estimates over the full time range of data availability from these missions. Moreover, we compare CCIC to four other long-term IWP records and demonstrate that CCIC is the dataset that is most consistent with CloudSat/CALIPSO-based estimates, both in terms of global mean values as well as spatial and temporal climate variability.

The full CCIC record has recently been made publicly available. Its high spatiotemporal resolution and continuous coverage make it an ideal tool for the study of storm evolution and the validation of high-resolution climate models. The presentation showcases some of the early research on the validation of storm-resolving climate models. As such, CCIC will complement more accurate but sparse measurements from current and upcoming dedicated cloud missions such as EarthCare, INCUS, and PolSIR.