New Progress in Leveraging Spaceborne Radar and Lidar to Advance Arctic Cloud-Climate Research

The active sensors CloudSat (radar) and CALIPSO (lidar) provide nearly a decade of pan-Arctic cloud and precipitation measurements. Taken together, these two satellites observe cloud properties with relevance to both climate feedbacks and hydrological cycle changes in a warming world. Most importantly, these two satellites constrain hydrometeor properties with vertically resolved surface-blind retrievals that directly detect hydrometeor vertical structure. Here, we report on two recent research results that leverage the full decade of CloudSat+CALIPSO observations available. First, we isolate the cloud response to sea ice loss for the first time. The observations show no summer cloud response to Arctic sea ice loss, but increased cloud cover and a deepening atmospheric boundary layer in fall. We attribute the fall cloud response to observed sea ice loss caused in part by human greenhouse gas emissions. Second, we confront a community climate model (the latest version of the Community Earth System Model) using process-oriented diagnostics from CloudSat+CALIPSO observations. We work within a satellite simulator framework to ensure robust scale-aware and definition-aware comparisons. We present new diagnostics for opaque clouds and precipitation occurrence based on CloudSat+CALIPSO. The new diagnostics are simple and directly constrain cloud-climate radiative feedbacks and hydrologic cycle changes. It’s all a tall order, but our results illustrate the power of active sensors to advance Arctic cloud-climate research.