Exploiting Synergies between Remote Sensing and in Situ Measurements during ICE-T to Better Understand Ice Generation in Tropical Clouds

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Despite longstanding recognition of the importance of ice nucleation and multiplication processes in clouds, both for precipitation processes as well as for the radiative impact of clouds on global climate, our understanding of heterogeneous ice nucleation mechanisms and the relevance of ice multiplication processes remains limited. The gaps in our understanding of ice formation processes hinder parameterization of ice initiation processes in numerical simulations of clouds, thus leading to uncertainties in cloud radiative properties and precipitation simulated in numerical models.The Ice in Clouds Experiments (ICE) are a series of field campaigns investigating ice nucleation in clouds in a range of different conditions, taking advantage of improvements in observational capabilities including improved in situ probes and airborne Doppler radar and lidar. ICE-Tropical (ICE-T), will investigate ice formation in shallow, convective clouds over the eastern Caribbean.Intellectual merits. The Wyoming Cloud Radar (WCR), together with upward- anddownward-looking versions of the Wyoming Cloud Lidar (WCL) will be flown on the NSF (National Science Foundation)/NCAR (National Center for Atmospheric Research)C-130 aircraft during ICE-T and will be used to observe ice occurrence within cloud.This research will help understanding the relationship between cloud-dynamics andmicrophysical processes. Lidar backscatter and depolarization measurements will be used in conjunction with the PCASP (Passive Cavity Aerosol Spectrometer Probe) and FSSP-300 (Forward Scattering Spectrometer Probe) measurements to identify aerosol distributions and dust layers. The effect of dust on ice formation in clouds will be examined by contrasting ice formation and development in clouds under dusty vs. non-dusty conditions.The dual-Doppler capability of the WCR will be used to investigate how ice is transported inside cloud, and explore the link between cloud dynamics and iceinitiation/multiplication. The combination of WCR and WCL will allow the reflectivity and velocity fields observed by the radar to be unambiguously linked to the boundaries ofthe mixed-phase region.Broader impacts. Radar, lidar, and in situ aerosol data collected during thisinvestigation will facilitate analyses conducted by other ICE-T investigators. A graduatestudent will participate in the ICE-T field campaign and data analysis phase. Data dissemination and other broader outreach efforts will also be carried out through various phases of this project. Finally, an improved understanding of ice nucleation andmultiplication mechanisms in the atmosphere will lead to improved parameterizations ofice processes in numerical models, in turn lead to a better cloud simulations in globalclimate models.