TWSTSAIL

Field Validation of Cloud Properties Sensor - SAIL

18 October 2021 - 15 June 2023

Lead Scientist: Stephen Jones

Observatory: AMF

Part of the ARM mission is generally to gain a better understanding of the water cycle. Clouds are a very significant component of Earth's radiation budget. Better measurements of cloud properties such as cloud optical depth, droplet effective radius, and thermodynamic phase could improve this understanding. A low-cost sensor could enable a greater number of sensor deployments. Aerodyne has developed TWST-CPS (Cloud Properties Sensor), a low-cost, zenith viewing, VIS-NIR (400-1700 nm) spectroradiometer-based instrument with ½-degree field of view and 1 Hz measurement rate. As part of a DoE SBIR (Phase 1 and 2), we deployed this sensor at ARM’s Southern Great Plains (SGP) observatory during spring/summer 2020 and June-December 2021. We demonstrated excellent agreement of cloud optical depth (COD) and liquid water path (LWP) with other sensors of different modalities. Effective radius and thermodynamic phase retrievals have been good but are still under development for improvement. Deployment of TWST-CPS for the SAIL campaign will be an ideal opportunity to further validate the new instrument in an environment different than SGP. For example, the typical snow cover at SAIL will provide a much different surface albedo than SGP. As at SGP, the SAIL deployment will allow correlative measurement comparisons with instruments of various modalities and their value-added products, e.g., MWR/MWR3C (passive microwave), AERI (LWIR), KAZR (mm-wave radar), CSPHOT, and MFRSR (VIS/NIR).