We present our first laboratory calibration and field results of a newly developed commercial ice nucleation chamber, the so-called PINE. The PINE instrument is developed based on the design of the AIDA cloud chamber (Möhler et al., 2003) to advance online atmospheric ice nucleation research. A unique aspect of the PINE chamber includes its plug-and-play feature (so it runs on a standard power outlet), autonomous cryo-cooler-based temperature-ramping operation, capability of quantifying INPs in different IN modes (e.g., immersion freezing and deposition mode at >-60 °C), small particle loss through the system (~5% for <5 m diameter particles), and sensitive optical particle detection of INP concentration (≤0.1 L-1 at T > -15 °C), promising stand-alone operation at remote locations. To date, the PINE chamber has been calibrated using test aerosol particles with known properties (e.g., illite NX). Briefly, test particles were exposed to ice supersaturation conditions, where a mixture of droplets and ice crystals were formed during the ‘expansion’ experiment. A comparison of our calibration test results to other techniques will be presented. Further, the PINE instrument has been tested in field campaigns in the Southern Great Plains. With a turnover time of ~6 minutes, PINE ran continuously and scanned at different temperature intervals to assess different INP episodes. We made sure to assess at least a few degrees of common temperature interval in a series of scan. Our first field results will be shown. Our results suggest that using this autonomous instrument may be critical to minimize error sources in high-temperature and supermicron INP research. Acknowledgement: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research (DE-SC0018979) – work packages 1-2 of Implications of Aerosol Physicochemical Properties Including Ice Nucleation at ARM Mega Sites for Improved Understanding of Microphysical Atmospheric Cloud Processes. References: • DeMott, P. J. et al. Resurgence in ice nuclei measurement research. Bull. Amer. Meteorol. Soc. 92, 1623, doi:10.1175/bams-d-10-3119.1 (2011). • Möhler, O. et al. Experimental investigation of homogeneous freezing of sulphuric acid particles in the aerosol chamber AIDA. Atmos. Chem. Phys. 3, 211-223 (2003).

This study was conducted to assess precipitation particle properties, including ice-nucleating particle (INP) concentration (L^-1 Air), in West Texas, where the semi-arid climate prevails and typically <40 inches of rainfall coincides per year. Further, the West Texas region is dominated by deep convective clouds, where INPs play a crucial role in hailstorm and thunderstorm processes (e.g., Li et al., 2017; Rosenfeld et al., 2008). In this study, we looked into major precipitation events observed throughout the year in 2018 and 2019 in the Texas Panhandle area. More specifically, to characterize immersion freezing efficiency (T > -25 degree C) of our precipitation samples, we used a cold-stage instrument called West Texas Cryogenic Refrigerator Applied to freezing Test (WT-CRAFT) system (Hiranuma et al., 2019). Additionally, a disdrometer is used to look into the relationship between INP concentration, intensity and size of precipitation particles. An indigenously developed Internet of Things (IoT) air quality sensors were also used to compare ambient air quality (i.e., particulate matter concentrations) and meteorological conditions to the measured INP concentrations. Overall, the study’s preliminary results show a reasonable correlation between INP concentration and precipitation properties (i.e., intensity). We also find a high ice nucleation efficiency at higher temperatures (i.e., T > -15 degree C), which can be attributed to the biological INPs from local agricultural sources. The results also suggest that INPs play an important role in the precipitation particle size. These findings may be important in artificially varying the severity of the precipitation by varying the INP concentration in the West Texas region.