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Abstract: Ice nucleating particles (INP) have been found to influence the amount, phase, and efficiency of precipitation from winter storms, including atmospheric rivers. Warm INP, those that initiate freezing at temperatures warmer than -10 C, are thought to be particularly impactful because the can create primary ice in mixed-phase clouds, enhancing precipitation efficiiency. The dominant sources of warm INP during atmospheric rivers, the role of meteorology in modulating transport and injection of warm INP into atmospheric river clouds, and the impact of warm INP on mixed-phase cloud properties are not well-understood. Time-resolved precipitation samples were collected during an atmospheric river in Northern California, USA during winter 2016. Precipitation was collected at two sites, one coastal and one inland, that are separated by less than 35 km. The sites are sufficiently close that airmass sources during this storm were almost identical, but the inland site was exposed to terrestrial sources of warm INP while the coastal site was not. Warm INP were more numerous in precipitation at the inland site by an order of magnitude. Using FLEXPART dispersion modelling and radar-derived cloud vertical structure, we detected influence from terrestrial INP sources at the inland site, but did not find clear evidence of marine warm INP at either site. We episodically detected warm INP from long-range transported sources at both sites. By extending the FLEXPART modelling using a meteorological reanalysis, we demonstrate that long-range transported warm INP are observed only when the upper tropospheric jet provided transport to cloud tops. Using radar-derived hydrometeor classifications, we demonstrate that hydrometeors over the terrestrially-influenced inland site were more likely to be in the ice phase for cloud temperatures between 0 C and -10 C. We thus conclude that terrestrial and long-range transported aerosol were important sources of warm INP during this atmospheric river. Meteorological details such as transport mechanism and cloud strucutre were important in determining warm INP source strength and injection temperature, and ultimately the impact of wam INP on mixed phase cloud properties. NSF award AGS-145147, NSF award AGS-1632913, USACE award W912HZ-15-2-0019 Research Data Curation Program, UC San Diego, La Jolla, 92093-0175 (https://lib.ucsd.edu/rdcp) Martin, Andrew C.; Cornwell, Gavin; Beall, Charlotte M.; Cannon, Forest; Reilly, Sean; Schaap, Bas; Lucero, Dolan; Creamean, Jessie; Ralph, F. Martin; Mix, Hari T.; Prather, Kimberly A. (2019). Data from: Contrasting Local and Long-Range-Transported Warm Ice-Nucleating Particles During an Atmospheric River in Coastal California, USA. UC San Diego Library Digital Collections. https://doi.org/10.6075/J05X274R Martin, A. C., Cornwell, G., Beall, C. M., Cannon, F., Reilly, S., Schaap, B., Lucero, D., Creamean, J., Ralph, F. M., Mix, H. T., and Prather, K.: Contrasting local and long-range-transported warm ice-nucleating particles during an atmospheric river in coastal California, USA, Atmos. Chem. Phys., 19, 4193-4210, https://doi.org/10.5194/acp-19-4193-2019, 2019. This data set contains laboratory analyses, modeling, meteorological and radar analyses presented in the publication.
Automated ice spectrometer Rawinsonde FLEXPART Meteorological observations and analyses