10th International Aerosol Conference
September 2 - September 7, 2018
America's Center Convention Complex
St. Louis, Missouri, USA

Abstract View


Ice Nucleating Particle Properties Relevant to Aerosol Cloud Interactions in the Himalaya Region

Shweta Yadav, Rebecca Venezia, Ryan Paerl, MARKUS PETTERS, North Carolina State University

     Abstract Number: 535
     Working Group: Unraveling the Many Facets of Ice Nucleating Particles and Their Interactions with Clouds

Abstract
The foothills of the Himalaya mountains are often blanketed by a thick haze layer that originates from anthropogenic and natural sources. There is a dearth of data on ice nucleating particle (INP) concentrations within these airmasses, thus limiting modelling studies that try to assess the influence of INPs on ice cloud formation. Here we present new data on INPs measured from filter and precipitation samples collected in rural and urban locations of northern India, including the states of Jammu & Kashmir, and Himachal Pradesh. In addition, we characterize the INP properties of mineral dust samples obtained from the Thar Desert, which is located in the northwestern part of the Indian subcontinent. Ice nucleation activity was obtained using the cold-stage technique. For the ambient samples, fluorescent particle size and concentration were determined using multi-wavelength flow cytometry. Factors that influence INP concentrations are explored. Results show that rainwater-derived INP concentrations are similar to the lower bound of observations obtained over the North American continent. Strong signals from pollution or bioaerosol were not evident. Ice nucleation active site density of Thar Desert dust, normalized by the geometric surface area of the aerosol, was similar for mobility-selected sizes ranging from 200-600 nm. Furthermore, the Thar Desert dust is well described by parameterizations that were built from dust data collected elsewhere around the globe. These data suggest that local pollution is not a strong source of INPs over the northern Indian subcontinent. Furthermore, existing dust parameterizations can be applied to estimate INP concentration if information about suspended dust surface area is available.