Description: We propose to develop a pair of particle counters with Pulse Height Analysis (PHA) that will represent the first two channels in the design of a new Nucleation-Mode Aerosol Sizing Spectrometer with PHA (NMASS-PHA). With 5 logarithmically-spaced sizing channels in the NMASS; the PHA can fill in the gaps between the relatively coarse bins.

Benefits: The successful implementation of PHA to a single channel and successfully stitching together subsequent channels; would allow a 5-channel NMASS to retrieve size distributions from 3-64 nm in 14 bins at 1 Hz; compared to the current limitation of 4 bins. This allows for more accurate observations of particle growth as particles coalesce in the Upper Troposphere; Lower Stratosphere (UTLS) and better resolution of the sharp peaks associated with aircraft engine exhaust when characterizing emissions.