Performance Assessment of Portable Optical Particle Spectrometer (POPS)

Area of Science:

• Atmospheric Science
• Aerosol Science
• Instrumentation

Background:

• Accurate atmospheric aerosol property measurement is crucial for climate and air quality research.
• Miniaturized instrumentation is needed for deployment on small aerial platforms like unmanned aerial systems (UAS).
• The Portable Optical Particle Spectrometer (POPS) is designed for high-resolution aerosol size distribution measurements on small platforms.

Purpose of the Study:

• To evaluate the performance of an upgraded Portable Optical Particle Spectrometer (POPS).
• To assess the POPS's reliability under various environmental conditions and compare it with a reference instrument.

Main Methods:

• Performance evaluation of a POPS with enhanced temperature control (laser heater and pathway sensors).
• In situ measurements comparing POPS data with an Ultra-High Sensitivity Aerosol Spectrometer (UHSAS).
• Analysis of coincidence error and size distribution accuracy under varying aerosol concentrations.

Main Results:

• POPS maintains performance when laser temperature is >25°C and aerosol flow temperature is 15°C above ambient.
• Coincidence error for POPS is <25% at concentrations <4000 cm⁻³.
• Both POPS and UHSAS measure unaffected size distributions up to 15,000 cm⁻³, though POPS sizing is more sensitive to aerosol composition and morphology.

Conclusions:

• The upgraded POPS is a viable instrument for airborne aerosol measurements within defined operational parameters.
• Environmental conditions, particularly temperature, significantly influence POPS performance.
• Aerosol properties like composition and morphology impact sizing accuracy for both instruments, with a greater effect on POPS.