POPSnet - A spatially dense aerosol instrument network

High concentrations of fine aerosols (100 - 2,500 nm in diameter) have an adverse effect on air quality, and human health. Sparsely distributed measurements of particle number and size impede our understanding of aerosol emissions, transport, and radiative effects. The Portable Optical Particle Spectrometer network (POPSnet) is a spatially dense, long-term ground-based network of instruments at 13 sites distributed across a 150 km x 150 km region of relatively homogenous terrain at the Department of Energy Aerosol Radiation Measurement (ARM) Southern Great Plains (SGP) facility in Oklahoma. The goal of POPSnet-SGP is to make ambient microphysical measurements of near-surface aerosols with high spatial and temporal resolution over multiple annual cycles in order to determine the statistical representativeness of a single surface measurement within a model grid cell and thereby quantify the representation error in global climate models.

POPS instruments, miniaturized 3D printed optical particle counters, have been successfully deployed on high altitude balloons, unmanned aerial vehicles (UAVs), and research aircraft. POPS reports average 1Hz measurements of aerosol number and size distribution from 130 - 2,500 nm (assuming a modal refractive index of 0.53), and also records single particle counts and sizes. At each POPSnet-SGP installation site, two POPS operate in parallel, along with a searchPM, which measures PM₁, PM_2.5, PM₁₀, temperature, relative humidity, and carbon monoxide. Data from POPSnet-SGP is transmitted over a cellular network for analysis, ingestion into models, and near real time display on the web. This presentation describes the deployment of the first POPSnet-SGP installations and the initial characterization of measurement uncertainty in POPS size distributions based on the theoretical assumption of a uniform particle refractive index, the instrument precision and drift, and measured differences between ambient and instrument enclosure temperature.