Compact Nephelometer for Atmospheric Research with UAV

Atmospheric particles directly influence the climate by affecting the earth’s radiative balance by scattering and absorbing radiation and facilitating cloud formation. Uncertainties in aerosol/cloud interactions and the associated radiative effects remain the dominant contributors to the overall uncertainty in climate forecasting. In-situ measurements are essential for relating aerosol optical properties to chemical emissions and for validating remote sensing retrieval, atmospheric models, and emission inventories. Small unmanned aerial vehicles are well-suited for atmospheric measurements in conditions that are logistically difficult for ground‐based measurements, too dangerous, or cost‐prohibitive for mannedaircraft. Despite the advantages of unmanned aerial vehicles, no instrumentation has been designed for precise measurements of aerosol properties in the restrictive environment that lightweight unmanned aerial vehicle platforms present. To address the need for innovative instrumentation suitable for use on unmanned aerial vehicles for measurement of aerosol and cloud properties, development of an innovative compact nephelometer is proposed. The nephelometer will be capable of simultaneous measurements of both aerosol extinction and scattering coefficients with a high data acquisition rate of 1 s and sensitivity of better than 1 Mm-1. The proposed design is based on the innovative modification of a ring-down cavity allowing for significant size and weight reduction, improvement of device rigidity, and enhancement of its sensitivity. Phase I will comprise the design, fabrication, assembly, and testing of the nephelometer prototype, including its calibration with a set of test aerosols with known size and refractive index. The benefits of using a nephelometer on an unmanned aerial vehicle platform will be demonstrated by determining its limits of detection and long-term stability. This device will be used for in-situ measurements of aerosol parameters from unmanned aerial vehicles. Uncertainty regarding aerosol properties remains the major contributor to uncertainty in various models of future climate change. This instrument, on unmanned aerial vehicles, will significantly reduce research costs and enable more frequent flights. Commercial Applications and Other Benefits: The proposed device can be used both on aerial platforms and for ground-based observations. Besides climate research, the proposed device may be utilized to monitor air quality and quantify air pollutants from such unmanned platforms. With small modifications, it can be used for quantitative measurements concentrations of various gaseous components in the air, including NO2, CO2, CH4, and other greenhouse gases. It can also be adapted to tracing concentrations of volatile compounds and other substances affecting human health.