Meteorological -High Altitude Laser Optical Spectrometer (HALOS) for atmospheric water and temperature measurements

Airborne meteorological instruments are key to climate science, of which understanding cloud formation is an important component. Cloud formation involves the entrainment of air with dissimilar convective, thermal, and humidity properties. Improved understanding of these meteorological parameters can improve forecasting. The National Oceanic and Atmospheric Administration (NOAA) currently relies on outboard sensors with 25 Hz sampling, giving 10 m spatial resolution during nominal fixed wing aircraft flights. Higher-resolution humidity and temperature data are needed. We describe a novel laser absorption-based instrument that can make high sensitivity airborne measurements with 25 cm spatial resolution. The use of mid-infrared (MIR) quantum cascade lasers (QCLs) enables high sensitivity humidity measurements based on strong fundamental vibrations of water vapor. Sampling at 1 MHz (averaged data output exceeding 1 kHz) enables the high spatial resolution from a jet platform that accesses near the ground to 45,000 ft. This technology could be extended using complementary lasers to identify any Chemical, Biological, Radiological, and Nuclear (CBRN) threats, or hazardous material incidents, based on their MIR absorption features. Additional applications could also include highly accurate information for combating wildfires and high-speed identification of anomalous gas-phase species in semiconductor processing. © 2022 SPIE.

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