A Particle Phase Spectrometer for Cloud Microphysics Research

The 2021 IPCC report on the physical basis of climate change confirms that the Arctic is warming at nearly twice the rate of the global average. The 2021 IPCC report reconfirms previous IPCC reports since 2001 that clouds represent the largest uncertainty in climate models.nbsp; Arctic mixed-phase clouds have a major impact on surface radiative fluxes and energy balance, which are critical to understanding climate change. The objective of the proposed research is the development and flight-testing of a new airborne instrument, a Particle Phase Spectrometer (PPS), which will provide measurements of the ice and water phases in mixed-phase clouds.nbsp; These in situ measurements can be used to validate spaceborne microphysical retrievals and provide data that can be parameterized to improve climate prediction models. The PPS will discriminate small (~ 20 to 30 micron) water drops from ice particles in mixed-phase clouds.nbsp;The airborne PPS will be adapted from SPECrsquo;s commercial 3V-CPI, which combines a cloud particle imager (CPI) with 2.3 micron pixels and a 2D-S optical array probe with 10-micron resolution. The PPS will have 1-micron resolution and the 2D-S will be replaced with a 4-level 2D-Gray probe with 5-micron resolution. To achieve these goals requires substantial engineering and meticulous fabrication of components. The 1-micron resolution CPI is near the diffraction wavelength limit and requires precision optics that were developed in Phase I.nbsp; It also requires a high-power (200 W) pulsed laser with a 10 ns pulse length. The 5-micron 2D-Gray probe requires ultra-low noise amplification and FPGA (field programmable gate array) compression of large, high-rate data streams. The two airborne subsystems will be designed using solid modeling, fabricated and tested in the laboratory before being packaged into an airborne instrument and test-flown on the companyrsquo;s Learjet research aircraft.nbsp;