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. 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. 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. The airborne PPS will be adapted from SPECs 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. 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 companys Learjet research aircraft. 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. 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. These in situ measurements can be used to validate spaceborne microphysical retrievals and provide data that can be parameterized to improve climate prediction models. Technical Objectives The overall technical objective is to develop and flight test a Particle Phase Spectrometer (PPS) that will discriminate water drops from ice particles as small as ~ 20 to 30 microns in mixed-phase clouds. Work Plan The airborne PPS will be adapted from SPEC’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 requires precision optics that were developed in Phase I. 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 fabricated and tested in the laboratory before being packaged into an airborne instrument and test-flown on the company’s Learjet research aircraft. Deliverables SPEC will deliver complete mechanical, optical and electrical specifications for the PPS, including all schematics, firmware and post-processing source code. The prototype PPS will be made available at no cost to NASA for the ARCSIX field program.
Benefits: The prototype PPS will be made available for installation on the NASA P-3B research aircraft that will participate in the NASA Arctic Radiation-Cloud-Aerosol-Surface-Interaction Experiment (ARCSIX) field campaign in the summer of 2024. It will also be available for additional NASA projects and can be installed on the NASA DC-8 and WB-57 research aircraft. Research aircraft continue to be a rich market for SPEC Inc., plus spin-off markets such as improved airborne measurements of ice and water content required for certification of commercial aircraft in mixed-phase icing conditions; and identification of smoke from wildfires and other airborne pollutants that cause human health concerns.