SBIR-STTR Award

In this SBIR project we will develop a new compact laser-spectroscopic instrument to measure humidity in the upper troposphere under conditions favoring the formation of persistent aircraft-induced contrails and contrail-cirrus clouds. Aircraft-induced contrail-cirrus clouds account for the major share of aviation’s climate impact by way of radiative forcing. It is therefore critical to try and minimize the occurrence of contrails and contrail cirrus to reduce the climate impact of the global aviation fleet. Our system will make active contrail-cirrus avoidance possible by the real-time measurement of the humidity state of the atmosphere and hence allow for active cirrus-contrail mitigation strategies. The system we propose will measure atmospheric humidity using laser spectroscopy and will provide a better detection limit than presently available commercial technology. It will have low-power consumption, and will be compact enough to be a permanent asset including data downlink on commercial aircraft for continuous humidity monitoring at cruise altitude as well as during the ascent/descent profiles. To minimize the climate impact of global aviation we need aircraft equipped with our technology that fly on intercontinental routes along the busiest flight corridors. Anticipated

Benefits:
Accurate humidity measurements are crucial for almost any scientific study of Earth’s atmosphere. A simple-to-integrate, highly compact, and maintenance free water vapor instrument for NASA aircraft campaigns would be a great asset for many scenarios. This includes satellite validation where a NASA aircraft would perform profile measurements co-located with satellite observations. Precise, compact, and low-power trace-gas sensors – not just for humidity – are relevant in many scientific and industrial applications, e.g. - Aircraft campaigns - remote field sites - industrial process control This project will be a key step in developing a new instrument platform for a wide range of applications in existing and new markets.

Our proposal provides a measurement technology to detect atmospheric conditions that favor the formation and persistence of aircraft-induced cirrus clouds in real time. These clouds account for the major share of aviation’s climate impact via radiative forcing. We need aircraft equipped with our technology that fly along the busiest flight corridors combined with adaptive flight routing as mitigation strategy. We are developing a new compact laser-spectroscopic instrument to measure the relevant humidity levels. During Phase I we achieved a relative uncertainty of 110 ppb (0.11 ppm) for real-time data recorded at 1 Hz with a short optical pathlength of only 30 cm. With further data averaging the relative uncertainty improved to ~25 ppb (0.025 ppm) for 1-minute averages. We have demonstrated excellent linearity of response of our Phase I benchtop system between 10 ppm and >6000 ppm. Based on simulated vertical profile measurements in the laboratory we estimate the accuracy of our Phase I benchtop system to be 1..2 ppm or ~2 %, whichever is greater. This performance makes our technology highly suitable for the proposed contrail avoidance application onboard aircraft. In Phase II we will further refine the instrument design with a strong focus on manufacturability and low cost. Innovations include an optical-fiber based open-path-free optical system with collimation optics and detector integrated into the sample cell, and a fast and efficient look-up based spectroscopic fit. We are actively planning the demonstration of the Phase II prototype instrument during an aircraft deployment. Anticipated

Benefits:
A simple-to-integrate, highly compact, and maintenance free water vapor instrument for NASA aircraft campaigns would be a great asset for many scenarios. This includes satellite validation where a NASA aircraft would perform profile measurements co-located with satellite observations. The project will enable commercial airspace management procedures that avoid contrail induced cirrus cloud, which has a significant short term climate benefit. Persistent contrail avoidance has emerged as a mitigation strategy for airlines to reduce their climate burden. The sensor enables a global system that quantifies the atmospheric state in real time, where contrails could be avoided with minor adjustments. The additional benefit of the technology developed here will involve assimilation of the water data by meteorological modeling systems.